4122 строки
110 KiB
C
4122 строки
110 KiB
C
/*
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* linux/mm/memory.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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/*
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* demand-loading started 01.12.91 - seems it is high on the list of
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* things wanted, and it should be easy to implement. - Linus
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*/
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/*
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* Ok, demand-loading was easy, shared pages a little bit tricker. Shared
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* pages started 02.12.91, seems to work. - Linus.
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*
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* Tested sharing by executing about 30 /bin/sh: under the old kernel it
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* would have taken more than the 6M I have free, but it worked well as
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* far as I could see.
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*
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* Also corrected some "invalidate()"s - I wasn't doing enough of them.
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*/
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/*
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* Real VM (paging to/from disk) started 18.12.91. Much more work and
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* thought has to go into this. Oh, well..
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* 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
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* Found it. Everything seems to work now.
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* 20.12.91 - Ok, making the swap-device changeable like the root.
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*/
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/*
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* 05.04.94 - Multi-page memory management added for v1.1.
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* Idea by Alex Bligh (alex@cconcepts.co.uk)
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*
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* 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
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* (Gerhard.Wichert@pdb.siemens.de)
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*
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* Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
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*/
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#include <linux/kernel_stat.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <linux/mman.h>
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#include <linux/swap.h>
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#include <linux/highmem.h>
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#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
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#include <linux/export.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/pfn_t.h>
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#include <linux/writeback.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/kallsyms.h>
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#include <linux/swapops.h>
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#include <linux/elf.h>
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#include <linux/gfp.h>
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#include <linux/migrate.h>
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#include <linux/string.h>
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#include <linux/dma-debug.h>
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#include <linux/debugfs.h>
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#include <linux/userfaultfd_k.h>
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#include <linux/dax.h>
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#include <asm/io.h>
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#include <asm/mmu_context.h>
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#include <asm/pgalloc.h>
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#include <asm/uaccess.h>
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#include <asm/tlb.h>
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#include <asm/tlbflush.h>
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#include <asm/pgtable.h>
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#include "internal.h"
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#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
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#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
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#endif
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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
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unsigned long max_mapnr;
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struct page *mem_map;
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EXPORT_SYMBOL(max_mapnr);
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EXPORT_SYMBOL(mem_map);
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#endif
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/*
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* A number of key systems in x86 including ioremap() rely on the assumption
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* that high_memory defines the upper bound on direct map memory, then end
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* of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
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* highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
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* and ZONE_HIGHMEM.
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*/
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void * high_memory;
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EXPORT_SYMBOL(high_memory);
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/*
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* Randomize the address space (stacks, mmaps, brk, etc.).
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*
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* ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
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* as ancient (libc5 based) binaries can segfault. )
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*/
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int randomize_va_space __read_mostly =
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#ifdef CONFIG_COMPAT_BRK
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1;
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#else
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2;
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#endif
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static int __init disable_randmaps(char *s)
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{
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randomize_va_space = 0;
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return 1;
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}
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__setup("norandmaps", disable_randmaps);
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unsigned long zero_pfn __read_mostly;
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unsigned long highest_memmap_pfn __read_mostly;
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EXPORT_SYMBOL(zero_pfn);
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/*
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* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
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*/
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static int __init init_zero_pfn(void)
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{
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zero_pfn = page_to_pfn(ZERO_PAGE(0));
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return 0;
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}
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core_initcall(init_zero_pfn);
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#if defined(SPLIT_RSS_COUNTING)
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void sync_mm_rss(struct mm_struct *mm)
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{
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int i;
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for (i = 0; i < NR_MM_COUNTERS; i++) {
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if (current->rss_stat.count[i]) {
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add_mm_counter(mm, i, current->rss_stat.count[i]);
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current->rss_stat.count[i] = 0;
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}
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}
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current->rss_stat.events = 0;
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}
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static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
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{
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struct task_struct *task = current;
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if (likely(task->mm == mm))
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task->rss_stat.count[member] += val;
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else
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add_mm_counter(mm, member, val);
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}
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#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
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#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
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/* sync counter once per 64 page faults */
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#define TASK_RSS_EVENTS_THRESH (64)
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static void check_sync_rss_stat(struct task_struct *task)
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{
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if (unlikely(task != current))
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return;
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if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
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sync_mm_rss(task->mm);
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}
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#else /* SPLIT_RSS_COUNTING */
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#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
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#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
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static void check_sync_rss_stat(struct task_struct *task)
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{
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}
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#endif /* SPLIT_RSS_COUNTING */
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#ifdef HAVE_GENERIC_MMU_GATHER
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static bool tlb_next_batch(struct mmu_gather *tlb)
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{
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struct mmu_gather_batch *batch;
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batch = tlb->active;
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if (batch->next) {
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tlb->active = batch->next;
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return true;
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}
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if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
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return false;
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batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
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if (!batch)
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return false;
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tlb->batch_count++;
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batch->next = NULL;
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batch->nr = 0;
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batch->max = MAX_GATHER_BATCH;
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tlb->active->next = batch;
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tlb->active = batch;
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return true;
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}
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/* tlb_gather_mmu
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* Called to initialize an (on-stack) mmu_gather structure for page-table
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* tear-down from @mm. The @fullmm argument is used when @mm is without
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* users and we're going to destroy the full address space (exit/execve).
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*/
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void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
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{
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tlb->mm = mm;
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/* Is it from 0 to ~0? */
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tlb->fullmm = !(start | (end+1));
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tlb->need_flush_all = 0;
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tlb->local.next = NULL;
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tlb->local.nr = 0;
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tlb->local.max = ARRAY_SIZE(tlb->__pages);
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tlb->active = &tlb->local;
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tlb->batch_count = 0;
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
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tlb->batch = NULL;
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#endif
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tlb->page_size = 0;
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__tlb_reset_range(tlb);
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}
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static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
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{
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if (!tlb->end)
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return;
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tlb_flush(tlb);
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mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
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tlb_table_flush(tlb);
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#endif
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__tlb_reset_range(tlb);
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}
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static void tlb_flush_mmu_free(struct mmu_gather *tlb)
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{
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struct mmu_gather_batch *batch;
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for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
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free_pages_and_swap_cache(batch->pages, batch->nr);
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batch->nr = 0;
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}
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tlb->active = &tlb->local;
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}
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void tlb_flush_mmu(struct mmu_gather *tlb)
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{
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tlb_flush_mmu_tlbonly(tlb);
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tlb_flush_mmu_free(tlb);
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}
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/* tlb_finish_mmu
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* Called at the end of the shootdown operation to free up any resources
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* that were required.
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*/
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void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
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{
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struct mmu_gather_batch *batch, *next;
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tlb_flush_mmu(tlb);
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/* keep the page table cache within bounds */
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check_pgt_cache();
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for (batch = tlb->local.next; batch; batch = next) {
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next = batch->next;
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free_pages((unsigned long)batch, 0);
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}
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tlb->local.next = NULL;
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}
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/* __tlb_remove_page
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* Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
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* handling the additional races in SMP caused by other CPUs caching valid
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* mappings in their TLBs. Returns the number of free page slots left.
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* When out of page slots we must call tlb_flush_mmu().
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*returns true if the caller should flush.
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*/
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bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
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{
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struct mmu_gather_batch *batch;
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VM_BUG_ON(!tlb->end);
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if (!tlb->page_size)
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tlb->page_size = page_size;
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else {
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if (page_size != tlb->page_size)
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return true;
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}
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batch = tlb->active;
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if (batch->nr == batch->max) {
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if (!tlb_next_batch(tlb))
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return true;
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batch = tlb->active;
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}
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VM_BUG_ON_PAGE(batch->nr > batch->max, page);
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batch->pages[batch->nr++] = page;
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return false;
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}
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#endif /* HAVE_GENERIC_MMU_GATHER */
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#ifdef CONFIG_HAVE_RCU_TABLE_FREE
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/*
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* See the comment near struct mmu_table_batch.
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*/
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static void tlb_remove_table_smp_sync(void *arg)
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{
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/* Simply deliver the interrupt */
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}
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static void tlb_remove_table_one(void *table)
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{
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/*
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* This isn't an RCU grace period and hence the page-tables cannot be
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* assumed to be actually RCU-freed.
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*
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* It is however sufficient for software page-table walkers that rely on
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* IRQ disabling. See the comment near struct mmu_table_batch.
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*/
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smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
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__tlb_remove_table(table);
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}
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static void tlb_remove_table_rcu(struct rcu_head *head)
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{
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struct mmu_table_batch *batch;
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int i;
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batch = container_of(head, struct mmu_table_batch, rcu);
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for (i = 0; i < batch->nr; i++)
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__tlb_remove_table(batch->tables[i]);
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free_page((unsigned long)batch);
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}
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void tlb_table_flush(struct mmu_gather *tlb)
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{
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struct mmu_table_batch **batch = &tlb->batch;
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if (*batch) {
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call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
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*batch = NULL;
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}
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}
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void tlb_remove_table(struct mmu_gather *tlb, void *table)
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{
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struct mmu_table_batch **batch = &tlb->batch;
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/*
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* When there's less then two users of this mm there cannot be a
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* concurrent page-table walk.
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*/
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if (atomic_read(&tlb->mm->mm_users) < 2) {
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__tlb_remove_table(table);
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return;
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}
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if (*batch == NULL) {
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*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
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if (*batch == NULL) {
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tlb_remove_table_one(table);
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return;
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}
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(*batch)->nr = 0;
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}
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(*batch)->tables[(*batch)->nr++] = table;
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if ((*batch)->nr == MAX_TABLE_BATCH)
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tlb_table_flush(tlb);
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}
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#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
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/*
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* Note: this doesn't free the actual pages themselves. That
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* has been handled earlier when unmapping all the memory regions.
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*/
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static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
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unsigned long addr)
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{
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pgtable_t token = pmd_pgtable(*pmd);
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pmd_clear(pmd);
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pte_free_tlb(tlb, token, addr);
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atomic_long_dec(&tlb->mm->nr_ptes);
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}
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static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pmd_t *pmd;
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unsigned long next;
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unsigned long start;
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start = addr;
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pmd = pmd_offset(pud, addr);
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do {
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next = pmd_addr_end(addr, end);
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if (pmd_none_or_clear_bad(pmd))
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continue;
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free_pte_range(tlb, pmd, addr);
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} while (pmd++, addr = next, addr != end);
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start &= PUD_MASK;
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if (start < floor)
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return;
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if (ceiling) {
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ceiling &= PUD_MASK;
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if (!ceiling)
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return;
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}
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if (end - 1 > ceiling - 1)
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return;
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pmd = pmd_offset(pud, start);
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pud_clear(pud);
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pmd_free_tlb(tlb, pmd, start);
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mm_dec_nr_pmds(tlb->mm);
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}
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static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pud_t *pud;
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unsigned long next;
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unsigned long start;
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start = addr;
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pud = pud_offset(pgd, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud))
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continue;
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free_pmd_range(tlb, pud, addr, next, floor, ceiling);
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} while (pud++, addr = next, addr != end);
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start &= PGDIR_MASK;
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if (start < floor)
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return;
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if (ceiling) {
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ceiling &= PGDIR_MASK;
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if (!ceiling)
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return;
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}
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if (end - 1 > ceiling - 1)
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return;
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pud = pud_offset(pgd, start);
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pgd_clear(pgd);
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pud_free_tlb(tlb, pud, start);
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}
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/*
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* This function frees user-level page tables of a process.
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*/
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void free_pgd_range(struct mmu_gather *tlb,
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unsigned long addr, unsigned long end,
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unsigned long floor, unsigned long ceiling)
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{
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pgd_t *pgd;
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unsigned long next;
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/*
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* The next few lines have given us lots of grief...
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*
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* Why are we testing PMD* at this top level? Because often
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* there will be no work to do at all, and we'd prefer not to
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* go all the way down to the bottom just to discover that.
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*
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* Why all these "- 1"s? Because 0 represents both the bottom
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* of the address space and the top of it (using -1 for the
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* top wouldn't help much: the masks would do the wrong thing).
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* The rule is that addr 0 and floor 0 refer to the bottom of
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* the address space, but end 0 and ceiling 0 refer to the top
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* Comparisons need to use "end - 1" and "ceiling - 1" (though
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* that end 0 case should be mythical).
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*
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* Wherever addr is brought up or ceiling brought down, we must
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* be careful to reject "the opposite 0" before it confuses the
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* subsequent tests. But what about where end is brought down
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* by PMD_SIZE below? no, end can't go down to 0 there.
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*
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* Whereas we round start (addr) and ceiling down, by different
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* masks at different levels, in order to test whether a table
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* now has no other vmas using it, so can be freed, we don't
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* bother to round floor or end up - the tests don't need that.
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*/
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addr &= PMD_MASK;
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if (addr < floor) {
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addr += PMD_SIZE;
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if (!addr)
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return;
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|
}
|
|
if (ceiling) {
|
|
ceiling &= PMD_MASK;
|
|
if (!ceiling)
|
|
return;
|
|
}
|
|
if (end - 1 > ceiling - 1)
|
|
end -= PMD_SIZE;
|
|
if (addr > end - 1)
|
|
return;
|
|
|
|
pgd = pgd_offset(tlb->mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
continue;
|
|
free_pud_range(tlb, pgd, addr, next, floor, ceiling);
|
|
} while (pgd++, addr = next, addr != end);
|
|
}
|
|
|
|
void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
|
|
unsigned long floor, unsigned long ceiling)
|
|
{
|
|
while (vma) {
|
|
struct vm_area_struct *next = vma->vm_next;
|
|
unsigned long addr = vma->vm_start;
|
|
|
|
/*
|
|
* Hide vma from rmap and truncate_pagecache before freeing
|
|
* pgtables
|
|
*/
|
|
unlink_anon_vmas(vma);
|
|
unlink_file_vma(vma);
|
|
|
|
if (is_vm_hugetlb_page(vma)) {
|
|
hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
|
|
floor, next? next->vm_start: ceiling);
|
|
} else {
|
|
/*
|
|
* Optimization: gather nearby vmas into one call down
|
|
*/
|
|
while (next && next->vm_start <= vma->vm_end + PMD_SIZE
|
|
&& !is_vm_hugetlb_page(next)) {
|
|
vma = next;
|
|
next = vma->vm_next;
|
|
unlink_anon_vmas(vma);
|
|
unlink_file_vma(vma);
|
|
}
|
|
free_pgd_range(tlb, addr, vma->vm_end,
|
|
floor, next? next->vm_start: ceiling);
|
|
}
|
|
vma = next;
|
|
}
|
|
}
|
|
|
|
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
|
|
{
|
|
spinlock_t *ptl;
|
|
pgtable_t new = pte_alloc_one(mm, address);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
/*
|
|
* Ensure all pte setup (eg. pte page lock and page clearing) are
|
|
* visible before the pte is made visible to other CPUs by being
|
|
* put into page tables.
|
|
*
|
|
* The other side of the story is the pointer chasing in the page
|
|
* table walking code (when walking the page table without locking;
|
|
* ie. most of the time). Fortunately, these data accesses consist
|
|
* of a chain of data-dependent loads, meaning most CPUs (alpha
|
|
* being the notable exception) will already guarantee loads are
|
|
* seen in-order. See the alpha page table accessors for the
|
|
* smp_read_barrier_depends() barriers in page table walking code.
|
|
*/
|
|
smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
|
|
|
|
ptl = pmd_lock(mm, pmd);
|
|
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
|
|
atomic_long_inc(&mm->nr_ptes);
|
|
pmd_populate(mm, pmd, new);
|
|
new = NULL;
|
|
}
|
|
spin_unlock(ptl);
|
|
if (new)
|
|
pte_free(mm, new);
|
|
return 0;
|
|
}
|
|
|
|
int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
|
|
{
|
|
pte_t *new = pte_alloc_one_kernel(&init_mm, address);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
smp_wmb(); /* See comment in __pte_alloc */
|
|
|
|
spin_lock(&init_mm.page_table_lock);
|
|
if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
|
|
pmd_populate_kernel(&init_mm, pmd, new);
|
|
new = NULL;
|
|
}
|
|
spin_unlock(&init_mm.page_table_lock);
|
|
if (new)
|
|
pte_free_kernel(&init_mm, new);
|
|
return 0;
|
|
}
|
|
|
|
static inline void init_rss_vec(int *rss)
|
|
{
|
|
memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
|
|
}
|
|
|
|
static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
|
|
{
|
|
int i;
|
|
|
|
if (current->mm == mm)
|
|
sync_mm_rss(mm);
|
|
for (i = 0; i < NR_MM_COUNTERS; i++)
|
|
if (rss[i])
|
|
add_mm_counter(mm, i, rss[i]);
|
|
}
|
|
|
|
/*
|
|
* This function is called to print an error when a bad pte
|
|
* is found. For example, we might have a PFN-mapped pte in
|
|
* a region that doesn't allow it.
|
|
*
|
|
* The calling function must still handle the error.
|
|
*/
|
|
static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
|
|
pte_t pte, struct page *page)
|
|
{
|
|
pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
|
|
pud_t *pud = pud_offset(pgd, addr);
|
|
pmd_t *pmd = pmd_offset(pud, addr);
|
|
struct address_space *mapping;
|
|
pgoff_t index;
|
|
static unsigned long resume;
|
|
static unsigned long nr_shown;
|
|
static unsigned long nr_unshown;
|
|
|
|
/*
|
|
* Allow a burst of 60 reports, then keep quiet for that minute;
|
|
* or allow a steady drip of one report per second.
|
|
*/
|
|
if (nr_shown == 60) {
|
|
if (time_before(jiffies, resume)) {
|
|
nr_unshown++;
|
|
return;
|
|
}
|
|
if (nr_unshown) {
|
|
pr_alert("BUG: Bad page map: %lu messages suppressed\n",
|
|
nr_unshown);
|
|
nr_unshown = 0;
|
|
}
|
|
nr_shown = 0;
|
|
}
|
|
if (nr_shown++ == 0)
|
|
resume = jiffies + 60 * HZ;
|
|
|
|
mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
|
|
index = linear_page_index(vma, addr);
|
|
|
|
pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
|
|
current->comm,
|
|
(long long)pte_val(pte), (long long)pmd_val(*pmd));
|
|
if (page)
|
|
dump_page(page, "bad pte");
|
|
pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
|
|
(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
|
|
/*
|
|
* Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
|
|
*/
|
|
pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
|
|
vma->vm_file,
|
|
vma->vm_ops ? vma->vm_ops->fault : NULL,
|
|
vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
|
|
mapping ? mapping->a_ops->readpage : NULL);
|
|
dump_stack();
|
|
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
|
|
}
|
|
|
|
/*
|
|
* vm_normal_page -- This function gets the "struct page" associated with a pte.
|
|
*
|
|
* "Special" mappings do not wish to be associated with a "struct page" (either
|
|
* it doesn't exist, or it exists but they don't want to touch it). In this
|
|
* case, NULL is returned here. "Normal" mappings do have a struct page.
|
|
*
|
|
* There are 2 broad cases. Firstly, an architecture may define a pte_special()
|
|
* pte bit, in which case this function is trivial. Secondly, an architecture
|
|
* may not have a spare pte bit, which requires a more complicated scheme,
|
|
* described below.
|
|
*
|
|
* A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
|
|
* special mapping (even if there are underlying and valid "struct pages").
|
|
* COWed pages of a VM_PFNMAP are always normal.
|
|
*
|
|
* The way we recognize COWed pages within VM_PFNMAP mappings is through the
|
|
* rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
|
|
* set, and the vm_pgoff will point to the first PFN mapped: thus every special
|
|
* mapping will always honor the rule
|
|
*
|
|
* pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
|
|
*
|
|
* And for normal mappings this is false.
|
|
*
|
|
* This restricts such mappings to be a linear translation from virtual address
|
|
* to pfn. To get around this restriction, we allow arbitrary mappings so long
|
|
* as the vma is not a COW mapping; in that case, we know that all ptes are
|
|
* special (because none can have been COWed).
|
|
*
|
|
*
|
|
* In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
|
|
*
|
|
* VM_MIXEDMAP mappings can likewise contain memory with or without "struct
|
|
* page" backing, however the difference is that _all_ pages with a struct
|
|
* page (that is, those where pfn_valid is true) are refcounted and considered
|
|
* normal pages by the VM. The disadvantage is that pages are refcounted
|
|
* (which can be slower and simply not an option for some PFNMAP users). The
|
|
* advantage is that we don't have to follow the strict linearity rule of
|
|
* PFNMAP mappings in order to support COWable mappings.
|
|
*
|
|
*/
|
|
#ifdef __HAVE_ARCH_PTE_SPECIAL
|
|
# define HAVE_PTE_SPECIAL 1
|
|
#else
|
|
# define HAVE_PTE_SPECIAL 0
|
|
#endif
|
|
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
|
|
pte_t pte)
|
|
{
|
|
unsigned long pfn = pte_pfn(pte);
|
|
|
|
if (HAVE_PTE_SPECIAL) {
|
|
if (likely(!pte_special(pte)))
|
|
goto check_pfn;
|
|
if (vma->vm_ops && vma->vm_ops->find_special_page)
|
|
return vma->vm_ops->find_special_page(vma, addr);
|
|
if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
|
|
return NULL;
|
|
if (!is_zero_pfn(pfn))
|
|
print_bad_pte(vma, addr, pte, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
/* !HAVE_PTE_SPECIAL case follows: */
|
|
|
|
if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
|
|
if (vma->vm_flags & VM_MIXEDMAP) {
|
|
if (!pfn_valid(pfn))
|
|
return NULL;
|
|
goto out;
|
|
} else {
|
|
unsigned long off;
|
|
off = (addr - vma->vm_start) >> PAGE_SHIFT;
|
|
if (pfn == vma->vm_pgoff + off)
|
|
return NULL;
|
|
if (!is_cow_mapping(vma->vm_flags))
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
if (is_zero_pfn(pfn))
|
|
return NULL;
|
|
check_pfn:
|
|
if (unlikely(pfn > highest_memmap_pfn)) {
|
|
print_bad_pte(vma, addr, pte, NULL);
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* NOTE! We still have PageReserved() pages in the page tables.
|
|
* eg. VDSO mappings can cause them to exist.
|
|
*/
|
|
out:
|
|
return pfn_to_page(pfn);
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
|
|
pmd_t pmd)
|
|
{
|
|
unsigned long pfn = pmd_pfn(pmd);
|
|
|
|
/*
|
|
* There is no pmd_special() but there may be special pmds, e.g.
|
|
* in a direct-access (dax) mapping, so let's just replicate the
|
|
* !HAVE_PTE_SPECIAL case from vm_normal_page() here.
|
|
*/
|
|
if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
|
|
if (vma->vm_flags & VM_MIXEDMAP) {
|
|
if (!pfn_valid(pfn))
|
|
return NULL;
|
|
goto out;
|
|
} else {
|
|
unsigned long off;
|
|
off = (addr - vma->vm_start) >> PAGE_SHIFT;
|
|
if (pfn == vma->vm_pgoff + off)
|
|
return NULL;
|
|
if (!is_cow_mapping(vma->vm_flags))
|
|
return NULL;
|
|
}
|
|
}
|
|
|
|
if (is_zero_pfn(pfn))
|
|
return NULL;
|
|
if (unlikely(pfn > highest_memmap_pfn))
|
|
return NULL;
|
|
|
|
/*
|
|
* NOTE! We still have PageReserved() pages in the page tables.
|
|
* eg. VDSO mappings can cause them to exist.
|
|
*/
|
|
out:
|
|
return pfn_to_page(pfn);
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* copy one vm_area from one task to the other. Assumes the page tables
|
|
* already present in the new task to be cleared in the whole range
|
|
* covered by this vma.
|
|
*/
|
|
|
|
static inline unsigned long
|
|
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
|
|
unsigned long addr, int *rss)
|
|
{
|
|
unsigned long vm_flags = vma->vm_flags;
|
|
pte_t pte = *src_pte;
|
|
struct page *page;
|
|
|
|
/* pte contains position in swap or file, so copy. */
|
|
if (unlikely(!pte_present(pte))) {
|
|
swp_entry_t entry = pte_to_swp_entry(pte);
|
|
|
|
if (likely(!non_swap_entry(entry))) {
|
|
if (swap_duplicate(entry) < 0)
|
|
return entry.val;
|
|
|
|
/* make sure dst_mm is on swapoff's mmlist. */
|
|
if (unlikely(list_empty(&dst_mm->mmlist))) {
|
|
spin_lock(&mmlist_lock);
|
|
if (list_empty(&dst_mm->mmlist))
|
|
list_add(&dst_mm->mmlist,
|
|
&src_mm->mmlist);
|
|
spin_unlock(&mmlist_lock);
|
|
}
|
|
rss[MM_SWAPENTS]++;
|
|
} else if (is_migration_entry(entry)) {
|
|
page = migration_entry_to_page(entry);
|
|
|
|
rss[mm_counter(page)]++;
|
|
|
|
if (is_write_migration_entry(entry) &&
|
|
is_cow_mapping(vm_flags)) {
|
|
/*
|
|
* COW mappings require pages in both
|
|
* parent and child to be set to read.
|
|
*/
|
|
make_migration_entry_read(&entry);
|
|
pte = swp_entry_to_pte(entry);
|
|
if (pte_swp_soft_dirty(*src_pte))
|
|
pte = pte_swp_mksoft_dirty(pte);
|
|
set_pte_at(src_mm, addr, src_pte, pte);
|
|
}
|
|
}
|
|
goto out_set_pte;
|
|
}
|
|
|
|
/*
|
|
* If it's a COW mapping, write protect it both
|
|
* in the parent and the child
|
|
*/
|
|
if (is_cow_mapping(vm_flags)) {
|
|
ptep_set_wrprotect(src_mm, addr, src_pte);
|
|
pte = pte_wrprotect(pte);
|
|
}
|
|
|
|
/*
|
|
* If it's a shared mapping, mark it clean in
|
|
* the child
|
|
*/
|
|
if (vm_flags & VM_SHARED)
|
|
pte = pte_mkclean(pte);
|
|
pte = pte_mkold(pte);
|
|
|
|
page = vm_normal_page(vma, addr, pte);
|
|
if (page) {
|
|
get_page(page);
|
|
page_dup_rmap(page, false);
|
|
rss[mm_counter(page)]++;
|
|
}
|
|
|
|
out_set_pte:
|
|
set_pte_at(dst_mm, addr, dst_pte, pte);
|
|
return 0;
|
|
}
|
|
|
|
static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pte_t *orig_src_pte, *orig_dst_pte;
|
|
pte_t *src_pte, *dst_pte;
|
|
spinlock_t *src_ptl, *dst_ptl;
|
|
int progress = 0;
|
|
int rss[NR_MM_COUNTERS];
|
|
swp_entry_t entry = (swp_entry_t){0};
|
|
|
|
again:
|
|
init_rss_vec(rss);
|
|
|
|
dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
|
|
if (!dst_pte)
|
|
return -ENOMEM;
|
|
src_pte = pte_offset_map(src_pmd, addr);
|
|
src_ptl = pte_lockptr(src_mm, src_pmd);
|
|
spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
|
|
orig_src_pte = src_pte;
|
|
orig_dst_pte = dst_pte;
|
|
arch_enter_lazy_mmu_mode();
|
|
|
|
do {
|
|
/*
|
|
* We are holding two locks at this point - either of them
|
|
* could generate latencies in another task on another CPU.
|
|
*/
|
|
if (progress >= 32) {
|
|
progress = 0;
|
|
if (need_resched() ||
|
|
spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
|
|
break;
|
|
}
|
|
if (pte_none(*src_pte)) {
|
|
progress++;
|
|
continue;
|
|
}
|
|
entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
|
|
vma, addr, rss);
|
|
if (entry.val)
|
|
break;
|
|
progress += 8;
|
|
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
|
|
|
|
arch_leave_lazy_mmu_mode();
|
|
spin_unlock(src_ptl);
|
|
pte_unmap(orig_src_pte);
|
|
add_mm_rss_vec(dst_mm, rss);
|
|
pte_unmap_unlock(orig_dst_pte, dst_ptl);
|
|
cond_resched();
|
|
|
|
if (entry.val) {
|
|
if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
|
|
return -ENOMEM;
|
|
progress = 0;
|
|
}
|
|
if (addr != end)
|
|
goto again;
|
|
return 0;
|
|
}
|
|
|
|
static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pmd_t *src_pmd, *dst_pmd;
|
|
unsigned long next;
|
|
|
|
dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
|
|
if (!dst_pmd)
|
|
return -ENOMEM;
|
|
src_pmd = pmd_offset(src_pud, addr);
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
|
|
int err;
|
|
VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
|
|
err = copy_huge_pmd(dst_mm, src_mm,
|
|
dst_pmd, src_pmd, addr, vma);
|
|
if (err == -ENOMEM)
|
|
return -ENOMEM;
|
|
if (!err)
|
|
continue;
|
|
/* fall through */
|
|
}
|
|
if (pmd_none_or_clear_bad(src_pmd))
|
|
continue;
|
|
if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
|
|
vma, addr, next))
|
|
return -ENOMEM;
|
|
} while (dst_pmd++, src_pmd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end)
|
|
{
|
|
pud_t *src_pud, *dst_pud;
|
|
unsigned long next;
|
|
|
|
dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
|
|
if (!dst_pud)
|
|
return -ENOMEM;
|
|
src_pud = pud_offset(src_pgd, addr);
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
if (pud_none_or_clear_bad(src_pud))
|
|
continue;
|
|
if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
|
|
vma, addr, next))
|
|
return -ENOMEM;
|
|
} while (dst_pud++, src_pud++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
pgd_t *src_pgd, *dst_pgd;
|
|
unsigned long next;
|
|
unsigned long addr = vma->vm_start;
|
|
unsigned long end = vma->vm_end;
|
|
unsigned long mmun_start; /* For mmu_notifiers */
|
|
unsigned long mmun_end; /* For mmu_notifiers */
|
|
bool is_cow;
|
|
int ret;
|
|
|
|
/*
|
|
* Don't copy ptes where a page fault will fill them correctly.
|
|
* Fork becomes much lighter when there are big shared or private
|
|
* readonly mappings. The tradeoff is that copy_page_range is more
|
|
* efficient than faulting.
|
|
*/
|
|
if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
|
|
!vma->anon_vma)
|
|
return 0;
|
|
|
|
if (is_vm_hugetlb_page(vma))
|
|
return copy_hugetlb_page_range(dst_mm, src_mm, vma);
|
|
|
|
if (unlikely(vma->vm_flags & VM_PFNMAP)) {
|
|
/*
|
|
* We do not free on error cases below as remove_vma
|
|
* gets called on error from higher level routine
|
|
*/
|
|
ret = track_pfn_copy(vma);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* We need to invalidate the secondary MMU mappings only when
|
|
* there could be a permission downgrade on the ptes of the
|
|
* parent mm. And a permission downgrade will only happen if
|
|
* is_cow_mapping() returns true.
|
|
*/
|
|
is_cow = is_cow_mapping(vma->vm_flags);
|
|
mmun_start = addr;
|
|
mmun_end = end;
|
|
if (is_cow)
|
|
mmu_notifier_invalidate_range_start(src_mm, mmun_start,
|
|
mmun_end);
|
|
|
|
ret = 0;
|
|
dst_pgd = pgd_offset(dst_mm, addr);
|
|
src_pgd = pgd_offset(src_mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(src_pgd))
|
|
continue;
|
|
if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
|
|
vma, addr, next))) {
|
|
ret = -ENOMEM;
|
|
break;
|
|
}
|
|
} while (dst_pgd++, src_pgd++, addr = next, addr != end);
|
|
|
|
if (is_cow)
|
|
mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
|
|
return ret;
|
|
}
|
|
|
|
static unsigned long zap_pte_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end,
|
|
struct zap_details *details)
|
|
{
|
|
struct mm_struct *mm = tlb->mm;
|
|
int force_flush = 0;
|
|
int rss[NR_MM_COUNTERS];
|
|
spinlock_t *ptl;
|
|
pte_t *start_pte;
|
|
pte_t *pte;
|
|
swp_entry_t entry;
|
|
struct page *pending_page = NULL;
|
|
|
|
again:
|
|
init_rss_vec(rss);
|
|
start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
|
|
pte = start_pte;
|
|
arch_enter_lazy_mmu_mode();
|
|
do {
|
|
pte_t ptent = *pte;
|
|
if (pte_none(ptent)) {
|
|
continue;
|
|
}
|
|
|
|
if (pte_present(ptent)) {
|
|
struct page *page;
|
|
|
|
page = vm_normal_page(vma, addr, ptent);
|
|
if (unlikely(details) && page) {
|
|
/*
|
|
* unmap_shared_mapping_pages() wants to
|
|
* invalidate cache without truncating:
|
|
* unmap shared but keep private pages.
|
|
*/
|
|
if (details->check_mapping &&
|
|
details->check_mapping != page_rmapping(page))
|
|
continue;
|
|
}
|
|
ptent = ptep_get_and_clear_full(mm, addr, pte,
|
|
tlb->fullmm);
|
|
tlb_remove_tlb_entry(tlb, pte, addr);
|
|
if (unlikely(!page))
|
|
continue;
|
|
|
|
if (!PageAnon(page)) {
|
|
if (pte_dirty(ptent)) {
|
|
/*
|
|
* oom_reaper cannot tear down dirty
|
|
* pages
|
|
*/
|
|
if (unlikely(details && details->ignore_dirty))
|
|
continue;
|
|
force_flush = 1;
|
|
set_page_dirty(page);
|
|
}
|
|
if (pte_young(ptent) &&
|
|
likely(!(vma->vm_flags & VM_SEQ_READ)))
|
|
mark_page_accessed(page);
|
|
}
|
|
rss[mm_counter(page)]--;
|
|
page_remove_rmap(page, false);
|
|
if (unlikely(page_mapcount(page) < 0))
|
|
print_bad_pte(vma, addr, ptent, page);
|
|
if (unlikely(__tlb_remove_page(tlb, page))) {
|
|
force_flush = 1;
|
|
pending_page = page;
|
|
addr += PAGE_SIZE;
|
|
break;
|
|
}
|
|
continue;
|
|
}
|
|
/* only check swap_entries if explicitly asked for in details */
|
|
if (unlikely(details && !details->check_swap_entries))
|
|
continue;
|
|
|
|
entry = pte_to_swp_entry(ptent);
|
|
if (!non_swap_entry(entry))
|
|
rss[MM_SWAPENTS]--;
|
|
else if (is_migration_entry(entry)) {
|
|
struct page *page;
|
|
|
|
page = migration_entry_to_page(entry);
|
|
rss[mm_counter(page)]--;
|
|
}
|
|
if (unlikely(!free_swap_and_cache(entry)))
|
|
print_bad_pte(vma, addr, ptent, NULL);
|
|
pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
|
|
} while (pte++, addr += PAGE_SIZE, addr != end);
|
|
|
|
add_mm_rss_vec(mm, rss);
|
|
arch_leave_lazy_mmu_mode();
|
|
|
|
/* Do the actual TLB flush before dropping ptl */
|
|
if (force_flush)
|
|
tlb_flush_mmu_tlbonly(tlb);
|
|
pte_unmap_unlock(start_pte, ptl);
|
|
|
|
/*
|
|
* If we forced a TLB flush (either due to running out of
|
|
* batch buffers or because we needed to flush dirty TLB
|
|
* entries before releasing the ptl), free the batched
|
|
* memory too. Restart if we didn't do everything.
|
|
*/
|
|
if (force_flush) {
|
|
force_flush = 0;
|
|
tlb_flush_mmu_free(tlb);
|
|
if (pending_page) {
|
|
/* remove the page with new size */
|
|
__tlb_remove_pte_page(tlb, pending_page);
|
|
pending_page = NULL;
|
|
}
|
|
if (addr != end)
|
|
goto again;
|
|
}
|
|
|
|
return addr;
|
|
}
|
|
|
|
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, pud_t *pud,
|
|
unsigned long addr, unsigned long end,
|
|
struct zap_details *details)
|
|
{
|
|
pmd_t *pmd;
|
|
unsigned long next;
|
|
|
|
pmd = pmd_offset(pud, addr);
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
|
|
if (next - addr != HPAGE_PMD_SIZE) {
|
|
VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
|
|
!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
|
|
split_huge_pmd(vma, pmd, addr);
|
|
} else if (zap_huge_pmd(tlb, vma, pmd, addr))
|
|
goto next;
|
|
/* fall through */
|
|
}
|
|
/*
|
|
* Here there can be other concurrent MADV_DONTNEED or
|
|
* trans huge page faults running, and if the pmd is
|
|
* none or trans huge it can change under us. This is
|
|
* because MADV_DONTNEED holds the mmap_sem in read
|
|
* mode.
|
|
*/
|
|
if (pmd_none_or_trans_huge_or_clear_bad(pmd))
|
|
goto next;
|
|
next = zap_pte_range(tlb, vma, pmd, addr, next, details);
|
|
next:
|
|
cond_resched();
|
|
} while (pmd++, addr = next, addr != end);
|
|
|
|
return addr;
|
|
}
|
|
|
|
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, pgd_t *pgd,
|
|
unsigned long addr, unsigned long end,
|
|
struct zap_details *details)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
|
|
pud = pud_offset(pgd, addr);
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
if (pud_none_or_clear_bad(pud))
|
|
continue;
|
|
next = zap_pmd_range(tlb, vma, pud, addr, next, details);
|
|
} while (pud++, addr = next, addr != end);
|
|
|
|
return addr;
|
|
}
|
|
|
|
void unmap_page_range(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma,
|
|
unsigned long addr, unsigned long end,
|
|
struct zap_details *details)
|
|
{
|
|
pgd_t *pgd;
|
|
unsigned long next;
|
|
|
|
BUG_ON(addr >= end);
|
|
tlb_start_vma(tlb, vma);
|
|
pgd = pgd_offset(vma->vm_mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
if (pgd_none_or_clear_bad(pgd))
|
|
continue;
|
|
next = zap_pud_range(tlb, vma, pgd, addr, next, details);
|
|
} while (pgd++, addr = next, addr != end);
|
|
tlb_end_vma(tlb, vma);
|
|
}
|
|
|
|
|
|
static void unmap_single_vma(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, unsigned long start_addr,
|
|
unsigned long end_addr,
|
|
struct zap_details *details)
|
|
{
|
|
unsigned long start = max(vma->vm_start, start_addr);
|
|
unsigned long end;
|
|
|
|
if (start >= vma->vm_end)
|
|
return;
|
|
end = min(vma->vm_end, end_addr);
|
|
if (end <= vma->vm_start)
|
|
return;
|
|
|
|
if (vma->vm_file)
|
|
uprobe_munmap(vma, start, end);
|
|
|
|
if (unlikely(vma->vm_flags & VM_PFNMAP))
|
|
untrack_pfn(vma, 0, 0);
|
|
|
|
if (start != end) {
|
|
if (unlikely(is_vm_hugetlb_page(vma))) {
|
|
/*
|
|
* It is undesirable to test vma->vm_file as it
|
|
* should be non-null for valid hugetlb area.
|
|
* However, vm_file will be NULL in the error
|
|
* cleanup path of mmap_region. When
|
|
* hugetlbfs ->mmap method fails,
|
|
* mmap_region() nullifies vma->vm_file
|
|
* before calling this function to clean up.
|
|
* Since no pte has actually been setup, it is
|
|
* safe to do nothing in this case.
|
|
*/
|
|
if (vma->vm_file) {
|
|
i_mmap_lock_write(vma->vm_file->f_mapping);
|
|
__unmap_hugepage_range_final(tlb, vma, start, end, NULL);
|
|
i_mmap_unlock_write(vma->vm_file->f_mapping);
|
|
}
|
|
} else
|
|
unmap_page_range(tlb, vma, start, end, details);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* unmap_vmas - unmap a range of memory covered by a list of vma's
|
|
* @tlb: address of the caller's struct mmu_gather
|
|
* @vma: the starting vma
|
|
* @start_addr: virtual address at which to start unmapping
|
|
* @end_addr: virtual address at which to end unmapping
|
|
*
|
|
* Unmap all pages in the vma list.
|
|
*
|
|
* Only addresses between `start' and `end' will be unmapped.
|
|
*
|
|
* The VMA list must be sorted in ascending virtual address order.
|
|
*
|
|
* unmap_vmas() assumes that the caller will flush the whole unmapped address
|
|
* range after unmap_vmas() returns. So the only responsibility here is to
|
|
* ensure that any thus-far unmapped pages are flushed before unmap_vmas()
|
|
* drops the lock and schedules.
|
|
*/
|
|
void unmap_vmas(struct mmu_gather *tlb,
|
|
struct vm_area_struct *vma, unsigned long start_addr,
|
|
unsigned long end_addr)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
|
mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
|
|
for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
|
|
unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
|
|
mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
|
|
}
|
|
|
|
/**
|
|
* zap_page_range - remove user pages in a given range
|
|
* @vma: vm_area_struct holding the applicable pages
|
|
* @start: starting address of pages to zap
|
|
* @size: number of bytes to zap
|
|
* @details: details of shared cache invalidation
|
|
*
|
|
* Caller must protect the VMA list
|
|
*/
|
|
void zap_page_range(struct vm_area_struct *vma, unsigned long start,
|
|
unsigned long size, struct zap_details *details)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct mmu_gather tlb;
|
|
unsigned long end = start + size;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm, start, end);
|
|
update_hiwater_rss(mm);
|
|
mmu_notifier_invalidate_range_start(mm, start, end);
|
|
for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
|
|
unmap_single_vma(&tlb, vma, start, end, details);
|
|
mmu_notifier_invalidate_range_end(mm, start, end);
|
|
tlb_finish_mmu(&tlb, start, end);
|
|
}
|
|
|
|
/**
|
|
* zap_page_range_single - remove user pages in a given range
|
|
* @vma: vm_area_struct holding the applicable pages
|
|
* @address: starting address of pages to zap
|
|
* @size: number of bytes to zap
|
|
* @details: details of shared cache invalidation
|
|
*
|
|
* The range must fit into one VMA.
|
|
*/
|
|
static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned long size, struct zap_details *details)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct mmu_gather tlb;
|
|
unsigned long end = address + size;
|
|
|
|
lru_add_drain();
|
|
tlb_gather_mmu(&tlb, mm, address, end);
|
|
update_hiwater_rss(mm);
|
|
mmu_notifier_invalidate_range_start(mm, address, end);
|
|
unmap_single_vma(&tlb, vma, address, end, details);
|
|
mmu_notifier_invalidate_range_end(mm, address, end);
|
|
tlb_finish_mmu(&tlb, address, end);
|
|
}
|
|
|
|
/**
|
|
* zap_vma_ptes - remove ptes mapping the vma
|
|
* @vma: vm_area_struct holding ptes to be zapped
|
|
* @address: starting address of pages to zap
|
|
* @size: number of bytes to zap
|
|
*
|
|
* This function only unmaps ptes assigned to VM_PFNMAP vmas.
|
|
*
|
|
* The entire address range must be fully contained within the vma.
|
|
*
|
|
* Returns 0 if successful.
|
|
*/
|
|
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned long size)
|
|
{
|
|
if (address < vma->vm_start || address + size > vma->vm_end ||
|
|
!(vma->vm_flags & VM_PFNMAP))
|
|
return -1;
|
|
zap_page_range_single(vma, address, size, NULL);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(zap_vma_ptes);
|
|
|
|
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
|
|
spinlock_t **ptl)
|
|
{
|
|
pgd_t * pgd = pgd_offset(mm, addr);
|
|
pud_t * pud = pud_alloc(mm, pgd, addr);
|
|
if (pud) {
|
|
pmd_t * pmd = pmd_alloc(mm, pud, addr);
|
|
if (pmd) {
|
|
VM_BUG_ON(pmd_trans_huge(*pmd));
|
|
return pte_alloc_map_lock(mm, pmd, addr, ptl);
|
|
}
|
|
}
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* This is the old fallback for page remapping.
|
|
*
|
|
* For historical reasons, it only allows reserved pages. Only
|
|
* old drivers should use this, and they needed to mark their
|
|
* pages reserved for the old functions anyway.
|
|
*/
|
|
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
|
|
struct page *page, pgprot_t prot)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
int retval;
|
|
pte_t *pte;
|
|
spinlock_t *ptl;
|
|
|
|
retval = -EINVAL;
|
|
if (PageAnon(page))
|
|
goto out;
|
|
retval = -ENOMEM;
|
|
flush_dcache_page(page);
|
|
pte = get_locked_pte(mm, addr, &ptl);
|
|
if (!pte)
|
|
goto out;
|
|
retval = -EBUSY;
|
|
if (!pte_none(*pte))
|
|
goto out_unlock;
|
|
|
|
/* Ok, finally just insert the thing.. */
|
|
get_page(page);
|
|
inc_mm_counter_fast(mm, mm_counter_file(page));
|
|
page_add_file_rmap(page, false);
|
|
set_pte_at(mm, addr, pte, mk_pte(page, prot));
|
|
|
|
retval = 0;
|
|
pte_unmap_unlock(pte, ptl);
|
|
return retval;
|
|
out_unlock:
|
|
pte_unmap_unlock(pte, ptl);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* vm_insert_page - insert single page into user vma
|
|
* @vma: user vma to map to
|
|
* @addr: target user address of this page
|
|
* @page: source kernel page
|
|
*
|
|
* This allows drivers to insert individual pages they've allocated
|
|
* into a user vma.
|
|
*
|
|
* The page has to be a nice clean _individual_ kernel allocation.
|
|
* If you allocate a compound page, you need to have marked it as
|
|
* such (__GFP_COMP), or manually just split the page up yourself
|
|
* (see split_page()).
|
|
*
|
|
* NOTE! Traditionally this was done with "remap_pfn_range()" which
|
|
* took an arbitrary page protection parameter. This doesn't allow
|
|
* that. Your vma protection will have to be set up correctly, which
|
|
* means that if you want a shared writable mapping, you'd better
|
|
* ask for a shared writable mapping!
|
|
*
|
|
* The page does not need to be reserved.
|
|
*
|
|
* Usually this function is called from f_op->mmap() handler
|
|
* under mm->mmap_sem write-lock, so it can change vma->vm_flags.
|
|
* Caller must set VM_MIXEDMAP on vma if it wants to call this
|
|
* function from other places, for example from page-fault handler.
|
|
*/
|
|
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
|
|
struct page *page)
|
|
{
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return -EFAULT;
|
|
if (!page_count(page))
|
|
return -EINVAL;
|
|
if (!(vma->vm_flags & VM_MIXEDMAP)) {
|
|
BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
|
|
BUG_ON(vma->vm_flags & VM_PFNMAP);
|
|
vma->vm_flags |= VM_MIXEDMAP;
|
|
}
|
|
return insert_page(vma, addr, page, vma->vm_page_prot);
|
|
}
|
|
EXPORT_SYMBOL(vm_insert_page);
|
|
|
|
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
|
|
pfn_t pfn, pgprot_t prot)
|
|
{
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
int retval;
|
|
pte_t *pte, entry;
|
|
spinlock_t *ptl;
|
|
|
|
retval = -ENOMEM;
|
|
pte = get_locked_pte(mm, addr, &ptl);
|
|
if (!pte)
|
|
goto out;
|
|
retval = -EBUSY;
|
|
if (!pte_none(*pte))
|
|
goto out_unlock;
|
|
|
|
/* Ok, finally just insert the thing.. */
|
|
if (pfn_t_devmap(pfn))
|
|
entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
|
|
else
|
|
entry = pte_mkspecial(pfn_t_pte(pfn, prot));
|
|
set_pte_at(mm, addr, pte, entry);
|
|
update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
|
|
|
|
retval = 0;
|
|
out_unlock:
|
|
pte_unmap_unlock(pte, ptl);
|
|
out:
|
|
return retval;
|
|
}
|
|
|
|
/**
|
|
* vm_insert_pfn - insert single pfn into user vma
|
|
* @vma: user vma to map to
|
|
* @addr: target user address of this page
|
|
* @pfn: source kernel pfn
|
|
*
|
|
* Similar to vm_insert_page, this allows drivers to insert individual pages
|
|
* they've allocated into a user vma. Same comments apply.
|
|
*
|
|
* This function should only be called from a vm_ops->fault handler, and
|
|
* in that case the handler should return NULL.
|
|
*
|
|
* vma cannot be a COW mapping.
|
|
*
|
|
* As this is called only for pages that do not currently exist, we
|
|
* do not need to flush old virtual caches or the TLB.
|
|
*/
|
|
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
|
|
unsigned long pfn)
|
|
{
|
|
return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
|
|
}
|
|
EXPORT_SYMBOL(vm_insert_pfn);
|
|
|
|
/**
|
|
* vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
|
|
* @vma: user vma to map to
|
|
* @addr: target user address of this page
|
|
* @pfn: source kernel pfn
|
|
* @pgprot: pgprot flags for the inserted page
|
|
*
|
|
* This is exactly like vm_insert_pfn, except that it allows drivers to
|
|
* to override pgprot on a per-page basis.
|
|
*
|
|
* This only makes sense for IO mappings, and it makes no sense for
|
|
* cow mappings. In general, using multiple vmas is preferable;
|
|
* vm_insert_pfn_prot should only be used if using multiple VMAs is
|
|
* impractical.
|
|
*/
|
|
int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
|
|
unsigned long pfn, pgprot_t pgprot)
|
|
{
|
|
int ret;
|
|
/*
|
|
* Technically, architectures with pte_special can avoid all these
|
|
* restrictions (same for remap_pfn_range). However we would like
|
|
* consistency in testing and feature parity among all, so we should
|
|
* try to keep these invariants in place for everybody.
|
|
*/
|
|
BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
|
|
BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
|
|
(VM_PFNMAP|VM_MIXEDMAP));
|
|
BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
|
|
BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
|
|
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return -EFAULT;
|
|
if (track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)))
|
|
return -EINVAL;
|
|
|
|
ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(vm_insert_pfn_prot);
|
|
|
|
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
|
|
pfn_t pfn)
|
|
{
|
|
pgprot_t pgprot = vma->vm_page_prot;
|
|
|
|
BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
|
|
|
|
if (addr < vma->vm_start || addr >= vma->vm_end)
|
|
return -EFAULT;
|
|
if (track_pfn_insert(vma, &pgprot, pfn))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* If we don't have pte special, then we have to use the pfn_valid()
|
|
* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
|
|
* refcount the page if pfn_valid is true (hence insert_page rather
|
|
* than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
|
|
* without pte special, it would there be refcounted as a normal page.
|
|
*/
|
|
if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
|
|
struct page *page;
|
|
|
|
/*
|
|
* At this point we are committed to insert_page()
|
|
* regardless of whether the caller specified flags that
|
|
* result in pfn_t_has_page() == false.
|
|
*/
|
|
page = pfn_to_page(pfn_t_to_pfn(pfn));
|
|
return insert_page(vma, addr, page, pgprot);
|
|
}
|
|
return insert_pfn(vma, addr, pfn, pgprot);
|
|
}
|
|
EXPORT_SYMBOL(vm_insert_mixed);
|
|
|
|
/*
|
|
* maps a range of physical memory into the requested pages. the old
|
|
* mappings are removed. any references to nonexistent pages results
|
|
* in null mappings (currently treated as "copy-on-access")
|
|
*/
|
|
static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end,
|
|
unsigned long pfn, pgprot_t prot)
|
|
{
|
|
pte_t *pte;
|
|
spinlock_t *ptl;
|
|
|
|
pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
|
|
if (!pte)
|
|
return -ENOMEM;
|
|
arch_enter_lazy_mmu_mode();
|
|
do {
|
|
BUG_ON(!pte_none(*pte));
|
|
set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
|
|
pfn++;
|
|
} while (pte++, addr += PAGE_SIZE, addr != end);
|
|
arch_leave_lazy_mmu_mode();
|
|
pte_unmap_unlock(pte - 1, ptl);
|
|
return 0;
|
|
}
|
|
|
|
static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
|
|
unsigned long addr, unsigned long end,
|
|
unsigned long pfn, pgprot_t prot)
|
|
{
|
|
pmd_t *pmd;
|
|
unsigned long next;
|
|
|
|
pfn -= addr >> PAGE_SHIFT;
|
|
pmd = pmd_alloc(mm, pud, addr);
|
|
if (!pmd)
|
|
return -ENOMEM;
|
|
VM_BUG_ON(pmd_trans_huge(*pmd));
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
if (remap_pte_range(mm, pmd, addr, next,
|
|
pfn + (addr >> PAGE_SHIFT), prot))
|
|
return -ENOMEM;
|
|
} while (pmd++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
|
|
unsigned long addr, unsigned long end,
|
|
unsigned long pfn, pgprot_t prot)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
|
|
pfn -= addr >> PAGE_SHIFT;
|
|
pud = pud_alloc(mm, pgd, addr);
|
|
if (!pud)
|
|
return -ENOMEM;
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
if (remap_pmd_range(mm, pud, addr, next,
|
|
pfn + (addr >> PAGE_SHIFT), prot))
|
|
return -ENOMEM;
|
|
} while (pud++, addr = next, addr != end);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* remap_pfn_range - remap kernel memory to userspace
|
|
* @vma: user vma to map to
|
|
* @addr: target user address to start at
|
|
* @pfn: physical address of kernel memory
|
|
* @size: size of map area
|
|
* @prot: page protection flags for this mapping
|
|
*
|
|
* Note: this is only safe if the mm semaphore is held when called.
|
|
*/
|
|
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
|
|
unsigned long pfn, unsigned long size, pgprot_t prot)
|
|
{
|
|
pgd_t *pgd;
|
|
unsigned long next;
|
|
unsigned long end = addr + PAGE_ALIGN(size);
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
unsigned long remap_pfn = pfn;
|
|
int err;
|
|
|
|
/*
|
|
* Physically remapped pages are special. Tell the
|
|
* rest of the world about it:
|
|
* VM_IO tells people not to look at these pages
|
|
* (accesses can have side effects).
|
|
* VM_PFNMAP tells the core MM that the base pages are just
|
|
* raw PFN mappings, and do not have a "struct page" associated
|
|
* with them.
|
|
* VM_DONTEXPAND
|
|
* Disable vma merging and expanding with mremap().
|
|
* VM_DONTDUMP
|
|
* Omit vma from core dump, even when VM_IO turned off.
|
|
*
|
|
* There's a horrible special case to handle copy-on-write
|
|
* behaviour that some programs depend on. We mark the "original"
|
|
* un-COW'ed pages by matching them up with "vma->vm_pgoff".
|
|
* See vm_normal_page() for details.
|
|
*/
|
|
if (is_cow_mapping(vma->vm_flags)) {
|
|
if (addr != vma->vm_start || end != vma->vm_end)
|
|
return -EINVAL;
|
|
vma->vm_pgoff = pfn;
|
|
}
|
|
|
|
err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
|
|
if (err)
|
|
return -EINVAL;
|
|
|
|
vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
|
|
|
|
BUG_ON(addr >= end);
|
|
pfn -= addr >> PAGE_SHIFT;
|
|
pgd = pgd_offset(mm, addr);
|
|
flush_cache_range(vma, addr, end);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
err = remap_pud_range(mm, pgd, addr, next,
|
|
pfn + (addr >> PAGE_SHIFT), prot);
|
|
if (err)
|
|
break;
|
|
} while (pgd++, addr = next, addr != end);
|
|
|
|
if (err)
|
|
untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL(remap_pfn_range);
|
|
|
|
/**
|
|
* vm_iomap_memory - remap memory to userspace
|
|
* @vma: user vma to map to
|
|
* @start: start of area
|
|
* @len: size of area
|
|
*
|
|
* This is a simplified io_remap_pfn_range() for common driver use. The
|
|
* driver just needs to give us the physical memory range to be mapped,
|
|
* we'll figure out the rest from the vma information.
|
|
*
|
|
* NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
|
|
* whatever write-combining details or similar.
|
|
*/
|
|
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
|
|
{
|
|
unsigned long vm_len, pfn, pages;
|
|
|
|
/* Check that the physical memory area passed in looks valid */
|
|
if (start + len < start)
|
|
return -EINVAL;
|
|
/*
|
|
* You *really* shouldn't map things that aren't page-aligned,
|
|
* but we've historically allowed it because IO memory might
|
|
* just have smaller alignment.
|
|
*/
|
|
len += start & ~PAGE_MASK;
|
|
pfn = start >> PAGE_SHIFT;
|
|
pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
|
|
if (pfn + pages < pfn)
|
|
return -EINVAL;
|
|
|
|
/* We start the mapping 'vm_pgoff' pages into the area */
|
|
if (vma->vm_pgoff > pages)
|
|
return -EINVAL;
|
|
pfn += vma->vm_pgoff;
|
|
pages -= vma->vm_pgoff;
|
|
|
|
/* Can we fit all of the mapping? */
|
|
vm_len = vma->vm_end - vma->vm_start;
|
|
if (vm_len >> PAGE_SHIFT > pages)
|
|
return -EINVAL;
|
|
|
|
/* Ok, let it rip */
|
|
return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
|
|
}
|
|
EXPORT_SYMBOL(vm_iomap_memory);
|
|
|
|
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
|
|
unsigned long addr, unsigned long end,
|
|
pte_fn_t fn, void *data)
|
|
{
|
|
pte_t *pte;
|
|
int err;
|
|
pgtable_t token;
|
|
spinlock_t *uninitialized_var(ptl);
|
|
|
|
pte = (mm == &init_mm) ?
|
|
pte_alloc_kernel(pmd, addr) :
|
|
pte_alloc_map_lock(mm, pmd, addr, &ptl);
|
|
if (!pte)
|
|
return -ENOMEM;
|
|
|
|
BUG_ON(pmd_huge(*pmd));
|
|
|
|
arch_enter_lazy_mmu_mode();
|
|
|
|
token = pmd_pgtable(*pmd);
|
|
|
|
do {
|
|
err = fn(pte++, token, addr, data);
|
|
if (err)
|
|
break;
|
|
} while (addr += PAGE_SIZE, addr != end);
|
|
|
|
arch_leave_lazy_mmu_mode();
|
|
|
|
if (mm != &init_mm)
|
|
pte_unmap_unlock(pte-1, ptl);
|
|
return err;
|
|
}
|
|
|
|
static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
|
|
unsigned long addr, unsigned long end,
|
|
pte_fn_t fn, void *data)
|
|
{
|
|
pmd_t *pmd;
|
|
unsigned long next;
|
|
int err;
|
|
|
|
BUG_ON(pud_huge(*pud));
|
|
|
|
pmd = pmd_alloc(mm, pud, addr);
|
|
if (!pmd)
|
|
return -ENOMEM;
|
|
do {
|
|
next = pmd_addr_end(addr, end);
|
|
err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
|
|
if (err)
|
|
break;
|
|
} while (pmd++, addr = next, addr != end);
|
|
return err;
|
|
}
|
|
|
|
static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
|
|
unsigned long addr, unsigned long end,
|
|
pte_fn_t fn, void *data)
|
|
{
|
|
pud_t *pud;
|
|
unsigned long next;
|
|
int err;
|
|
|
|
pud = pud_alloc(mm, pgd, addr);
|
|
if (!pud)
|
|
return -ENOMEM;
|
|
do {
|
|
next = pud_addr_end(addr, end);
|
|
err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
|
|
if (err)
|
|
break;
|
|
} while (pud++, addr = next, addr != end);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* Scan a region of virtual memory, filling in page tables as necessary
|
|
* and calling a provided function on each leaf page table.
|
|
*/
|
|
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
|
|
unsigned long size, pte_fn_t fn, void *data)
|
|
{
|
|
pgd_t *pgd;
|
|
unsigned long next;
|
|
unsigned long end = addr + size;
|
|
int err;
|
|
|
|
if (WARN_ON(addr >= end))
|
|
return -EINVAL;
|
|
|
|
pgd = pgd_offset(mm, addr);
|
|
do {
|
|
next = pgd_addr_end(addr, end);
|
|
err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
|
|
if (err)
|
|
break;
|
|
} while (pgd++, addr = next, addr != end);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(apply_to_page_range);
|
|
|
|
/*
|
|
* handle_pte_fault chooses page fault handler according to an entry which was
|
|
* read non-atomically. Before making any commitment, on those architectures
|
|
* or configurations (e.g. i386 with PAE) which might give a mix of unmatched
|
|
* parts, do_swap_page must check under lock before unmapping the pte and
|
|
* proceeding (but do_wp_page is only called after already making such a check;
|
|
* and do_anonymous_page can safely check later on).
|
|
*/
|
|
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
|
|
pte_t *page_table, pte_t orig_pte)
|
|
{
|
|
int same = 1;
|
|
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
|
|
if (sizeof(pte_t) > sizeof(unsigned long)) {
|
|
spinlock_t *ptl = pte_lockptr(mm, pmd);
|
|
spin_lock(ptl);
|
|
same = pte_same(*page_table, orig_pte);
|
|
spin_unlock(ptl);
|
|
}
|
|
#endif
|
|
pte_unmap(page_table);
|
|
return same;
|
|
}
|
|
|
|
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
|
|
{
|
|
debug_dma_assert_idle(src);
|
|
|
|
/*
|
|
* If the source page was a PFN mapping, we don't have
|
|
* a "struct page" for it. We do a best-effort copy by
|
|
* just copying from the original user address. If that
|
|
* fails, we just zero-fill it. Live with it.
|
|
*/
|
|
if (unlikely(!src)) {
|
|
void *kaddr = kmap_atomic(dst);
|
|
void __user *uaddr = (void __user *)(va & PAGE_MASK);
|
|
|
|
/*
|
|
* This really shouldn't fail, because the page is there
|
|
* in the page tables. But it might just be unreadable,
|
|
* in which case we just give up and fill the result with
|
|
* zeroes.
|
|
*/
|
|
if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
|
|
clear_page(kaddr);
|
|
kunmap_atomic(kaddr);
|
|
flush_dcache_page(dst);
|
|
} else
|
|
copy_user_highpage(dst, src, va, vma);
|
|
}
|
|
|
|
static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
|
|
{
|
|
struct file *vm_file = vma->vm_file;
|
|
|
|
if (vm_file)
|
|
return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
|
|
|
|
/*
|
|
* Special mappings (e.g. VDSO) do not have any file so fake
|
|
* a default GFP_KERNEL for them.
|
|
*/
|
|
return GFP_KERNEL;
|
|
}
|
|
|
|
/*
|
|
* Notify the address space that the page is about to become writable so that
|
|
* it can prohibit this or wait for the page to get into an appropriate state.
|
|
*
|
|
* We do this without the lock held, so that it can sleep if it needs to.
|
|
*/
|
|
static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
|
|
unsigned long address)
|
|
{
|
|
struct vm_fault vmf;
|
|
int ret;
|
|
|
|
vmf.virtual_address = (void __user *)(address & PAGE_MASK);
|
|
vmf.pgoff = page->index;
|
|
vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
|
|
vmf.gfp_mask = __get_fault_gfp_mask(vma);
|
|
vmf.page = page;
|
|
vmf.cow_page = NULL;
|
|
|
|
ret = vma->vm_ops->page_mkwrite(vma, &vmf);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
|
|
return ret;
|
|
if (unlikely(!(ret & VM_FAULT_LOCKED))) {
|
|
lock_page(page);
|
|
if (!page->mapping) {
|
|
unlock_page(page);
|
|
return 0; /* retry */
|
|
}
|
|
ret |= VM_FAULT_LOCKED;
|
|
} else
|
|
VM_BUG_ON_PAGE(!PageLocked(page), page);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Handle write page faults for pages that can be reused in the current vma
|
|
*
|
|
* This can happen either due to the mapping being with the VM_SHARED flag,
|
|
* or due to us being the last reference standing to the page. In either
|
|
* case, all we need to do here is to mark the page as writable and update
|
|
* any related book-keeping.
|
|
*/
|
|
static inline int wp_page_reuse(struct fault_env *fe, pte_t orig_pte,
|
|
struct page *page, int page_mkwrite, int dirty_shared)
|
|
__releases(fe->ptl)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
pte_t entry;
|
|
/*
|
|
* Clear the pages cpupid information as the existing
|
|
* information potentially belongs to a now completely
|
|
* unrelated process.
|
|
*/
|
|
if (page)
|
|
page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
|
|
|
|
flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
|
|
entry = pte_mkyoung(orig_pte);
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
if (ptep_set_access_flags(vma, fe->address, fe->pte, entry, 1))
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
|
|
if (dirty_shared) {
|
|
struct address_space *mapping;
|
|
int dirtied;
|
|
|
|
if (!page_mkwrite)
|
|
lock_page(page);
|
|
|
|
dirtied = set_page_dirty(page);
|
|
VM_BUG_ON_PAGE(PageAnon(page), page);
|
|
mapping = page->mapping;
|
|
unlock_page(page);
|
|
put_page(page);
|
|
|
|
if ((dirtied || page_mkwrite) && mapping) {
|
|
/*
|
|
* Some device drivers do not set page.mapping
|
|
* but still dirty their pages
|
|
*/
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
}
|
|
|
|
if (!page_mkwrite)
|
|
file_update_time(vma->vm_file);
|
|
}
|
|
|
|
return VM_FAULT_WRITE;
|
|
}
|
|
|
|
/*
|
|
* Handle the case of a page which we actually need to copy to a new page.
|
|
*
|
|
* Called with mmap_sem locked and the old page referenced, but
|
|
* without the ptl held.
|
|
*
|
|
* High level logic flow:
|
|
*
|
|
* - Allocate a page, copy the content of the old page to the new one.
|
|
* - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
|
|
* - Take the PTL. If the pte changed, bail out and release the allocated page
|
|
* - If the pte is still the way we remember it, update the page table and all
|
|
* relevant references. This includes dropping the reference the page-table
|
|
* held to the old page, as well as updating the rmap.
|
|
* - In any case, unlock the PTL and drop the reference we took to the old page.
|
|
*/
|
|
static int wp_page_copy(struct fault_env *fe, pte_t orig_pte,
|
|
struct page *old_page)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
struct page *new_page = NULL;
|
|
pte_t entry;
|
|
int page_copied = 0;
|
|
const unsigned long mmun_start = fe->address & PAGE_MASK;
|
|
const unsigned long mmun_end = mmun_start + PAGE_SIZE;
|
|
struct mem_cgroup *memcg;
|
|
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
goto oom;
|
|
|
|
if (is_zero_pfn(pte_pfn(orig_pte))) {
|
|
new_page = alloc_zeroed_user_highpage_movable(vma, fe->address);
|
|
if (!new_page)
|
|
goto oom;
|
|
} else {
|
|
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
|
|
fe->address);
|
|
if (!new_page)
|
|
goto oom;
|
|
cow_user_page(new_page, old_page, fe->address, vma);
|
|
}
|
|
|
|
if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
|
|
goto oom_free_new;
|
|
|
|
__SetPageUptodate(new_page);
|
|
|
|
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
|
|
|
|
/*
|
|
* Re-check the pte - we dropped the lock
|
|
*/
|
|
fe->pte = pte_offset_map_lock(mm, fe->pmd, fe->address, &fe->ptl);
|
|
if (likely(pte_same(*fe->pte, orig_pte))) {
|
|
if (old_page) {
|
|
if (!PageAnon(old_page)) {
|
|
dec_mm_counter_fast(mm,
|
|
mm_counter_file(old_page));
|
|
inc_mm_counter_fast(mm, MM_ANONPAGES);
|
|
}
|
|
} else {
|
|
inc_mm_counter_fast(mm, MM_ANONPAGES);
|
|
}
|
|
flush_cache_page(vma, fe->address, pte_pfn(orig_pte));
|
|
entry = mk_pte(new_page, vma->vm_page_prot);
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
/*
|
|
* Clear the pte entry and flush it first, before updating the
|
|
* pte with the new entry. This will avoid a race condition
|
|
* seen in the presence of one thread doing SMC and another
|
|
* thread doing COW.
|
|
*/
|
|
ptep_clear_flush_notify(vma, fe->address, fe->pte);
|
|
page_add_new_anon_rmap(new_page, vma, fe->address, false);
|
|
mem_cgroup_commit_charge(new_page, memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(new_page, vma);
|
|
/*
|
|
* We call the notify macro here because, when using secondary
|
|
* mmu page tables (such as kvm shadow page tables), we want the
|
|
* new page to be mapped directly into the secondary page table.
|
|
*/
|
|
set_pte_at_notify(mm, fe->address, fe->pte, entry);
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
if (old_page) {
|
|
/*
|
|
* Only after switching the pte to the new page may
|
|
* we remove the mapcount here. Otherwise another
|
|
* process may come and find the rmap count decremented
|
|
* before the pte is switched to the new page, and
|
|
* "reuse" the old page writing into it while our pte
|
|
* here still points into it and can be read by other
|
|
* threads.
|
|
*
|
|
* The critical issue is to order this
|
|
* page_remove_rmap with the ptp_clear_flush above.
|
|
* Those stores are ordered by (if nothing else,)
|
|
* the barrier present in the atomic_add_negative
|
|
* in page_remove_rmap.
|
|
*
|
|
* Then the TLB flush in ptep_clear_flush ensures that
|
|
* no process can access the old page before the
|
|
* decremented mapcount is visible. And the old page
|
|
* cannot be reused until after the decremented
|
|
* mapcount is visible. So transitively, TLBs to
|
|
* old page will be flushed before it can be reused.
|
|
*/
|
|
page_remove_rmap(old_page, false);
|
|
}
|
|
|
|
/* Free the old page.. */
|
|
new_page = old_page;
|
|
page_copied = 1;
|
|
} else {
|
|
mem_cgroup_cancel_charge(new_page, memcg, false);
|
|
}
|
|
|
|
if (new_page)
|
|
put_page(new_page);
|
|
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
|
|
if (old_page) {
|
|
/*
|
|
* Don't let another task, with possibly unlocked vma,
|
|
* keep the mlocked page.
|
|
*/
|
|
if (page_copied && (vma->vm_flags & VM_LOCKED)) {
|
|
lock_page(old_page); /* LRU manipulation */
|
|
if (PageMlocked(old_page))
|
|
munlock_vma_page(old_page);
|
|
unlock_page(old_page);
|
|
}
|
|
put_page(old_page);
|
|
}
|
|
return page_copied ? VM_FAULT_WRITE : 0;
|
|
oom_free_new:
|
|
put_page(new_page);
|
|
oom:
|
|
if (old_page)
|
|
put_page(old_page);
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
/*
|
|
* Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
|
|
* mapping
|
|
*/
|
|
static int wp_pfn_shared(struct fault_env *fe, pte_t orig_pte)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
|
|
if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
|
|
struct vm_fault vmf = {
|
|
.page = NULL,
|
|
.pgoff = linear_page_index(vma, fe->address),
|
|
.virtual_address =
|
|
(void __user *)(fe->address & PAGE_MASK),
|
|
.flags = FAULT_FLAG_WRITE | FAULT_FLAG_MKWRITE,
|
|
};
|
|
int ret;
|
|
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
ret = vma->vm_ops->pfn_mkwrite(vma, &vmf);
|
|
if (ret & VM_FAULT_ERROR)
|
|
return ret;
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
/*
|
|
* We might have raced with another page fault while we
|
|
* released the pte_offset_map_lock.
|
|
*/
|
|
if (!pte_same(*fe->pte, orig_pte)) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return 0;
|
|
}
|
|
}
|
|
return wp_page_reuse(fe, orig_pte, NULL, 0, 0);
|
|
}
|
|
|
|
static int wp_page_shared(struct fault_env *fe, pte_t orig_pte,
|
|
struct page *old_page)
|
|
__releases(fe->ptl)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
int page_mkwrite = 0;
|
|
|
|
get_page(old_page);
|
|
|
|
if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
|
|
int tmp;
|
|
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
tmp = do_page_mkwrite(vma, old_page, fe->address);
|
|
if (unlikely(!tmp || (tmp &
|
|
(VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
|
|
put_page(old_page);
|
|
return tmp;
|
|
}
|
|
/*
|
|
* Since we dropped the lock we need to revalidate
|
|
* the PTE as someone else may have changed it. If
|
|
* they did, we just return, as we can count on the
|
|
* MMU to tell us if they didn't also make it writable.
|
|
*/
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
if (!pte_same(*fe->pte, orig_pte)) {
|
|
unlock_page(old_page);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
put_page(old_page);
|
|
return 0;
|
|
}
|
|
page_mkwrite = 1;
|
|
}
|
|
|
|
return wp_page_reuse(fe, orig_pte, old_page, page_mkwrite, 1);
|
|
}
|
|
|
|
/*
|
|
* This routine handles present pages, when users try to write
|
|
* to a shared page. It is done by copying the page to a new address
|
|
* and decrementing the shared-page counter for the old page.
|
|
*
|
|
* Note that this routine assumes that the protection checks have been
|
|
* done by the caller (the low-level page fault routine in most cases).
|
|
* Thus we can safely just mark it writable once we've done any necessary
|
|
* COW.
|
|
*
|
|
* We also mark the page dirty at this point even though the page will
|
|
* change only once the write actually happens. This avoids a few races,
|
|
* and potentially makes it more efficient.
|
|
*
|
|
* We enter with non-exclusive mmap_sem (to exclude vma changes,
|
|
* but allow concurrent faults), with pte both mapped and locked.
|
|
* We return with mmap_sem still held, but pte unmapped and unlocked.
|
|
*/
|
|
static int do_wp_page(struct fault_env *fe, pte_t orig_pte)
|
|
__releases(fe->ptl)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *old_page;
|
|
|
|
old_page = vm_normal_page(vma, fe->address, orig_pte);
|
|
if (!old_page) {
|
|
/*
|
|
* VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
|
|
* VM_PFNMAP VMA.
|
|
*
|
|
* We should not cow pages in a shared writeable mapping.
|
|
* Just mark the pages writable and/or call ops->pfn_mkwrite.
|
|
*/
|
|
if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
|
|
(VM_WRITE|VM_SHARED))
|
|
return wp_pfn_shared(fe, orig_pte);
|
|
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return wp_page_copy(fe, orig_pte, old_page);
|
|
}
|
|
|
|
/*
|
|
* Take out anonymous pages first, anonymous shared vmas are
|
|
* not dirty accountable.
|
|
*/
|
|
if (PageAnon(old_page) && !PageKsm(old_page)) {
|
|
int total_mapcount;
|
|
if (!trylock_page(old_page)) {
|
|
get_page(old_page);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
lock_page(old_page);
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
|
|
fe->address, &fe->ptl);
|
|
if (!pte_same(*fe->pte, orig_pte)) {
|
|
unlock_page(old_page);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
put_page(old_page);
|
|
return 0;
|
|
}
|
|
put_page(old_page);
|
|
}
|
|
if (reuse_swap_page(old_page, &total_mapcount)) {
|
|
if (total_mapcount == 1) {
|
|
/*
|
|
* The page is all ours. Move it to
|
|
* our anon_vma so the rmap code will
|
|
* not search our parent or siblings.
|
|
* Protected against the rmap code by
|
|
* the page lock.
|
|
*/
|
|
page_move_anon_rmap(old_page, vma);
|
|
}
|
|
unlock_page(old_page);
|
|
return wp_page_reuse(fe, orig_pte, old_page, 0, 0);
|
|
}
|
|
unlock_page(old_page);
|
|
} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
|
|
(VM_WRITE|VM_SHARED))) {
|
|
return wp_page_shared(fe, orig_pte, old_page);
|
|
}
|
|
|
|
/*
|
|
* Ok, we need to copy. Oh, well..
|
|
*/
|
|
get_page(old_page);
|
|
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return wp_page_copy(fe, orig_pte, old_page);
|
|
}
|
|
|
|
static void unmap_mapping_range_vma(struct vm_area_struct *vma,
|
|
unsigned long start_addr, unsigned long end_addr,
|
|
struct zap_details *details)
|
|
{
|
|
zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
|
|
}
|
|
|
|
static inline void unmap_mapping_range_tree(struct rb_root *root,
|
|
struct zap_details *details)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
pgoff_t vba, vea, zba, zea;
|
|
|
|
vma_interval_tree_foreach(vma, root,
|
|
details->first_index, details->last_index) {
|
|
|
|
vba = vma->vm_pgoff;
|
|
vea = vba + vma_pages(vma) - 1;
|
|
zba = details->first_index;
|
|
if (zba < vba)
|
|
zba = vba;
|
|
zea = details->last_index;
|
|
if (zea > vea)
|
|
zea = vea;
|
|
|
|
unmap_mapping_range_vma(vma,
|
|
((zba - vba) << PAGE_SHIFT) + vma->vm_start,
|
|
((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
|
|
details);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* unmap_mapping_range - unmap the portion of all mmaps in the specified
|
|
* address_space corresponding to the specified page range in the underlying
|
|
* file.
|
|
*
|
|
* @mapping: the address space containing mmaps to be unmapped.
|
|
* @holebegin: byte in first page to unmap, relative to the start of
|
|
* the underlying file. This will be rounded down to a PAGE_SIZE
|
|
* boundary. Note that this is different from truncate_pagecache(), which
|
|
* must keep the partial page. In contrast, we must get rid of
|
|
* partial pages.
|
|
* @holelen: size of prospective hole in bytes. This will be rounded
|
|
* up to a PAGE_SIZE boundary. A holelen of zero truncates to the
|
|
* end of the file.
|
|
* @even_cows: 1 when truncating a file, unmap even private COWed pages;
|
|
* but 0 when invalidating pagecache, don't throw away private data.
|
|
*/
|
|
void unmap_mapping_range(struct address_space *mapping,
|
|
loff_t const holebegin, loff_t const holelen, int even_cows)
|
|
{
|
|
struct zap_details details = { };
|
|
pgoff_t hba = holebegin >> PAGE_SHIFT;
|
|
pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
|
|
/* Check for overflow. */
|
|
if (sizeof(holelen) > sizeof(hlen)) {
|
|
long long holeend =
|
|
(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
|
|
if (holeend & ~(long long)ULONG_MAX)
|
|
hlen = ULONG_MAX - hba + 1;
|
|
}
|
|
|
|
details.check_mapping = even_cows? NULL: mapping;
|
|
details.first_index = hba;
|
|
details.last_index = hba + hlen - 1;
|
|
if (details.last_index < details.first_index)
|
|
details.last_index = ULONG_MAX;
|
|
|
|
i_mmap_lock_write(mapping);
|
|
if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
|
|
unmap_mapping_range_tree(&mapping->i_mmap, &details);
|
|
i_mmap_unlock_write(mapping);
|
|
}
|
|
EXPORT_SYMBOL(unmap_mapping_range);
|
|
|
|
/*
|
|
* We enter with non-exclusive mmap_sem (to exclude vma changes,
|
|
* but allow concurrent faults), and pte mapped but not yet locked.
|
|
* We return with pte unmapped and unlocked.
|
|
*
|
|
* We return with the mmap_sem locked or unlocked in the same cases
|
|
* as does filemap_fault().
|
|
*/
|
|
int do_swap_page(struct fault_env *fe, pte_t orig_pte)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *page, *swapcache;
|
|
struct mem_cgroup *memcg;
|
|
swp_entry_t entry;
|
|
pte_t pte;
|
|
int locked;
|
|
int exclusive = 0;
|
|
int ret = 0;
|
|
|
|
if (!pte_unmap_same(vma->vm_mm, fe->pmd, fe->pte, orig_pte))
|
|
goto out;
|
|
|
|
entry = pte_to_swp_entry(orig_pte);
|
|
if (unlikely(non_swap_entry(entry))) {
|
|
if (is_migration_entry(entry)) {
|
|
migration_entry_wait(vma->vm_mm, fe->pmd, fe->address);
|
|
} else if (is_hwpoison_entry(entry)) {
|
|
ret = VM_FAULT_HWPOISON;
|
|
} else {
|
|
print_bad_pte(vma, fe->address, orig_pte, NULL);
|
|
ret = VM_FAULT_SIGBUS;
|
|
}
|
|
goto out;
|
|
}
|
|
delayacct_set_flag(DELAYACCT_PF_SWAPIN);
|
|
page = lookup_swap_cache(entry);
|
|
if (!page) {
|
|
page = swapin_readahead(entry,
|
|
GFP_HIGHUSER_MOVABLE, vma, fe->address);
|
|
if (!page) {
|
|
/*
|
|
* Back out if somebody else faulted in this pte
|
|
* while we released the pte lock.
|
|
*/
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd,
|
|
fe->address, &fe->ptl);
|
|
if (likely(pte_same(*fe->pte, orig_pte)))
|
|
ret = VM_FAULT_OOM;
|
|
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
|
|
goto unlock;
|
|
}
|
|
|
|
/* Had to read the page from swap area: Major fault */
|
|
ret = VM_FAULT_MAJOR;
|
|
count_vm_event(PGMAJFAULT);
|
|
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
|
|
} else if (PageHWPoison(page)) {
|
|
/*
|
|
* hwpoisoned dirty swapcache pages are kept for killing
|
|
* owner processes (which may be unknown at hwpoison time)
|
|
*/
|
|
ret = VM_FAULT_HWPOISON;
|
|
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
|
|
swapcache = page;
|
|
goto out_release;
|
|
}
|
|
|
|
swapcache = page;
|
|
locked = lock_page_or_retry(page, vma->vm_mm, fe->flags);
|
|
|
|
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
|
|
if (!locked) {
|
|
ret |= VM_FAULT_RETRY;
|
|
goto out_release;
|
|
}
|
|
|
|
/*
|
|
* Make sure try_to_free_swap or reuse_swap_page or swapoff did not
|
|
* release the swapcache from under us. The page pin, and pte_same
|
|
* test below, are not enough to exclude that. Even if it is still
|
|
* swapcache, we need to check that the page's swap has not changed.
|
|
*/
|
|
if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
|
|
goto out_page;
|
|
|
|
page = ksm_might_need_to_copy(page, vma, fe->address);
|
|
if (unlikely(!page)) {
|
|
ret = VM_FAULT_OOM;
|
|
page = swapcache;
|
|
goto out_page;
|
|
}
|
|
|
|
if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
|
|
&memcg, false)) {
|
|
ret = VM_FAULT_OOM;
|
|
goto out_page;
|
|
}
|
|
|
|
/*
|
|
* Back out if somebody else already faulted in this pte.
|
|
*/
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
if (unlikely(!pte_same(*fe->pte, orig_pte)))
|
|
goto out_nomap;
|
|
|
|
if (unlikely(!PageUptodate(page))) {
|
|
ret = VM_FAULT_SIGBUS;
|
|
goto out_nomap;
|
|
}
|
|
|
|
/*
|
|
* The page isn't present yet, go ahead with the fault.
|
|
*
|
|
* Be careful about the sequence of operations here.
|
|
* To get its accounting right, reuse_swap_page() must be called
|
|
* while the page is counted on swap but not yet in mapcount i.e.
|
|
* before page_add_anon_rmap() and swap_free(); try_to_free_swap()
|
|
* must be called after the swap_free(), or it will never succeed.
|
|
*/
|
|
|
|
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
|
|
dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
|
|
pte = mk_pte(page, vma->vm_page_prot);
|
|
if ((fe->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
|
|
pte = maybe_mkwrite(pte_mkdirty(pte), vma);
|
|
fe->flags &= ~FAULT_FLAG_WRITE;
|
|
ret |= VM_FAULT_WRITE;
|
|
exclusive = RMAP_EXCLUSIVE;
|
|
}
|
|
flush_icache_page(vma, page);
|
|
if (pte_swp_soft_dirty(orig_pte))
|
|
pte = pte_mksoft_dirty(pte);
|
|
set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
|
|
if (page == swapcache) {
|
|
do_page_add_anon_rmap(page, vma, fe->address, exclusive);
|
|
mem_cgroup_commit_charge(page, memcg, true, false);
|
|
activate_page(page);
|
|
} else { /* ksm created a completely new copy */
|
|
page_add_new_anon_rmap(page, vma, fe->address, false);
|
|
mem_cgroup_commit_charge(page, memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(page, vma);
|
|
}
|
|
|
|
swap_free(entry);
|
|
if (mem_cgroup_swap_full(page) ||
|
|
(vma->vm_flags & VM_LOCKED) || PageMlocked(page))
|
|
try_to_free_swap(page);
|
|
unlock_page(page);
|
|
if (page != swapcache) {
|
|
/*
|
|
* Hold the lock to avoid the swap entry to be reused
|
|
* until we take the PT lock for the pte_same() check
|
|
* (to avoid false positives from pte_same). For
|
|
* further safety release the lock after the swap_free
|
|
* so that the swap count won't change under a
|
|
* parallel locked swapcache.
|
|
*/
|
|
unlock_page(swapcache);
|
|
put_page(swapcache);
|
|
}
|
|
|
|
if (fe->flags & FAULT_FLAG_WRITE) {
|
|
ret |= do_wp_page(fe, pte);
|
|
if (ret & VM_FAULT_ERROR)
|
|
ret &= VM_FAULT_ERROR;
|
|
goto out;
|
|
}
|
|
|
|
/* No need to invalidate - it was non-present before */
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
unlock:
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
out:
|
|
return ret;
|
|
out_nomap:
|
|
mem_cgroup_cancel_charge(page, memcg, false);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
out_page:
|
|
unlock_page(page);
|
|
out_release:
|
|
put_page(page);
|
|
if (page != swapcache) {
|
|
unlock_page(swapcache);
|
|
put_page(swapcache);
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* This is like a special single-page "expand_{down|up}wards()",
|
|
* except we must first make sure that 'address{-|+}PAGE_SIZE'
|
|
* doesn't hit another vma.
|
|
*/
|
|
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
|
|
{
|
|
address &= PAGE_MASK;
|
|
if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
|
|
struct vm_area_struct *prev = vma->vm_prev;
|
|
|
|
/*
|
|
* Is there a mapping abutting this one below?
|
|
*
|
|
* That's only ok if it's the same stack mapping
|
|
* that has gotten split..
|
|
*/
|
|
if (prev && prev->vm_end == address)
|
|
return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
|
|
|
|
return expand_downwards(vma, address - PAGE_SIZE);
|
|
}
|
|
if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
|
|
struct vm_area_struct *next = vma->vm_next;
|
|
|
|
/* As VM_GROWSDOWN but s/below/above/ */
|
|
if (next && next->vm_start == address + PAGE_SIZE)
|
|
return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
|
|
|
|
return expand_upwards(vma, address + PAGE_SIZE);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* We enter with non-exclusive mmap_sem (to exclude vma changes,
|
|
* but allow concurrent faults), and pte mapped but not yet locked.
|
|
* We return with mmap_sem still held, but pte unmapped and unlocked.
|
|
*/
|
|
static int do_anonymous_page(struct fault_env *fe)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct mem_cgroup *memcg;
|
|
struct page *page;
|
|
pte_t entry;
|
|
|
|
/* File mapping without ->vm_ops ? */
|
|
if (vma->vm_flags & VM_SHARED)
|
|
return VM_FAULT_SIGBUS;
|
|
|
|
/* Check if we need to add a guard page to the stack */
|
|
if (check_stack_guard_page(vma, fe->address) < 0)
|
|
return VM_FAULT_SIGSEGV;
|
|
|
|
/*
|
|
* Use pte_alloc() instead of pte_alloc_map(). We can't run
|
|
* pte_offset_map() on pmds where a huge pmd might be created
|
|
* from a different thread.
|
|
*
|
|
* pte_alloc_map() is safe to use under down_write(mmap_sem) or when
|
|
* parallel threads are excluded by other means.
|
|
*
|
|
* Here we only have down_read(mmap_sem).
|
|
*/
|
|
if (pte_alloc(vma->vm_mm, fe->pmd, fe->address))
|
|
return VM_FAULT_OOM;
|
|
|
|
/* See the comment in pte_alloc_one_map() */
|
|
if (unlikely(pmd_trans_unstable(fe->pmd)))
|
|
return 0;
|
|
|
|
/* Use the zero-page for reads */
|
|
if (!(fe->flags & FAULT_FLAG_WRITE) &&
|
|
!mm_forbids_zeropage(vma->vm_mm)) {
|
|
entry = pte_mkspecial(pfn_pte(my_zero_pfn(fe->address),
|
|
vma->vm_page_prot));
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
if (!pte_none(*fe->pte))
|
|
goto unlock;
|
|
/* Deliver the page fault to userland, check inside PT lock */
|
|
if (userfaultfd_missing(vma)) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return handle_userfault(fe, VM_UFFD_MISSING);
|
|
}
|
|
goto setpte;
|
|
}
|
|
|
|
/* Allocate our own private page. */
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
goto oom;
|
|
page = alloc_zeroed_user_highpage_movable(vma, fe->address);
|
|
if (!page)
|
|
goto oom;
|
|
|
|
if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
|
|
goto oom_free_page;
|
|
|
|
/*
|
|
* The memory barrier inside __SetPageUptodate makes sure that
|
|
* preceeding stores to the page contents become visible before
|
|
* the set_pte_at() write.
|
|
*/
|
|
__SetPageUptodate(page);
|
|
|
|
entry = mk_pte(page, vma->vm_page_prot);
|
|
if (vma->vm_flags & VM_WRITE)
|
|
entry = pte_mkwrite(pte_mkdirty(entry));
|
|
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
if (!pte_none(*fe->pte))
|
|
goto release;
|
|
|
|
/* Deliver the page fault to userland, check inside PT lock */
|
|
if (userfaultfd_missing(vma)) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
mem_cgroup_cancel_charge(page, memcg, false);
|
|
put_page(page);
|
|
return handle_userfault(fe, VM_UFFD_MISSING);
|
|
}
|
|
|
|
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
|
|
page_add_new_anon_rmap(page, vma, fe->address, false);
|
|
mem_cgroup_commit_charge(page, memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(page, vma);
|
|
setpte:
|
|
set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
|
|
|
|
/* No need to invalidate - it was non-present before */
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
unlock:
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return 0;
|
|
release:
|
|
mem_cgroup_cancel_charge(page, memcg, false);
|
|
put_page(page);
|
|
goto unlock;
|
|
oom_free_page:
|
|
put_page(page);
|
|
oom:
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
/*
|
|
* The mmap_sem must have been held on entry, and may have been
|
|
* released depending on flags and vma->vm_ops->fault() return value.
|
|
* See filemap_fault() and __lock_page_retry().
|
|
*/
|
|
static int __do_fault(struct fault_env *fe, pgoff_t pgoff,
|
|
struct page *cow_page, struct page **page, void **entry)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct vm_fault vmf;
|
|
int ret;
|
|
|
|
vmf.virtual_address = (void __user *)(fe->address & PAGE_MASK);
|
|
vmf.pgoff = pgoff;
|
|
vmf.flags = fe->flags;
|
|
vmf.page = NULL;
|
|
vmf.gfp_mask = __get_fault_gfp_mask(vma);
|
|
vmf.cow_page = cow_page;
|
|
|
|
ret = vma->vm_ops->fault(vma, &vmf);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
return ret;
|
|
if (ret & VM_FAULT_DAX_LOCKED) {
|
|
*entry = vmf.entry;
|
|
return ret;
|
|
}
|
|
|
|
if (unlikely(PageHWPoison(vmf.page))) {
|
|
if (ret & VM_FAULT_LOCKED)
|
|
unlock_page(vmf.page);
|
|
put_page(vmf.page);
|
|
return VM_FAULT_HWPOISON;
|
|
}
|
|
|
|
if (unlikely(!(ret & VM_FAULT_LOCKED)))
|
|
lock_page(vmf.page);
|
|
else
|
|
VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
|
|
|
|
*page = vmf.page;
|
|
return ret;
|
|
}
|
|
|
|
static int pte_alloc_one_map(struct fault_env *fe)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
|
|
if (!pmd_none(*fe->pmd))
|
|
goto map_pte;
|
|
if (fe->prealloc_pte) {
|
|
fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
|
|
if (unlikely(!pmd_none(*fe->pmd))) {
|
|
spin_unlock(fe->ptl);
|
|
goto map_pte;
|
|
}
|
|
|
|
atomic_long_inc(&vma->vm_mm->nr_ptes);
|
|
pmd_populate(vma->vm_mm, fe->pmd, fe->prealloc_pte);
|
|
spin_unlock(fe->ptl);
|
|
fe->prealloc_pte = 0;
|
|
} else if (unlikely(pte_alloc(vma->vm_mm, fe->pmd, fe->address))) {
|
|
return VM_FAULT_OOM;
|
|
}
|
|
map_pte:
|
|
/*
|
|
* If a huge pmd materialized under us just retry later. Use
|
|
* pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd
|
|
* didn't become pmd_trans_huge under us and then back to pmd_none, as
|
|
* a result of MADV_DONTNEED running immediately after a huge pmd fault
|
|
* in a different thread of this mm, in turn leading to a misleading
|
|
* pmd_trans_huge() retval. All we have to ensure is that it is a
|
|
* regular pmd that we can walk with pte_offset_map() and we can do that
|
|
* through an atomic read in C, which is what pmd_trans_unstable()
|
|
* provides.
|
|
*/
|
|
if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
|
|
return VM_FAULT_NOPAGE;
|
|
|
|
fe->pte = pte_offset_map_lock(vma->vm_mm, fe->pmd, fe->address,
|
|
&fe->ptl);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
|
|
|
|
#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
|
|
static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
|
|
unsigned long haddr)
|
|
{
|
|
if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
|
|
(vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
|
|
return false;
|
|
if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
|
|
return false;
|
|
return true;
|
|
}
|
|
|
|
static int do_set_pmd(struct fault_env *fe, struct page *page)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
bool write = fe->flags & FAULT_FLAG_WRITE;
|
|
unsigned long haddr = fe->address & HPAGE_PMD_MASK;
|
|
pmd_t entry;
|
|
int i, ret;
|
|
|
|
if (!transhuge_vma_suitable(vma, haddr))
|
|
return VM_FAULT_FALLBACK;
|
|
|
|
ret = VM_FAULT_FALLBACK;
|
|
page = compound_head(page);
|
|
|
|
fe->ptl = pmd_lock(vma->vm_mm, fe->pmd);
|
|
if (unlikely(!pmd_none(*fe->pmd)))
|
|
goto out;
|
|
|
|
for (i = 0; i < HPAGE_PMD_NR; i++)
|
|
flush_icache_page(vma, page + i);
|
|
|
|
entry = mk_huge_pmd(page, vma->vm_page_prot);
|
|
if (write)
|
|
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
|
|
|
|
add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
|
|
page_add_file_rmap(page, true);
|
|
|
|
set_pmd_at(vma->vm_mm, haddr, fe->pmd, entry);
|
|
|
|
update_mmu_cache_pmd(vma, haddr, fe->pmd);
|
|
|
|
/* fault is handled */
|
|
ret = 0;
|
|
count_vm_event(THP_FILE_MAPPED);
|
|
out:
|
|
spin_unlock(fe->ptl);
|
|
return ret;
|
|
}
|
|
#else
|
|
static int do_set_pmd(struct fault_env *fe, struct page *page)
|
|
{
|
|
BUILD_BUG();
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* alloc_set_pte - setup new PTE entry for given page and add reverse page
|
|
* mapping. If needed, the fucntion allocates page table or use pre-allocated.
|
|
*
|
|
* @fe: fault environment
|
|
* @memcg: memcg to charge page (only for private mappings)
|
|
* @page: page to map
|
|
*
|
|
* Caller must take care of unlocking fe->ptl, if fe->pte is non-NULL on return.
|
|
*
|
|
* Target users are page handler itself and implementations of
|
|
* vm_ops->map_pages.
|
|
*/
|
|
int alloc_set_pte(struct fault_env *fe, struct mem_cgroup *memcg,
|
|
struct page *page)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
bool write = fe->flags & FAULT_FLAG_WRITE;
|
|
pte_t entry;
|
|
int ret;
|
|
|
|
if (pmd_none(*fe->pmd) && PageTransCompound(page) &&
|
|
IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
|
|
/* THP on COW? */
|
|
VM_BUG_ON_PAGE(memcg, page);
|
|
|
|
ret = do_set_pmd(fe, page);
|
|
if (ret != VM_FAULT_FALLBACK)
|
|
return ret;
|
|
}
|
|
|
|
if (!fe->pte) {
|
|
ret = pte_alloc_one_map(fe);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
/* Re-check under ptl */
|
|
if (unlikely(!pte_none(*fe->pte)))
|
|
return VM_FAULT_NOPAGE;
|
|
|
|
flush_icache_page(vma, page);
|
|
entry = mk_pte(page, vma->vm_page_prot);
|
|
if (write)
|
|
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
|
|
/* copy-on-write page */
|
|
if (write && !(vma->vm_flags & VM_SHARED)) {
|
|
inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
|
|
page_add_new_anon_rmap(page, vma, fe->address, false);
|
|
mem_cgroup_commit_charge(page, memcg, false, false);
|
|
lru_cache_add_active_or_unevictable(page, vma);
|
|
} else {
|
|
inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
|
|
page_add_file_rmap(page, false);
|
|
}
|
|
set_pte_at(vma->vm_mm, fe->address, fe->pte, entry);
|
|
|
|
/* no need to invalidate: a not-present page won't be cached */
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long fault_around_bytes __read_mostly =
|
|
rounddown_pow_of_two(65536);
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
static int fault_around_bytes_get(void *data, u64 *val)
|
|
{
|
|
*val = fault_around_bytes;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* fault_around_pages() and fault_around_mask() expects fault_around_bytes
|
|
* rounded down to nearest page order. It's what do_fault_around() expects to
|
|
* see.
|
|
*/
|
|
static int fault_around_bytes_set(void *data, u64 val)
|
|
{
|
|
if (val / PAGE_SIZE > PTRS_PER_PTE)
|
|
return -EINVAL;
|
|
if (val > PAGE_SIZE)
|
|
fault_around_bytes = rounddown_pow_of_two(val);
|
|
else
|
|
fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
|
|
return 0;
|
|
}
|
|
DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops,
|
|
fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
|
|
|
|
static int __init fault_around_debugfs(void)
|
|
{
|
|
void *ret;
|
|
|
|
ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL,
|
|
&fault_around_bytes_fops);
|
|
if (!ret)
|
|
pr_warn("Failed to create fault_around_bytes in debugfs");
|
|
return 0;
|
|
}
|
|
late_initcall(fault_around_debugfs);
|
|
#endif
|
|
|
|
/*
|
|
* do_fault_around() tries to map few pages around the fault address. The hope
|
|
* is that the pages will be needed soon and this will lower the number of
|
|
* faults to handle.
|
|
*
|
|
* It uses vm_ops->map_pages() to map the pages, which skips the page if it's
|
|
* not ready to be mapped: not up-to-date, locked, etc.
|
|
*
|
|
* This function is called with the page table lock taken. In the split ptlock
|
|
* case the page table lock only protects only those entries which belong to
|
|
* the page table corresponding to the fault address.
|
|
*
|
|
* This function doesn't cross the VMA boundaries, in order to call map_pages()
|
|
* only once.
|
|
*
|
|
* fault_around_pages() defines how many pages we'll try to map.
|
|
* do_fault_around() expects it to return a power of two less than or equal to
|
|
* PTRS_PER_PTE.
|
|
*
|
|
* The virtual address of the area that we map is naturally aligned to the
|
|
* fault_around_pages() value (and therefore to page order). This way it's
|
|
* easier to guarantee that we don't cross page table boundaries.
|
|
*/
|
|
static int do_fault_around(struct fault_env *fe, pgoff_t start_pgoff)
|
|
{
|
|
unsigned long address = fe->address, nr_pages, mask;
|
|
pgoff_t end_pgoff;
|
|
int off, ret = 0;
|
|
|
|
nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
|
|
mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
|
|
|
|
fe->address = max(address & mask, fe->vma->vm_start);
|
|
off = ((address - fe->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
|
|
start_pgoff -= off;
|
|
|
|
/*
|
|
* end_pgoff is either end of page table or end of vma
|
|
* or fault_around_pages() from start_pgoff, depending what is nearest.
|
|
*/
|
|
end_pgoff = start_pgoff -
|
|
((fe->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
|
|
PTRS_PER_PTE - 1;
|
|
end_pgoff = min3(end_pgoff, vma_pages(fe->vma) + fe->vma->vm_pgoff - 1,
|
|
start_pgoff + nr_pages - 1);
|
|
|
|
if (pmd_none(*fe->pmd)) {
|
|
fe->prealloc_pte = pte_alloc_one(fe->vma->vm_mm, fe->address);
|
|
if (!fe->prealloc_pte)
|
|
goto out;
|
|
smp_wmb(); /* See comment in __pte_alloc() */
|
|
}
|
|
|
|
fe->vma->vm_ops->map_pages(fe, start_pgoff, end_pgoff);
|
|
|
|
/* preallocated pagetable is unused: free it */
|
|
if (fe->prealloc_pte) {
|
|
pte_free(fe->vma->vm_mm, fe->prealloc_pte);
|
|
fe->prealloc_pte = 0;
|
|
}
|
|
/* Huge page is mapped? Page fault is solved */
|
|
if (pmd_trans_huge(*fe->pmd)) {
|
|
ret = VM_FAULT_NOPAGE;
|
|
goto out;
|
|
}
|
|
|
|
/* ->map_pages() haven't done anything useful. Cold page cache? */
|
|
if (!fe->pte)
|
|
goto out;
|
|
|
|
/* check if the page fault is solved */
|
|
fe->pte -= (fe->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
|
|
if (!pte_none(*fe->pte))
|
|
ret = VM_FAULT_NOPAGE;
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
out:
|
|
fe->address = address;
|
|
fe->pte = NULL;
|
|
return ret;
|
|
}
|
|
|
|
static int do_read_fault(struct fault_env *fe, pgoff_t pgoff)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *fault_page;
|
|
int ret = 0;
|
|
|
|
/*
|
|
* Let's call ->map_pages() first and use ->fault() as fallback
|
|
* if page by the offset is not ready to be mapped (cold cache or
|
|
* something).
|
|
*/
|
|
if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
|
|
ret = do_fault_around(fe, pgoff);
|
|
if (ret)
|
|
return ret;
|
|
}
|
|
|
|
ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
return ret;
|
|
|
|
ret |= alloc_set_pte(fe, NULL, fault_page);
|
|
if (fe->pte)
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
unlock_page(fault_page);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
put_page(fault_page);
|
|
return ret;
|
|
}
|
|
|
|
static int do_cow_fault(struct fault_env *fe, pgoff_t pgoff)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *fault_page, *new_page;
|
|
void *fault_entry;
|
|
struct mem_cgroup *memcg;
|
|
int ret;
|
|
|
|
if (unlikely(anon_vma_prepare(vma)))
|
|
return VM_FAULT_OOM;
|
|
|
|
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, fe->address);
|
|
if (!new_page)
|
|
return VM_FAULT_OOM;
|
|
|
|
if (mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL,
|
|
&memcg, false)) {
|
|
put_page(new_page);
|
|
return VM_FAULT_OOM;
|
|
}
|
|
|
|
ret = __do_fault(fe, pgoff, new_page, &fault_page, &fault_entry);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
goto uncharge_out;
|
|
|
|
if (!(ret & VM_FAULT_DAX_LOCKED))
|
|
copy_user_highpage(new_page, fault_page, fe->address, vma);
|
|
__SetPageUptodate(new_page);
|
|
|
|
ret |= alloc_set_pte(fe, memcg, new_page);
|
|
if (fe->pte)
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
if (!(ret & VM_FAULT_DAX_LOCKED)) {
|
|
unlock_page(fault_page);
|
|
put_page(fault_page);
|
|
} else {
|
|
dax_unlock_mapping_entry(vma->vm_file->f_mapping, pgoff);
|
|
}
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
goto uncharge_out;
|
|
return ret;
|
|
uncharge_out:
|
|
mem_cgroup_cancel_charge(new_page, memcg, false);
|
|
put_page(new_page);
|
|
return ret;
|
|
}
|
|
|
|
static int do_shared_fault(struct fault_env *fe, pgoff_t pgoff)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *fault_page;
|
|
struct address_space *mapping;
|
|
int dirtied = 0;
|
|
int ret, tmp;
|
|
|
|
ret = __do_fault(fe, pgoff, NULL, &fault_page, NULL);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
|
|
return ret;
|
|
|
|
/*
|
|
* Check if the backing address space wants to know that the page is
|
|
* about to become writable
|
|
*/
|
|
if (vma->vm_ops->page_mkwrite) {
|
|
unlock_page(fault_page);
|
|
tmp = do_page_mkwrite(vma, fault_page, fe->address);
|
|
if (unlikely(!tmp ||
|
|
(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
|
|
put_page(fault_page);
|
|
return tmp;
|
|
}
|
|
}
|
|
|
|
ret |= alloc_set_pte(fe, NULL, fault_page);
|
|
if (fe->pte)
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
|
|
VM_FAULT_RETRY))) {
|
|
unlock_page(fault_page);
|
|
put_page(fault_page);
|
|
return ret;
|
|
}
|
|
|
|
if (set_page_dirty(fault_page))
|
|
dirtied = 1;
|
|
/*
|
|
* Take a local copy of the address_space - page.mapping may be zeroed
|
|
* by truncate after unlock_page(). The address_space itself remains
|
|
* pinned by vma->vm_file's reference. We rely on unlock_page()'s
|
|
* release semantics to prevent the compiler from undoing this copying.
|
|
*/
|
|
mapping = page_rmapping(fault_page);
|
|
unlock_page(fault_page);
|
|
if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
|
|
/*
|
|
* Some device drivers do not set page.mapping but still
|
|
* dirty their pages
|
|
*/
|
|
balance_dirty_pages_ratelimited(mapping);
|
|
}
|
|
|
|
if (!vma->vm_ops->page_mkwrite)
|
|
file_update_time(vma->vm_file);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* We enter with non-exclusive mmap_sem (to exclude vma changes,
|
|
* but allow concurrent faults).
|
|
* The mmap_sem may have been released depending on flags and our
|
|
* return value. See filemap_fault() and __lock_page_or_retry().
|
|
*/
|
|
static int do_fault(struct fault_env *fe)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
pgoff_t pgoff = linear_page_index(vma, fe->address);
|
|
|
|
/* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
|
|
if (!vma->vm_ops->fault)
|
|
return VM_FAULT_SIGBUS;
|
|
if (!(fe->flags & FAULT_FLAG_WRITE))
|
|
return do_read_fault(fe, pgoff);
|
|
if (!(vma->vm_flags & VM_SHARED))
|
|
return do_cow_fault(fe, pgoff);
|
|
return do_shared_fault(fe, pgoff);
|
|
}
|
|
|
|
static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
|
|
unsigned long addr, int page_nid,
|
|
int *flags)
|
|
{
|
|
get_page(page);
|
|
|
|
count_vm_numa_event(NUMA_HINT_FAULTS);
|
|
if (page_nid == numa_node_id()) {
|
|
count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
|
|
*flags |= TNF_FAULT_LOCAL;
|
|
}
|
|
|
|
return mpol_misplaced(page, vma, addr);
|
|
}
|
|
|
|
static int do_numa_page(struct fault_env *fe, pte_t pte)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
struct page *page = NULL;
|
|
int page_nid = -1;
|
|
int last_cpupid;
|
|
int target_nid;
|
|
bool migrated = false;
|
|
bool was_writable = pte_write(pte);
|
|
int flags = 0;
|
|
|
|
/*
|
|
* The "pte" at this point cannot be used safely without
|
|
* validation through pte_unmap_same(). It's of NUMA type but
|
|
* the pfn may be screwed if the read is non atomic.
|
|
*
|
|
* We can safely just do a "set_pte_at()", because the old
|
|
* page table entry is not accessible, so there would be no
|
|
* concurrent hardware modifications to the PTE.
|
|
*/
|
|
fe->ptl = pte_lockptr(vma->vm_mm, fe->pmd);
|
|
spin_lock(fe->ptl);
|
|
if (unlikely(!pte_same(*fe->pte, pte))) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
goto out;
|
|
}
|
|
|
|
/* Make it present again */
|
|
pte = pte_modify(pte, vma->vm_page_prot);
|
|
pte = pte_mkyoung(pte);
|
|
if (was_writable)
|
|
pte = pte_mkwrite(pte);
|
|
set_pte_at(vma->vm_mm, fe->address, fe->pte, pte);
|
|
update_mmu_cache(vma, fe->address, fe->pte);
|
|
|
|
page = vm_normal_page(vma, fe->address, pte);
|
|
if (!page) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return 0;
|
|
}
|
|
|
|
/* TODO: handle PTE-mapped THP */
|
|
if (PageCompound(page)) {
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Avoid grouping on RO pages in general. RO pages shouldn't hurt as
|
|
* much anyway since they can be in shared cache state. This misses
|
|
* the case where a mapping is writable but the process never writes
|
|
* to it but pte_write gets cleared during protection updates and
|
|
* pte_dirty has unpredictable behaviour between PTE scan updates,
|
|
* background writeback, dirty balancing and application behaviour.
|
|
*/
|
|
if (!pte_write(pte))
|
|
flags |= TNF_NO_GROUP;
|
|
|
|
/*
|
|
* Flag if the page is shared between multiple address spaces. This
|
|
* is later used when determining whether to group tasks together
|
|
*/
|
|
if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
|
|
flags |= TNF_SHARED;
|
|
|
|
last_cpupid = page_cpupid_last(page);
|
|
page_nid = page_to_nid(page);
|
|
target_nid = numa_migrate_prep(page, vma, fe->address, page_nid,
|
|
&flags);
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
if (target_nid == -1) {
|
|
put_page(page);
|
|
goto out;
|
|
}
|
|
|
|
/* Migrate to the requested node */
|
|
migrated = migrate_misplaced_page(page, vma, target_nid);
|
|
if (migrated) {
|
|
page_nid = target_nid;
|
|
flags |= TNF_MIGRATED;
|
|
} else
|
|
flags |= TNF_MIGRATE_FAIL;
|
|
|
|
out:
|
|
if (page_nid != -1)
|
|
task_numa_fault(last_cpupid, page_nid, 1, flags);
|
|
return 0;
|
|
}
|
|
|
|
static int create_huge_pmd(struct fault_env *fe)
|
|
{
|
|
struct vm_area_struct *vma = fe->vma;
|
|
if (vma_is_anonymous(vma))
|
|
return do_huge_pmd_anonymous_page(fe);
|
|
if (vma->vm_ops->pmd_fault)
|
|
return vma->vm_ops->pmd_fault(vma, fe->address, fe->pmd,
|
|
fe->flags);
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd)
|
|
{
|
|
if (vma_is_anonymous(fe->vma))
|
|
return do_huge_pmd_wp_page(fe, orig_pmd);
|
|
if (fe->vma->vm_ops->pmd_fault)
|
|
return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd,
|
|
fe->flags);
|
|
|
|
/* COW handled on pte level: split pmd */
|
|
VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma);
|
|
split_huge_pmd(fe->vma, fe->pmd, fe->address);
|
|
|
|
return VM_FAULT_FALLBACK;
|
|
}
|
|
|
|
static inline bool vma_is_accessible(struct vm_area_struct *vma)
|
|
{
|
|
return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
|
|
}
|
|
|
|
/*
|
|
* These routines also need to handle stuff like marking pages dirty
|
|
* and/or accessed for architectures that don't do it in hardware (most
|
|
* RISC architectures). The early dirtying is also good on the i386.
|
|
*
|
|
* There is also a hook called "update_mmu_cache()" that architectures
|
|
* with external mmu caches can use to update those (ie the Sparc or
|
|
* PowerPC hashed page tables that act as extended TLBs).
|
|
*
|
|
* We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
|
|
* concurrent faults).
|
|
*
|
|
* The mmap_sem may have been released depending on flags and our return value.
|
|
* See filemap_fault() and __lock_page_or_retry().
|
|
*/
|
|
static int handle_pte_fault(struct fault_env *fe)
|
|
{
|
|
pte_t entry;
|
|
|
|
if (unlikely(pmd_none(*fe->pmd))) {
|
|
/*
|
|
* Leave __pte_alloc() until later: because vm_ops->fault may
|
|
* want to allocate huge page, and if we expose page table
|
|
* for an instant, it will be difficult to retract from
|
|
* concurrent faults and from rmap lookups.
|
|
*/
|
|
fe->pte = NULL;
|
|
} else {
|
|
/* See comment in pte_alloc_one_map() */
|
|
if (pmd_trans_unstable(fe->pmd) || pmd_devmap(*fe->pmd))
|
|
return 0;
|
|
/*
|
|
* A regular pmd is established and it can't morph into a huge
|
|
* pmd from under us anymore at this point because we hold the
|
|
* mmap_sem read mode and khugepaged takes it in write mode.
|
|
* So now it's safe to run pte_offset_map().
|
|
*/
|
|
fe->pte = pte_offset_map(fe->pmd, fe->address);
|
|
|
|
entry = *fe->pte;
|
|
|
|
/*
|
|
* some architectures can have larger ptes than wordsize,
|
|
* e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
|
|
* CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
|
|
* atomic accesses. The code below just needs a consistent
|
|
* view for the ifs and we later double check anyway with the
|
|
* ptl lock held. So here a barrier will do.
|
|
*/
|
|
barrier();
|
|
if (pte_none(entry)) {
|
|
pte_unmap(fe->pte);
|
|
fe->pte = NULL;
|
|
}
|
|
}
|
|
|
|
if (!fe->pte) {
|
|
if (vma_is_anonymous(fe->vma))
|
|
return do_anonymous_page(fe);
|
|
else
|
|
return do_fault(fe);
|
|
}
|
|
|
|
if (!pte_present(entry))
|
|
return do_swap_page(fe, entry);
|
|
|
|
if (pte_protnone(entry) && vma_is_accessible(fe->vma))
|
|
return do_numa_page(fe, entry);
|
|
|
|
fe->ptl = pte_lockptr(fe->vma->vm_mm, fe->pmd);
|
|
spin_lock(fe->ptl);
|
|
if (unlikely(!pte_same(*fe->pte, entry)))
|
|
goto unlock;
|
|
if (fe->flags & FAULT_FLAG_WRITE) {
|
|
if (!pte_write(entry))
|
|
return do_wp_page(fe, entry);
|
|
entry = pte_mkdirty(entry);
|
|
}
|
|
entry = pte_mkyoung(entry);
|
|
if (ptep_set_access_flags(fe->vma, fe->address, fe->pte, entry,
|
|
fe->flags & FAULT_FLAG_WRITE)) {
|
|
update_mmu_cache(fe->vma, fe->address, fe->pte);
|
|
} else {
|
|
/*
|
|
* This is needed only for protection faults but the arch code
|
|
* is not yet telling us if this is a protection fault or not.
|
|
* This still avoids useless tlb flushes for .text page faults
|
|
* with threads.
|
|
*/
|
|
if (fe->flags & FAULT_FLAG_WRITE)
|
|
flush_tlb_fix_spurious_fault(fe->vma, fe->address);
|
|
}
|
|
unlock:
|
|
pte_unmap_unlock(fe->pte, fe->ptl);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* By the time we get here, we already hold the mm semaphore
|
|
*
|
|
* The mmap_sem may have been released depending on flags and our
|
|
* return value. See filemap_fault() and __lock_page_or_retry().
|
|
*/
|
|
static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned int flags)
|
|
{
|
|
struct fault_env fe = {
|
|
.vma = vma,
|
|
.address = address,
|
|
.flags = flags,
|
|
};
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
pud = pud_alloc(mm, pgd, address);
|
|
if (!pud)
|
|
return VM_FAULT_OOM;
|
|
fe.pmd = pmd_alloc(mm, pud, address);
|
|
if (!fe.pmd)
|
|
return VM_FAULT_OOM;
|
|
if (pmd_none(*fe.pmd) && transparent_hugepage_enabled(vma)) {
|
|
int ret = create_huge_pmd(&fe);
|
|
if (!(ret & VM_FAULT_FALLBACK))
|
|
return ret;
|
|
} else {
|
|
pmd_t orig_pmd = *fe.pmd;
|
|
int ret;
|
|
|
|
barrier();
|
|
if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
|
|
if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
|
|
return do_huge_pmd_numa_page(&fe, orig_pmd);
|
|
|
|
if ((fe.flags & FAULT_FLAG_WRITE) &&
|
|
!pmd_write(orig_pmd)) {
|
|
ret = wp_huge_pmd(&fe, orig_pmd);
|
|
if (!(ret & VM_FAULT_FALLBACK))
|
|
return ret;
|
|
} else {
|
|
huge_pmd_set_accessed(&fe, orig_pmd);
|
|
return 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
return handle_pte_fault(&fe);
|
|
}
|
|
|
|
/*
|
|
* By the time we get here, we already hold the mm semaphore
|
|
*
|
|
* The mmap_sem may have been released depending on flags and our
|
|
* return value. See filemap_fault() and __lock_page_or_retry().
|
|
*/
|
|
int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned int flags)
|
|
{
|
|
int ret;
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
count_vm_event(PGFAULT);
|
|
mem_cgroup_count_vm_event(vma->vm_mm, PGFAULT);
|
|
|
|
/* do counter updates before entering really critical section. */
|
|
check_sync_rss_stat(current);
|
|
|
|
/*
|
|
* Enable the memcg OOM handling for faults triggered in user
|
|
* space. Kernel faults are handled more gracefully.
|
|
*/
|
|
if (flags & FAULT_FLAG_USER)
|
|
mem_cgroup_oom_enable();
|
|
|
|
if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
|
|
flags & FAULT_FLAG_INSTRUCTION,
|
|
flags & FAULT_FLAG_REMOTE))
|
|
return VM_FAULT_SIGSEGV;
|
|
|
|
if (unlikely(is_vm_hugetlb_page(vma)))
|
|
ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
|
|
else
|
|
ret = __handle_mm_fault(vma, address, flags);
|
|
|
|
if (flags & FAULT_FLAG_USER) {
|
|
mem_cgroup_oom_disable();
|
|
/*
|
|
* The task may have entered a memcg OOM situation but
|
|
* if the allocation error was handled gracefully (no
|
|
* VM_FAULT_OOM), there is no need to kill anything.
|
|
* Just clean up the OOM state peacefully.
|
|
*/
|
|
if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
|
|
mem_cgroup_oom_synchronize(false);
|
|
}
|
|
|
|
/*
|
|
* This mm has been already reaped by the oom reaper and so the
|
|
* refault cannot be trusted in general. Anonymous refaults would
|
|
* lose data and give a zero page instead e.g. This is especially
|
|
* problem for use_mm() because regular tasks will just die and
|
|
* the corrupted data will not be visible anywhere while kthread
|
|
* will outlive the oom victim and potentially propagate the date
|
|
* further.
|
|
*/
|
|
if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
|
|
&& test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
|
|
ret = VM_FAULT_SIGBUS;
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(handle_mm_fault);
|
|
|
|
#ifndef __PAGETABLE_PUD_FOLDED
|
|
/*
|
|
* Allocate page upper directory.
|
|
* We've already handled the fast-path in-line.
|
|
*/
|
|
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
|
|
{
|
|
pud_t *new = pud_alloc_one(mm, address);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
smp_wmb(); /* See comment in __pte_alloc */
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
if (pgd_present(*pgd)) /* Another has populated it */
|
|
pud_free(mm, new);
|
|
else
|
|
pgd_populate(mm, pgd, new);
|
|
spin_unlock(&mm->page_table_lock);
|
|
return 0;
|
|
}
|
|
#endif /* __PAGETABLE_PUD_FOLDED */
|
|
|
|
#ifndef __PAGETABLE_PMD_FOLDED
|
|
/*
|
|
* Allocate page middle directory.
|
|
* We've already handled the fast-path in-line.
|
|
*/
|
|
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
|
|
{
|
|
pmd_t *new = pmd_alloc_one(mm, address);
|
|
if (!new)
|
|
return -ENOMEM;
|
|
|
|
smp_wmb(); /* See comment in __pte_alloc */
|
|
|
|
spin_lock(&mm->page_table_lock);
|
|
#ifndef __ARCH_HAS_4LEVEL_HACK
|
|
if (!pud_present(*pud)) {
|
|
mm_inc_nr_pmds(mm);
|
|
pud_populate(mm, pud, new);
|
|
} else /* Another has populated it */
|
|
pmd_free(mm, new);
|
|
#else
|
|
if (!pgd_present(*pud)) {
|
|
mm_inc_nr_pmds(mm);
|
|
pgd_populate(mm, pud, new);
|
|
} else /* Another has populated it */
|
|
pmd_free(mm, new);
|
|
#endif /* __ARCH_HAS_4LEVEL_HACK */
|
|
spin_unlock(&mm->page_table_lock);
|
|
return 0;
|
|
}
|
|
#endif /* __PAGETABLE_PMD_FOLDED */
|
|
|
|
static int __follow_pte(struct mm_struct *mm, unsigned long address,
|
|
pte_t **ptepp, spinlock_t **ptlp)
|
|
{
|
|
pgd_t *pgd;
|
|
pud_t *pud;
|
|
pmd_t *pmd;
|
|
pte_t *ptep;
|
|
|
|
pgd = pgd_offset(mm, address);
|
|
if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
|
|
goto out;
|
|
|
|
pud = pud_offset(pgd, address);
|
|
if (pud_none(*pud) || unlikely(pud_bad(*pud)))
|
|
goto out;
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
VM_BUG_ON(pmd_trans_huge(*pmd));
|
|
if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
|
|
goto out;
|
|
|
|
/* We cannot handle huge page PFN maps. Luckily they don't exist. */
|
|
if (pmd_huge(*pmd))
|
|
goto out;
|
|
|
|
ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
|
|
if (!ptep)
|
|
goto out;
|
|
if (!pte_present(*ptep))
|
|
goto unlock;
|
|
*ptepp = ptep;
|
|
return 0;
|
|
unlock:
|
|
pte_unmap_unlock(ptep, *ptlp);
|
|
out:
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
|
|
pte_t **ptepp, spinlock_t **ptlp)
|
|
{
|
|
int res;
|
|
|
|
/* (void) is needed to make gcc happy */
|
|
(void) __cond_lock(*ptlp,
|
|
!(res = __follow_pte(mm, address, ptepp, ptlp)));
|
|
return res;
|
|
}
|
|
|
|
/**
|
|
* follow_pfn - look up PFN at a user virtual address
|
|
* @vma: memory mapping
|
|
* @address: user virtual address
|
|
* @pfn: location to store found PFN
|
|
*
|
|
* Only IO mappings and raw PFN mappings are allowed.
|
|
*
|
|
* Returns zero and the pfn at @pfn on success, -ve otherwise.
|
|
*/
|
|
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
|
|
unsigned long *pfn)
|
|
{
|
|
int ret = -EINVAL;
|
|
spinlock_t *ptl;
|
|
pte_t *ptep;
|
|
|
|
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
|
|
return ret;
|
|
|
|
ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
|
|
if (ret)
|
|
return ret;
|
|
*pfn = pte_pfn(*ptep);
|
|
pte_unmap_unlock(ptep, ptl);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(follow_pfn);
|
|
|
|
#ifdef CONFIG_HAVE_IOREMAP_PROT
|
|
int follow_phys(struct vm_area_struct *vma,
|
|
unsigned long address, unsigned int flags,
|
|
unsigned long *prot, resource_size_t *phys)
|
|
{
|
|
int ret = -EINVAL;
|
|
pte_t *ptep, pte;
|
|
spinlock_t *ptl;
|
|
|
|
if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
|
|
goto out;
|
|
|
|
if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
|
|
goto out;
|
|
pte = *ptep;
|
|
|
|
if ((flags & FOLL_WRITE) && !pte_write(pte))
|
|
goto unlock;
|
|
|
|
*prot = pgprot_val(pte_pgprot(pte));
|
|
*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
|
|
|
|
ret = 0;
|
|
unlock:
|
|
pte_unmap_unlock(ptep, ptl);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
|
|
void *buf, int len, int write)
|
|
{
|
|
resource_size_t phys_addr;
|
|
unsigned long prot = 0;
|
|
void __iomem *maddr;
|
|
int offset = addr & (PAGE_SIZE-1);
|
|
|
|
if (follow_phys(vma, addr, write, &prot, &phys_addr))
|
|
return -EINVAL;
|
|
|
|
maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
|
|
if (write)
|
|
memcpy_toio(maddr + offset, buf, len);
|
|
else
|
|
memcpy_fromio(buf, maddr + offset, len);
|
|
iounmap(maddr);
|
|
|
|
return len;
|
|
}
|
|
EXPORT_SYMBOL_GPL(generic_access_phys);
|
|
#endif
|
|
|
|
/*
|
|
* Access another process' address space as given in mm. If non-NULL, use the
|
|
* given task for page fault accounting.
|
|
*/
|
|
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
|
|
unsigned long addr, void *buf, int len, int write)
|
|
{
|
|
struct vm_area_struct *vma;
|
|
void *old_buf = buf;
|
|
|
|
down_read(&mm->mmap_sem);
|
|
/* ignore errors, just check how much was successfully transferred */
|
|
while (len) {
|
|
int bytes, ret, offset;
|
|
void *maddr;
|
|
struct page *page = NULL;
|
|
|
|
ret = get_user_pages_remote(tsk, mm, addr, 1,
|
|
write, 1, &page, &vma);
|
|
if (ret <= 0) {
|
|
#ifndef CONFIG_HAVE_IOREMAP_PROT
|
|
break;
|
|
#else
|
|
/*
|
|
* Check if this is a VM_IO | VM_PFNMAP VMA, which
|
|
* we can access using slightly different code.
|
|
*/
|
|
vma = find_vma(mm, addr);
|
|
if (!vma || vma->vm_start > addr)
|
|
break;
|
|
if (vma->vm_ops && vma->vm_ops->access)
|
|
ret = vma->vm_ops->access(vma, addr, buf,
|
|
len, write);
|
|
if (ret <= 0)
|
|
break;
|
|
bytes = ret;
|
|
#endif
|
|
} else {
|
|
bytes = len;
|
|
offset = addr & (PAGE_SIZE-1);
|
|
if (bytes > PAGE_SIZE-offset)
|
|
bytes = PAGE_SIZE-offset;
|
|
|
|
maddr = kmap(page);
|
|
if (write) {
|
|
copy_to_user_page(vma, page, addr,
|
|
maddr + offset, buf, bytes);
|
|
set_page_dirty_lock(page);
|
|
} else {
|
|
copy_from_user_page(vma, page, addr,
|
|
buf, maddr + offset, bytes);
|
|
}
|
|
kunmap(page);
|
|
put_page(page);
|
|
}
|
|
len -= bytes;
|
|
buf += bytes;
|
|
addr += bytes;
|
|
}
|
|
up_read(&mm->mmap_sem);
|
|
|
|
return buf - old_buf;
|
|
}
|
|
|
|
/**
|
|
* access_remote_vm - access another process' address space
|
|
* @mm: the mm_struct of the target address space
|
|
* @addr: start address to access
|
|
* @buf: source or destination buffer
|
|
* @len: number of bytes to transfer
|
|
* @write: whether the access is a write
|
|
*
|
|
* The caller must hold a reference on @mm.
|
|
*/
|
|
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
|
|
void *buf, int len, int write)
|
|
{
|
|
return __access_remote_vm(NULL, mm, addr, buf, len, write);
|
|
}
|
|
|
|
/*
|
|
* Access another process' address space.
|
|
* Source/target buffer must be kernel space,
|
|
* Do not walk the page table directly, use get_user_pages
|
|
*/
|
|
int access_process_vm(struct task_struct *tsk, unsigned long addr,
|
|
void *buf, int len, int write)
|
|
{
|
|
struct mm_struct *mm;
|
|
int ret;
|
|
|
|
mm = get_task_mm(tsk);
|
|
if (!mm)
|
|
return 0;
|
|
|
|
ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
|
|
mmput(mm);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* Print the name of a VMA.
|
|
*/
|
|
void print_vma_addr(char *prefix, unsigned long ip)
|
|
{
|
|
struct mm_struct *mm = current->mm;
|
|
struct vm_area_struct *vma;
|
|
|
|
/*
|
|
* Do not print if we are in atomic
|
|
* contexts (in exception stacks, etc.):
|
|
*/
|
|
if (preempt_count())
|
|
return;
|
|
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, ip);
|
|
if (vma && vma->vm_file) {
|
|
struct file *f = vma->vm_file;
|
|
char *buf = (char *)__get_free_page(GFP_KERNEL);
|
|
if (buf) {
|
|
char *p;
|
|
|
|
p = file_path(f, buf, PAGE_SIZE);
|
|
if (IS_ERR(p))
|
|
p = "?";
|
|
printk("%s%s[%lx+%lx]", prefix, kbasename(p),
|
|
vma->vm_start,
|
|
vma->vm_end - vma->vm_start);
|
|
free_page((unsigned long)buf);
|
|
}
|
|
}
|
|
up_read(&mm->mmap_sem);
|
|
}
|
|
|
|
#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
|
|
void __might_fault(const char *file, int line)
|
|
{
|
|
/*
|
|
* Some code (nfs/sunrpc) uses socket ops on kernel memory while
|
|
* holding the mmap_sem, this is safe because kernel memory doesn't
|
|
* get paged out, therefore we'll never actually fault, and the
|
|
* below annotations will generate false positives.
|
|
*/
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
|
return;
|
|
if (pagefault_disabled())
|
|
return;
|
|
__might_sleep(file, line, 0);
|
|
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
|
|
if (current->mm)
|
|
might_lock_read(¤t->mm->mmap_sem);
|
|
#endif
|
|
}
|
|
EXPORT_SYMBOL(__might_fault);
|
|
#endif
|
|
|
|
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
|
|
static void clear_gigantic_page(struct page *page,
|
|
unsigned long addr,
|
|
unsigned int pages_per_huge_page)
|
|
{
|
|
int i;
|
|
struct page *p = page;
|
|
|
|
might_sleep();
|
|
for (i = 0; i < pages_per_huge_page;
|
|
i++, p = mem_map_next(p, page, i)) {
|
|
cond_resched();
|
|
clear_user_highpage(p, addr + i * PAGE_SIZE);
|
|
}
|
|
}
|
|
void clear_huge_page(struct page *page,
|
|
unsigned long addr, unsigned int pages_per_huge_page)
|
|
{
|
|
int i;
|
|
|
|
if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
|
|
clear_gigantic_page(page, addr, pages_per_huge_page);
|
|
return;
|
|
}
|
|
|
|
might_sleep();
|
|
for (i = 0; i < pages_per_huge_page; i++) {
|
|
cond_resched();
|
|
clear_user_highpage(page + i, addr + i * PAGE_SIZE);
|
|
}
|
|
}
|
|
|
|
static void copy_user_gigantic_page(struct page *dst, struct page *src,
|
|
unsigned long addr,
|
|
struct vm_area_struct *vma,
|
|
unsigned int pages_per_huge_page)
|
|
{
|
|
int i;
|
|
struct page *dst_base = dst;
|
|
struct page *src_base = src;
|
|
|
|
for (i = 0; i < pages_per_huge_page; ) {
|
|
cond_resched();
|
|
copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
|
|
|
|
i++;
|
|
dst = mem_map_next(dst, dst_base, i);
|
|
src = mem_map_next(src, src_base, i);
|
|
}
|
|
}
|
|
|
|
void copy_user_huge_page(struct page *dst, struct page *src,
|
|
unsigned long addr, struct vm_area_struct *vma,
|
|
unsigned int pages_per_huge_page)
|
|
{
|
|
int i;
|
|
|
|
if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
|
|
copy_user_gigantic_page(dst, src, addr, vma,
|
|
pages_per_huge_page);
|
|
return;
|
|
}
|
|
|
|
might_sleep();
|
|
for (i = 0; i < pages_per_huge_page; i++) {
|
|
cond_resched();
|
|
copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
|
|
}
|
|
}
|
|
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
|
|
|
|
#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
|
|
|
|
static struct kmem_cache *page_ptl_cachep;
|
|
|
|
void __init ptlock_cache_init(void)
|
|
{
|
|
page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
|
|
SLAB_PANIC, NULL);
|
|
}
|
|
|
|
bool ptlock_alloc(struct page *page)
|
|
{
|
|
spinlock_t *ptl;
|
|
|
|
ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
|
|
if (!ptl)
|
|
return false;
|
|
page->ptl = ptl;
|
|
return true;
|
|
}
|
|
|
|
void ptlock_free(struct page *page)
|
|
{
|
|
kmem_cache_free(page_ptl_cachep, page->ptl);
|
|
}
|
|
#endif
|