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@ -0,0 +1,832 @@
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/*
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* Copyright (C) 2008, 2009 Intel Corporation
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* Authors: Andi Kleen, Fengguang Wu
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*
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* This software may be redistributed and/or modified under the terms of
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* the GNU General Public License ("GPL") version 2 only as published by the
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* Free Software Foundation.
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*
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* High level machine check handler. Handles pages reported by the
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* hardware as being corrupted usually due to a 2bit ECC memory or cache
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* failure.
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*
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* Handles page cache pages in various states. The tricky part
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* here is that we can access any page asynchronous to other VM
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* users, because memory failures could happen anytime and anywhere,
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* possibly violating some of their assumptions. This is why this code
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* has to be extremely careful. Generally it tries to use normal locking
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* rules, as in get the standard locks, even if that means the
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* error handling takes potentially a long time.
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*
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* The operation to map back from RMAP chains to processes has to walk
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* the complete process list and has non linear complexity with the number
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* mappings. In short it can be quite slow. But since memory corruptions
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* are rare we hope to get away with this.
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*/
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/*
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* Notebook:
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* - hugetlb needs more code
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* - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
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* - pass bad pages to kdump next kernel
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*/
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#define DEBUG 1 /* remove me in 2.6.34 */
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/page-flags.h>
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#include <linux/sched.h>
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#include <linux/rmap.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/backing-dev.h>
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#include "internal.h"
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int sysctl_memory_failure_early_kill __read_mostly = 0;
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int sysctl_memory_failure_recovery __read_mostly = 1;
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atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
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/*
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* Send all the processes who have the page mapped an ``action optional''
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* signal.
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*/
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static int kill_proc_ao(struct task_struct *t, unsigned long addr, int trapno,
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unsigned long pfn)
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{
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struct siginfo si;
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int ret;
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printk(KERN_ERR
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"MCE %#lx: Killing %s:%d early due to hardware memory corruption\n",
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pfn, t->comm, t->pid);
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si.si_signo = SIGBUS;
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si.si_errno = 0;
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si.si_code = BUS_MCEERR_AO;
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si.si_addr = (void *)addr;
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#ifdef __ARCH_SI_TRAPNO
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si.si_trapno = trapno;
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#endif
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si.si_addr_lsb = PAGE_SHIFT;
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/*
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* Don't use force here, it's convenient if the signal
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* can be temporarily blocked.
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* This could cause a loop when the user sets SIGBUS
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* to SIG_IGN, but hopefully noone will do that?
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*/
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ret = send_sig_info(SIGBUS, &si, t); /* synchronous? */
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if (ret < 0)
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printk(KERN_INFO "MCE: Error sending signal to %s:%d: %d\n",
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t->comm, t->pid, ret);
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return ret;
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}
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/*
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* Kill all processes that have a poisoned page mapped and then isolate
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* the page.
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*
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* General strategy:
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* Find all processes having the page mapped and kill them.
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* But we keep a page reference around so that the page is not
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* actually freed yet.
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* Then stash the page away
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*
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* There's no convenient way to get back to mapped processes
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* from the VMAs. So do a brute-force search over all
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* running processes.
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*
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* Remember that machine checks are not common (or rather
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* if they are common you have other problems), so this shouldn't
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* be a performance issue.
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*
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* Also there are some races possible while we get from the
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* error detection to actually handle it.
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*/
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struct to_kill {
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struct list_head nd;
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struct task_struct *tsk;
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unsigned long addr;
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unsigned addr_valid:1;
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};
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/*
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* Failure handling: if we can't find or can't kill a process there's
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* not much we can do. We just print a message and ignore otherwise.
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*/
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/*
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* Schedule a process for later kill.
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* Uses GFP_ATOMIC allocations to avoid potential recursions in the VM.
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* TBD would GFP_NOIO be enough?
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*/
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static void add_to_kill(struct task_struct *tsk, struct page *p,
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struct vm_area_struct *vma,
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struct list_head *to_kill,
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struct to_kill **tkc)
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{
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struct to_kill *tk;
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if (*tkc) {
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tk = *tkc;
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*tkc = NULL;
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} else {
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tk = kmalloc(sizeof(struct to_kill), GFP_ATOMIC);
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if (!tk) {
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printk(KERN_ERR
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"MCE: Out of memory while machine check handling\n");
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return;
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}
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}
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tk->addr = page_address_in_vma(p, vma);
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tk->addr_valid = 1;
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/*
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* In theory we don't have to kill when the page was
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* munmaped. But it could be also a mremap. Since that's
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* likely very rare kill anyways just out of paranoia, but use
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* a SIGKILL because the error is not contained anymore.
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*/
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if (tk->addr == -EFAULT) {
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pr_debug("MCE: Unable to find user space address %lx in %s\n",
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page_to_pfn(p), tsk->comm);
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tk->addr_valid = 0;
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}
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get_task_struct(tsk);
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tk->tsk = tsk;
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list_add_tail(&tk->nd, to_kill);
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}
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/*
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* Kill the processes that have been collected earlier.
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*
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* Only do anything when DOIT is set, otherwise just free the list
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* (this is used for clean pages which do not need killing)
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* Also when FAIL is set do a force kill because something went
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* wrong earlier.
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*/
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static void kill_procs_ao(struct list_head *to_kill, int doit, int trapno,
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int fail, unsigned long pfn)
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{
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struct to_kill *tk, *next;
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list_for_each_entry_safe (tk, next, to_kill, nd) {
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if (doit) {
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/*
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* In case something went wrong with munmaping
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* make sure the process doesn't catch the
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* signal and then access the memory. Just kill it.
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* the signal handlers
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*/
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if (fail || tk->addr_valid == 0) {
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printk(KERN_ERR
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"MCE %#lx: forcibly killing %s:%d because of failure to unmap corrupted page\n",
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pfn, tk->tsk->comm, tk->tsk->pid);
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force_sig(SIGKILL, tk->tsk);
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}
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/*
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* In theory the process could have mapped
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* something else on the address in-between. We could
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* check for that, but we need to tell the
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* process anyways.
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*/
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else if (kill_proc_ao(tk->tsk, tk->addr, trapno,
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pfn) < 0)
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printk(KERN_ERR
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"MCE %#lx: Cannot send advisory machine check signal to %s:%d\n",
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pfn, tk->tsk->comm, tk->tsk->pid);
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}
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put_task_struct(tk->tsk);
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kfree(tk);
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}
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}
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static int task_early_kill(struct task_struct *tsk)
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{
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if (!tsk->mm)
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return 0;
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if (tsk->flags & PF_MCE_PROCESS)
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return !!(tsk->flags & PF_MCE_EARLY);
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return sysctl_memory_failure_early_kill;
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}
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/*
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* Collect processes when the error hit an anonymous page.
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*/
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static void collect_procs_anon(struct page *page, struct list_head *to_kill,
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struct to_kill **tkc)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk;
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struct anon_vma *av;
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read_lock(&tasklist_lock);
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av = page_lock_anon_vma(page);
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if (av == NULL) /* Not actually mapped anymore */
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goto out;
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for_each_process (tsk) {
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if (!task_early_kill(tsk))
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continue;
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list_for_each_entry (vma, &av->head, anon_vma_node) {
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if (!page_mapped_in_vma(page, vma))
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continue;
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if (vma->vm_mm == tsk->mm)
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add_to_kill(tsk, page, vma, to_kill, tkc);
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}
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}
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page_unlock_anon_vma(av);
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out:
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read_unlock(&tasklist_lock);
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}
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/*
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* Collect processes when the error hit a file mapped page.
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*/
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static void collect_procs_file(struct page *page, struct list_head *to_kill,
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struct to_kill **tkc)
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{
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struct vm_area_struct *vma;
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struct task_struct *tsk;
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struct prio_tree_iter iter;
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struct address_space *mapping = page->mapping;
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/*
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* A note on the locking order between the two locks.
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* We don't rely on this particular order.
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* If you have some other code that needs a different order
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* feel free to switch them around. Or add a reverse link
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* from mm_struct to task_struct, then this could be all
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* done without taking tasklist_lock and looping over all tasks.
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*/
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read_lock(&tasklist_lock);
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spin_lock(&mapping->i_mmap_lock);
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for_each_process(tsk) {
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pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
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if (!task_early_kill(tsk))
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continue;
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vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff,
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pgoff) {
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/*
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* Send early kill signal to tasks where a vma covers
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* the page but the corrupted page is not necessarily
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* mapped it in its pte.
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* Assume applications who requested early kill want
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* to be informed of all such data corruptions.
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*/
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if (vma->vm_mm == tsk->mm)
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add_to_kill(tsk, page, vma, to_kill, tkc);
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}
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}
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spin_unlock(&mapping->i_mmap_lock);
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read_unlock(&tasklist_lock);
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}
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/*
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* Collect the processes who have the corrupted page mapped to kill.
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* This is done in two steps for locking reasons.
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* First preallocate one tokill structure outside the spin locks,
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* so that we can kill at least one process reasonably reliable.
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*/
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static void collect_procs(struct page *page, struct list_head *tokill)
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{
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struct to_kill *tk;
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if (!page->mapping)
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return;
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tk = kmalloc(sizeof(struct to_kill), GFP_NOIO);
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if (!tk)
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return;
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if (PageAnon(page))
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collect_procs_anon(page, tokill, &tk);
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else
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collect_procs_file(page, tokill, &tk);
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kfree(tk);
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}
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/*
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* Error handlers for various types of pages.
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*/
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enum outcome {
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FAILED, /* Error handling failed */
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DELAYED, /* Will be handled later */
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IGNORED, /* Error safely ignored */
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RECOVERED, /* Successfully recovered */
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};
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static const char *action_name[] = {
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[FAILED] = "Failed",
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[DELAYED] = "Delayed",
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[IGNORED] = "Ignored",
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[RECOVERED] = "Recovered",
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};
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/*
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* Error hit kernel page.
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|
|
|
* Do nothing, try to be lucky and not touch this instead. For a few cases we
|
|
|
|
|
* could be more sophisticated.
|
|
|
|
|
*/
|
|
|
|
|
static int me_kernel(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return DELAYED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Already poisoned page.
|
|
|
|
|
*/
|
|
|
|
|
static int me_ignore(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return IGNORED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Page in unknown state. Do nothing.
|
|
|
|
|
*/
|
|
|
|
|
static int me_unknown(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
printk(KERN_ERR "MCE %#lx: Unknown page state\n", pfn);
|
|
|
|
|
return FAILED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Free memory
|
|
|
|
|
*/
|
|
|
|
|
static int me_free(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return DELAYED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Clean (or cleaned) page cache page.
|
|
|
|
|
*/
|
|
|
|
|
static int me_pagecache_clean(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
int err;
|
|
|
|
|
int ret = FAILED;
|
|
|
|
|
struct address_space *mapping;
|
|
|
|
|
|
|
|
|
|
if (!isolate_lru_page(p))
|
|
|
|
|
page_cache_release(p);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* For anonymous pages we're done the only reference left
|
|
|
|
|
* should be the one m_f() holds.
|
|
|
|
|
*/
|
|
|
|
|
if (PageAnon(p))
|
|
|
|
|
return RECOVERED;
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Now truncate the page in the page cache. This is really
|
|
|
|
|
* more like a "temporary hole punch"
|
|
|
|
|
* Don't do this for block devices when someone else
|
|
|
|
|
* has a reference, because it could be file system metadata
|
|
|
|
|
* and that's not safe to truncate.
|
|
|
|
|
*/
|
|
|
|
|
mapping = page_mapping(p);
|
|
|
|
|
if (!mapping) {
|
|
|
|
|
/*
|
|
|
|
|
* Page has been teared down in the meanwhile
|
|
|
|
|
*/
|
|
|
|
|
return FAILED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Truncation is a bit tricky. Enable it per file system for now.
|
|
|
|
|
*
|
|
|
|
|
* Open: to take i_mutex or not for this? Right now we don't.
|
|
|
|
|
*/
|
|
|
|
|
if (mapping->a_ops->error_remove_page) {
|
|
|
|
|
err = mapping->a_ops->error_remove_page(mapping, p);
|
|
|
|
|
if (err != 0) {
|
|
|
|
|
printk(KERN_INFO "MCE %#lx: Failed to punch page: %d\n",
|
|
|
|
|
pfn, err);
|
|
|
|
|
} else if (page_has_private(p) &&
|
|
|
|
|
!try_to_release_page(p, GFP_NOIO)) {
|
|
|
|
|
pr_debug("MCE %#lx: failed to release buffers\n", pfn);
|
|
|
|
|
} else {
|
|
|
|
|
ret = RECOVERED;
|
|
|
|
|
}
|
|
|
|
|
} else {
|
|
|
|
|
/*
|
|
|
|
|
* If the file system doesn't support it just invalidate
|
|
|
|
|
* This fails on dirty or anything with private pages
|
|
|
|
|
*/
|
|
|
|
|
if (invalidate_inode_page(p))
|
|
|
|
|
ret = RECOVERED;
|
|
|
|
|
else
|
|
|
|
|
printk(KERN_INFO "MCE %#lx: Failed to invalidate\n",
|
|
|
|
|
pfn);
|
|
|
|
|
}
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Dirty cache page page
|
|
|
|
|
* Issues: when the error hit a hole page the error is not properly
|
|
|
|
|
* propagated.
|
|
|
|
|
*/
|
|
|
|
|
static int me_pagecache_dirty(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
struct address_space *mapping = page_mapping(p);
|
|
|
|
|
|
|
|
|
|
SetPageError(p);
|
|
|
|
|
/* TBD: print more information about the file. */
|
|
|
|
|
if (mapping) {
|
|
|
|
|
/*
|
|
|
|
|
* IO error will be reported by write(), fsync(), etc.
|
|
|
|
|
* who check the mapping.
|
|
|
|
|
* This way the application knows that something went
|
|
|
|
|
* wrong with its dirty file data.
|
|
|
|
|
*
|
|
|
|
|
* There's one open issue:
|
|
|
|
|
*
|
|
|
|
|
* The EIO will be only reported on the next IO
|
|
|
|
|
* operation and then cleared through the IO map.
|
|
|
|
|
* Normally Linux has two mechanisms to pass IO error
|
|
|
|
|
* first through the AS_EIO flag in the address space
|
|
|
|
|
* and then through the PageError flag in the page.
|
|
|
|
|
* Since we drop pages on memory failure handling the
|
|
|
|
|
* only mechanism open to use is through AS_AIO.
|
|
|
|
|
*
|
|
|
|
|
* This has the disadvantage that it gets cleared on
|
|
|
|
|
* the first operation that returns an error, while
|
|
|
|
|
* the PageError bit is more sticky and only cleared
|
|
|
|
|
* when the page is reread or dropped. If an
|
|
|
|
|
* application assumes it will always get error on
|
|
|
|
|
* fsync, but does other operations on the fd before
|
|
|
|
|
* and the page is dropped inbetween then the error
|
|
|
|
|
* will not be properly reported.
|
|
|
|
|
*
|
|
|
|
|
* This can already happen even without hwpoisoned
|
|
|
|
|
* pages: first on metadata IO errors (which only
|
|
|
|
|
* report through AS_EIO) or when the page is dropped
|
|
|
|
|
* at the wrong time.
|
|
|
|
|
*
|
|
|
|
|
* So right now we assume that the application DTRT on
|
|
|
|
|
* the first EIO, but we're not worse than other parts
|
|
|
|
|
* of the kernel.
|
|
|
|
|
*/
|
|
|
|
|
mapping_set_error(mapping, EIO);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return me_pagecache_clean(p, pfn);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Clean and dirty swap cache.
|
|
|
|
|
*
|
|
|
|
|
* Dirty swap cache page is tricky to handle. The page could live both in page
|
|
|
|
|
* cache and swap cache(ie. page is freshly swapped in). So it could be
|
|
|
|
|
* referenced concurrently by 2 types of PTEs:
|
|
|
|
|
* normal PTEs and swap PTEs. We try to handle them consistently by calling
|
|
|
|
|
* try_to_unmap(TTU_IGNORE_HWPOISON) to convert the normal PTEs to swap PTEs,
|
|
|
|
|
* and then
|
|
|
|
|
* - clear dirty bit to prevent IO
|
|
|
|
|
* - remove from LRU
|
|
|
|
|
* - but keep in the swap cache, so that when we return to it on
|
|
|
|
|
* a later page fault, we know the application is accessing
|
|
|
|
|
* corrupted data and shall be killed (we installed simple
|
|
|
|
|
* interception code in do_swap_page to catch it).
|
|
|
|
|
*
|
|
|
|
|
* Clean swap cache pages can be directly isolated. A later page fault will
|
|
|
|
|
* bring in the known good data from disk.
|
|
|
|
|
*/
|
|
|
|
|
static int me_swapcache_dirty(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
int ret = FAILED;
|
|
|
|
|
|
|
|
|
|
ClearPageDirty(p);
|
|
|
|
|
/* Trigger EIO in shmem: */
|
|
|
|
|
ClearPageUptodate(p);
|
|
|
|
|
|
|
|
|
|
if (!isolate_lru_page(p)) {
|
|
|
|
|
page_cache_release(p);
|
|
|
|
|
ret = DELAYED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static int me_swapcache_clean(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
int ret = FAILED;
|
|
|
|
|
|
|
|
|
|
if (!isolate_lru_page(p)) {
|
|
|
|
|
page_cache_release(p);
|
|
|
|
|
ret = RECOVERED;
|
|
|
|
|
}
|
|
|
|
|
delete_from_swap_cache(p);
|
|
|
|
|
return ret;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Huge pages. Needs work.
|
|
|
|
|
* Issues:
|
|
|
|
|
* No rmap support so we cannot find the original mapper. In theory could walk
|
|
|
|
|
* all MMs and look for the mappings, but that would be non atomic and racy.
|
|
|
|
|
* Need rmap for hugepages for this. Alternatively we could employ a heuristic,
|
|
|
|
|
* like just walking the current process and hoping it has it mapped (that
|
|
|
|
|
* should be usually true for the common "shared database cache" case)
|
|
|
|
|
* Should handle free huge pages and dequeue them too, but this needs to
|
|
|
|
|
* handle huge page accounting correctly.
|
|
|
|
|
*/
|
|
|
|
|
static int me_huge_page(struct page *p, unsigned long pfn)
|
|
|
|
|
{
|
|
|
|
|
return FAILED;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Various page states we can handle.
|
|
|
|
|
*
|
|
|
|
|
* A page state is defined by its current page->flags bits.
|
|
|
|
|
* The table matches them in order and calls the right handler.
|
|
|
|
|
*
|
|
|
|
|
* This is quite tricky because we can access page at any time
|
|
|
|
|
* in its live cycle, so all accesses have to be extremly careful.
|
|
|
|
|
*
|
|
|
|
|
* This is not complete. More states could be added.
|
|
|
|
|
* For any missing state don't attempt recovery.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#define dirty (1UL << PG_dirty)
|
|
|
|
|
#define sc (1UL << PG_swapcache)
|
|
|
|
|
#define unevict (1UL << PG_unevictable)
|
|
|
|
|
#define mlock (1UL << PG_mlocked)
|
|
|
|
|
#define writeback (1UL << PG_writeback)
|
|
|
|
|
#define lru (1UL << PG_lru)
|
|
|
|
|
#define swapbacked (1UL << PG_swapbacked)
|
|
|
|
|
#define head (1UL << PG_head)
|
|
|
|
|
#define tail (1UL << PG_tail)
|
|
|
|
|
#define compound (1UL << PG_compound)
|
|
|
|
|
#define slab (1UL << PG_slab)
|
|
|
|
|
#define buddy (1UL << PG_buddy)
|
|
|
|
|
#define reserved (1UL << PG_reserved)
|
|
|
|
|
|
|
|
|
|
static struct page_state {
|
|
|
|
|
unsigned long mask;
|
|
|
|
|
unsigned long res;
|
|
|
|
|
char *msg;
|
|
|
|
|
int (*action)(struct page *p, unsigned long pfn);
|
|
|
|
|
} error_states[] = {
|
|
|
|
|
{ reserved, reserved, "reserved kernel", me_ignore },
|
|
|
|
|
{ buddy, buddy, "free kernel", me_free },
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Could in theory check if slab page is free or if we can drop
|
|
|
|
|
* currently unused objects without touching them. But just
|
|
|
|
|
* treat it as standard kernel for now.
|
|
|
|
|
*/
|
|
|
|
|
{ slab, slab, "kernel slab", me_kernel },
|
|
|
|
|
|
|
|
|
|
#ifdef CONFIG_PAGEFLAGS_EXTENDED
|
|
|
|
|
{ head, head, "huge", me_huge_page },
|
|
|
|
|
{ tail, tail, "huge", me_huge_page },
|
|
|
|
|
#else
|
|
|
|
|
{ compound, compound, "huge", me_huge_page },
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
{ sc|dirty, sc|dirty, "swapcache", me_swapcache_dirty },
|
|
|
|
|
{ sc|dirty, sc, "swapcache", me_swapcache_clean },
|
|
|
|
|
|
|
|
|
|
{ unevict|dirty, unevict|dirty, "unevictable LRU", me_pagecache_dirty},
|
|
|
|
|
{ unevict, unevict, "unevictable LRU", me_pagecache_clean},
|
|
|
|
|
|
|
|
|
|
#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
|
|
|
|
|
{ mlock|dirty, mlock|dirty, "mlocked LRU", me_pagecache_dirty },
|
|
|
|
|
{ mlock, mlock, "mlocked LRU", me_pagecache_clean },
|
|
|
|
|
#endif
|
|
|
|
|
|
|
|
|
|
{ lru|dirty, lru|dirty, "LRU", me_pagecache_dirty },
|
|
|
|
|
{ lru|dirty, lru, "clean LRU", me_pagecache_clean },
|
|
|
|
|
{ swapbacked, swapbacked, "anonymous", me_pagecache_clean },
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Catchall entry: must be at end.
|
|
|
|
|
*/
|
|
|
|
|
{ 0, 0, "unknown page state", me_unknown },
|
|
|
|
|
};
|
|
|
|
|
|
|
|
|
|
#undef lru
|
|
|
|
|
|
|
|
|
|
static void action_result(unsigned long pfn, char *msg, int result)
|
|
|
|
|
{
|
|
|
|
|
struct page *page = NULL;
|
|
|
|
|
if (pfn_valid(pfn))
|
|
|
|
|
page = pfn_to_page(pfn);
|
|
|
|
|
|
|
|
|
|
printk(KERN_ERR "MCE %#lx: %s%s page recovery: %s\n",
|
|
|
|
|
pfn,
|
|
|
|
|
page && PageDirty(page) ? "dirty " : "",
|
|
|
|
|
msg, action_name[result]);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
static int page_action(struct page_state *ps, struct page *p,
|
|
|
|
|
unsigned long pfn, int ref)
|
|
|
|
|
{
|
|
|
|
|
int result;
|
|
|
|
|
|
|
|
|
|
result = ps->action(p, pfn);
|
|
|
|
|
action_result(pfn, ps->msg, result);
|
|
|
|
|
if (page_count(p) != 1 + ref)
|
|
|
|
|
printk(KERN_ERR
|
|
|
|
|
"MCE %#lx: %s page still referenced by %d users\n",
|
|
|
|
|
pfn, ps->msg, page_count(p) - 1);
|
|
|
|
|
|
|
|
|
|
/* Could do more checks here if page looks ok */
|
|
|
|
|
/*
|
|
|
|
|
* Could adjust zone counters here to correct for the missing page.
|
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
return result == RECOVERED ? 0 : -EBUSY;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
#define N_UNMAP_TRIES 5
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Do all that is necessary to remove user space mappings. Unmap
|
|
|
|
|
* the pages and send SIGBUS to the processes if the data was dirty.
|
|
|
|
|
*/
|
|
|
|
|
static void hwpoison_user_mappings(struct page *p, unsigned long pfn,
|
|
|
|
|
int trapno)
|
|
|
|
|
{
|
|
|
|
|
enum ttu_flags ttu = TTU_UNMAP | TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS;
|
|
|
|
|
struct address_space *mapping;
|
|
|
|
|
LIST_HEAD(tokill);
|
|
|
|
|
int ret;
|
|
|
|
|
int i;
|
|
|
|
|
int kill = 1;
|
|
|
|
|
|
|
|
|
|
if (PageReserved(p) || PageCompound(p) || PageSlab(p))
|
|
|
|
|
return;
|
|
|
|
|
|
|
|
|
|
if (!PageLRU(p))
|
|
|
|
|
lru_add_drain_all();
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* This check implies we don't kill processes if their pages
|
|
|
|
|
* are in the swap cache early. Those are always late kills.
|
|
|
|
|
*/
|
|
|
|
|
if (!page_mapped(p))
|
|
|
|
|
return;
|
|
|
|
|
|
|
|
|
|
if (PageSwapCache(p)) {
|
|
|
|
|
printk(KERN_ERR
|
|
|
|
|
"MCE %#lx: keeping poisoned page in swap cache\n", pfn);
|
|
|
|
|
ttu |= TTU_IGNORE_HWPOISON;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Propagate the dirty bit from PTEs to struct page first, because we
|
|
|
|
|
* need this to decide if we should kill or just drop the page.
|
|
|
|
|
*/
|
|
|
|
|
mapping = page_mapping(p);
|
|
|
|
|
if (!PageDirty(p) && mapping && mapping_cap_writeback_dirty(mapping)) {
|
|
|
|
|
if (page_mkclean(p)) {
|
|
|
|
|
SetPageDirty(p);
|
|
|
|
|
} else {
|
|
|
|
|
kill = 0;
|
|
|
|
|
ttu |= TTU_IGNORE_HWPOISON;
|
|
|
|
|
printk(KERN_INFO
|
|
|
|
|
"MCE %#lx: corrupted page was clean: dropped without side effects\n",
|
|
|
|
|
pfn);
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* First collect all the processes that have the page
|
|
|
|
|
* mapped in dirty form. This has to be done before try_to_unmap,
|
|
|
|
|
* because ttu takes the rmap data structures down.
|
|
|
|
|
*
|
|
|
|
|
* Error handling: We ignore errors here because
|
|
|
|
|
* there's nothing that can be done.
|
|
|
|
|
*/
|
|
|
|
|
if (kill)
|
|
|
|
|
collect_procs(p, &tokill);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* try_to_unmap can fail temporarily due to races.
|
|
|
|
|
* Try a few times (RED-PEN better strategy?)
|
|
|
|
|
*/
|
|
|
|
|
for (i = 0; i < N_UNMAP_TRIES; i++) {
|
|
|
|
|
ret = try_to_unmap(p, ttu);
|
|
|
|
|
if (ret == SWAP_SUCCESS)
|
|
|
|
|
break;
|
|
|
|
|
pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn, ret);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (ret != SWAP_SUCCESS)
|
|
|
|
|
printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
|
|
|
|
|
pfn, page_mapcount(p));
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Now that the dirty bit has been propagated to the
|
|
|
|
|
* struct page and all unmaps done we can decide if
|
|
|
|
|
* killing is needed or not. Only kill when the page
|
|
|
|
|
* was dirty, otherwise the tokill list is merely
|
|
|
|
|
* freed. When there was a problem unmapping earlier
|
|
|
|
|
* use a more force-full uncatchable kill to prevent
|
|
|
|
|
* any accesses to the poisoned memory.
|
|
|
|
|
*/
|
|
|
|
|
kill_procs_ao(&tokill, !!PageDirty(p), trapno,
|
|
|
|
|
ret != SWAP_SUCCESS, pfn);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
int __memory_failure(unsigned long pfn, int trapno, int ref)
|
|
|
|
|
{
|
|
|
|
|
struct page_state *ps;
|
|
|
|
|
struct page *p;
|
|
|
|
|
int res;
|
|
|
|
|
|
|
|
|
|
if (!sysctl_memory_failure_recovery)
|
|
|
|
|
panic("Memory failure from trap %d on page %lx", trapno, pfn);
|
|
|
|
|
|
|
|
|
|
if (!pfn_valid(pfn)) {
|
|
|
|
|
action_result(pfn, "memory outside kernel control", IGNORED);
|
|
|
|
|
return -EIO;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
p = pfn_to_page(pfn);
|
|
|
|
|
if (TestSetPageHWPoison(p)) {
|
|
|
|
|
action_result(pfn, "already hardware poisoned", IGNORED);
|
|
|
|
|
return 0;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
atomic_long_add(1, &mce_bad_pages);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* We need/can do nothing about count=0 pages.
|
|
|
|
|
* 1) it's a free page, and therefore in safe hand:
|
|
|
|
|
* prep_new_page() will be the gate keeper.
|
|
|
|
|
* 2) it's part of a non-compound high order page.
|
|
|
|
|
* Implies some kernel user: cannot stop them from
|
|
|
|
|
* R/W the page; let's pray that the page has been
|
|
|
|
|
* used and will be freed some time later.
|
|
|
|
|
* In fact it's dangerous to directly bump up page count from 0,
|
|
|
|
|
* that may make page_freeze_refs()/page_unfreeze_refs() mismatch.
|
|
|
|
|
*/
|
|
|
|
|
if (!get_page_unless_zero(compound_head(p))) {
|
|
|
|
|
action_result(pfn, "free or high order kernel", IGNORED);
|
|
|
|
|
return PageBuddy(compound_head(p)) ? 0 : -EBUSY;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Lock the page and wait for writeback to finish.
|
|
|
|
|
* It's very difficult to mess with pages currently under IO
|
|
|
|
|
* and in many cases impossible, so we just avoid it here.
|
|
|
|
|
*/
|
|
|
|
|
lock_page_nosync(p);
|
|
|
|
|
wait_on_page_writeback(p);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Now take care of user space mappings.
|
|
|
|
|
*/
|
|
|
|
|
hwpoison_user_mappings(p, pfn, trapno);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Torn down by someone else?
|
|
|
|
|
*/
|
|
|
|
|
if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
|
|
|
|
|
action_result(pfn, "already truncated LRU", IGNORED);
|
|
|
|
|
res = 0;
|
|
|
|
|
goto out;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
res = -EBUSY;
|
|
|
|
|
for (ps = error_states;; ps++) {
|
|
|
|
|
if ((p->flags & ps->mask) == ps->res) {
|
|
|
|
|
res = page_action(ps, p, pfn, ref);
|
|
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
out:
|
|
|
|
|
unlock_page(p);
|
|
|
|
|
return res;
|
|
|
|
|
}
|
|
|
|
|
EXPORT_SYMBOL_GPL(__memory_failure);
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
* memory_failure - Handle memory failure of a page.
|
|
|
|
|
* @pfn: Page Number of the corrupted page
|
|
|
|
|
* @trapno: Trap number reported in the signal to user space.
|
|
|
|
|
*
|
|
|
|
|
* This function is called by the low level machine check code
|
|
|
|
|
* of an architecture when it detects hardware memory corruption
|
|
|
|
|
* of a page. It tries its best to recover, which includes
|
|
|
|
|
* dropping pages, killing processes etc.
|
|
|
|
|
*
|
|
|
|
|
* The function is primarily of use for corruptions that
|
|
|
|
|
* happen outside the current execution context (e.g. when
|
|
|
|
|
* detected by a background scrubber)
|
|
|
|
|
*
|
|
|
|
|
* Must run in process context (e.g. a work queue) with interrupts
|
|
|
|
|
* enabled and no spinlocks hold.
|
|
|
|
|
*/
|
|
|
|
|
void memory_failure(unsigned long pfn, int trapno)
|
|
|
|
|
{
|
|
|
|
|
__memory_failure(pfn, trapno, 0);
|
|
|
|
|
}
|
Andi Kleen
Andi Kleen