mm: introduce memalloc_retry_wait()

Various places in the kernel - largely in filesystems - respond to a
memory allocation failure by looping around and re-trying.  Some of
these cannot conveniently use __GFP_NOFAIL, for reasons such as:

 - a GFP_ATOMIC allocation, which __GFP_NOFAIL doesn't work on
 - a need to check for the process being signalled between failures
 - the possibility that other recovery actions could be performed
 - the allocation is quite deep in support code, and passing down an
   extra flag to say if __GFP_NOFAIL is wanted would be clumsy.

Many of these currently use congestion_wait() which (in almost all
cases) simply waits the given timeout - congestion isn't tracked for
most devices.

It isn't clear what the best delay is for loops, but it is clear that
the various filesystems shouldn't be responsible for choosing a timeout.

This patch introduces memalloc_retry_wait() with takes on that
responsibility.  Code that wants to retry a memory allocation can call
this function passing the GFP flags that were used.  It will wait
however is appropriate.

For now, it only considers __GFP_NORETRY and whatever
gfpflags_allow_blocking() tests.  If blocking is allowed without
__GFP_NORETRY, then alloc_page either made some reclaim progress, or
waited for a while, before failing.  So there is no need for much
further waiting.  memalloc_retry_wait() will wait until the current
jiffie ends.  If this condition is not met, then alloc_page() won't have
waited much if at all.  In that case memalloc_retry_wait() waits about
200ms.  This is the delay that most current loops uses.

linux/sched/mm.h needs to be included in some files now,
but linux/backing-dev.h does not.

Link: https://lkml.kernel.org/r/163754371968.13692.1277530886009912421@noble.neil.brown.name
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Chao Yu <chao@kernel.org>
Cc: Darrick J. Wong <djwong@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
NeilBrown 2022-01-14 14:07:14 -08:00 коммит произвёл Linus Torvalds
Родитель 704687deaa
Коммит 4034247a0d
14 изменённых файлов: 56 добавлений и 37 удалений

Просмотреть файл

@ -27,8 +27,8 @@
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/fiemap.h>
#include <linux/backing-dev.h>
#include <linux/iomap.h>
#include <linux/sched/mm.h>
#include "ext4_jbd2.h"
#include "ext4_extents.h"
#include "xattr.h"
@ -4407,8 +4407,7 @@ retry:
err = ext4_es_remove_extent(inode, last_block,
EXT_MAX_BLOCKS - last_block);
if (err == -ENOMEM) {
cond_resched();
congestion_wait(BLK_RW_ASYNC, HZ/50);
memalloc_retry_wait(GFP_ATOMIC);
goto retry;
}
if (err)
@ -4416,8 +4415,7 @@ retry:
retry_remove_space:
err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
if (err == -ENOMEM) {
cond_resched();
congestion_wait(BLK_RW_ASYNC, HZ/50);
memalloc_retry_wait(GFP_ATOMIC);
goto retry_remove_space;
}
return err;

Просмотреть файл

@ -7,7 +7,7 @@
#include <linux/iomap.h>
#include <linux/fiemap.h>
#include <linux/iversion.h>
#include <linux/backing-dev.h>
#include <linux/sched/mm.h>
#include "ext4_jbd2.h"
#include "ext4.h"
@ -1929,8 +1929,7 @@ int ext4_inline_data_truncate(struct inode *inode, int *has_inline)
retry:
err = ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS);
if (err == -ENOMEM) {
cond_resched();
congestion_wait(BLK_RW_ASYNC, HZ/50);
memalloc_retry_wait(GFP_ATOMIC);
goto retry;
}
if (err)

Просмотреть файл

@ -24,7 +24,7 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/sched/mm.h>
#include "ext4_jbd2.h"
#include "xattr.h"
@ -523,12 +523,13 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
ret = PTR_ERR(bounce_page);
if (ret == -ENOMEM &&
(io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
gfp_flags = GFP_NOFS;
gfp_t new_gfp_flags = GFP_NOFS;
if (io->io_bio)
ext4_io_submit(io);
else
gfp_flags |= __GFP_NOFAIL;
congestion_wait(BLK_RW_ASYNC, HZ/50);
new_gfp_flags |= __GFP_NOFAIL;
memalloc_retry_wait(gfp_flags);
gfp_flags = new_gfp_flags;
goto retry_encrypt;
}

Просмотреть файл

@ -8,9 +8,9 @@
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/sched/mm.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/pagevec.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
@ -2542,7 +2542,7 @@ retry_encrypt:
/* flush pending IOs and wait for a while in the ENOMEM case */
if (PTR_ERR(fio->encrypted_page) == -ENOMEM) {
f2fs_flush_merged_writes(fio->sbi);
congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
gfp_flags |= __GFP_NOFAIL;
goto retry_encrypt;
}

Просмотреть файл

@ -7,7 +7,6 @@
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/backing-dev.h>
#include <linux/init.h>
#include <linux/f2fs_fs.h>
#include <linux/kthread.h>
@ -15,6 +14,7 @@
#include <linux/freezer.h>
#include <linux/sched/signal.h>
#include <linux/random.h>
#include <linux/sched/mm.h>
#include "f2fs.h"
#include "node.h"
@ -1375,8 +1375,7 @@ retry:
if (err) {
clear_page_private_gcing(page);
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto retry;
}
if (is_dirty)

Просмотреть файл

@ -8,8 +8,8 @@
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include <linux/writeback.h>
#include <linux/sched/mm.h>
#include "f2fs.h"
#include "node.h"
@ -562,7 +562,7 @@ retry:
inode = f2fs_iget(sb, ino);
if (IS_ERR(inode)) {
if (PTR_ERR(inode) == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto retry;
}
}

Просмотреть файл

@ -8,7 +8,7 @@
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/mpage.h>
#include <linux/backing-dev.h>
#include <linux/sched/mm.h>
#include <linux/blkdev.h>
#include <linux/pagevec.h>
#include <linux/swap.h>
@ -2750,7 +2750,7 @@ int f2fs_recover_inode_page(struct f2fs_sb_info *sbi, struct page *page)
retry:
ipage = f2fs_grab_cache_page(NODE_MAPPING(sbi), ino, false);
if (!ipage) {
congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto retry;
}

Просмотреть файл

@ -8,6 +8,7 @@
#include <asm/unaligned.h>
#include <linux/fs.h>
#include <linux/f2fs_fs.h>
#include <linux/sched/mm.h>
#include "f2fs.h"
#include "node.h"
#include "segment.h"
@ -587,7 +588,7 @@ retry_dn:
err = f2fs_get_dnode_of_data(&dn, start, ALLOC_NODE);
if (err) {
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto retry_dn;
}
goto out;
@ -670,8 +671,7 @@ retry_prev:
err = check_index_in_prev_nodes(sbi, dest, &dn);
if (err) {
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto retry_prev;
}
goto err;

Просмотреть файл

@ -9,6 +9,7 @@
#include <linux/f2fs_fs.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/sched/mm.h>
#include <linux/prefetch.h>
#include <linux/kthread.h>
#include <linux/swap.h>
@ -245,9 +246,7 @@ retry:
LOOKUP_NODE);
if (err) {
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
DEFAULT_IO_TIMEOUT);
cond_resched();
memalloc_retry_wait(GFP_NOFS);
goto retry;
}
err = -EAGAIN;
@ -424,9 +423,7 @@ retry:
err = f2fs_do_write_data_page(&fio);
if (err) {
if (err == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
DEFAULT_IO_TIMEOUT);
cond_resched();
memalloc_retry_wait(GFP_NOFS);
goto retry;
}
unlock_page(page);

Просмотреть файл

@ -8,9 +8,9 @@
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/sched/mm.h>
#include <linux/statfs.h>
#include <linux/buffer_head.h>
#include <linux/backing-dev.h>
#include <linux/kthread.h>
#include <linux/parser.h>
#include <linux/mount.h>
@ -2415,8 +2415,7 @@ repeat:
page = read_cache_page_gfp(mapping, blkidx, GFP_NOFS);
if (IS_ERR(page)) {
if (PTR_ERR(page) == -ENOMEM) {
congestion_wait(BLK_RW_ASYNC,
DEFAULT_IO_TIMEOUT);
memalloc_retry_wait(GFP_NOFS);
goto repeat;
}
set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);

Просмотреть файл

@ -4,7 +4,6 @@
* All Rights Reserved.
*/
#include "xfs.h"
#include <linux/backing-dev.h>
#include "xfs_message.h"
#include "xfs_trace.h"
@ -26,6 +25,6 @@ kmem_alloc(size_t size, xfs_km_flags_t flags)
"%s(%u) possible memory allocation deadlock size %u in %s (mode:0x%x)",
current->comm, current->pid,
(unsigned int)size, __func__, lflags);
congestion_wait(BLK_RW_ASYNC, HZ/50);
memalloc_retry_wait(lflags);
} while (1);
}

Просмотреть файл

@ -394,7 +394,7 @@ xfs_buf_alloc_pages(
}
XFS_STATS_INC(bp->b_mount, xb_page_retries);
congestion_wait(BLK_RW_ASYNC, HZ / 50);
memalloc_retry_wait(gfp_mask);
}
return 0;
}

Просмотреть файл

@ -214,6 +214,32 @@ static inline void fs_reclaim_acquire(gfp_t gfp_mask) { }
static inline void fs_reclaim_release(gfp_t gfp_mask) { }
#endif
/* Any memory-allocation retry loop should use
* memalloc_retry_wait(), and pass the flags for the most
* constrained allocation attempt that might have failed.
* This provides useful documentation of where loops are,
* and a central place to fine tune the waiting as the MM
* implementation changes.
*/
static inline void memalloc_retry_wait(gfp_t gfp_flags)
{
/* We use io_schedule_timeout because waiting for memory
* typically included waiting for dirty pages to be
* written out, which requires IO.
*/
__set_current_state(TASK_UNINTERRUPTIBLE);
gfp_flags = current_gfp_context(gfp_flags);
if (gfpflags_allow_blocking(gfp_flags) &&
!(gfp_flags & __GFP_NORETRY))
/* Probably waited already, no need for much more */
io_schedule_timeout(1);
else
/* Probably didn't wait, and has now released a lock,
* so now is a good time to wait
*/
io_schedule_timeout(HZ/50);
}
/**
* might_alloc - Mark possible allocation sites
* @gfp_mask: gfp_t flags that would be used to allocate

Просмотреть файл

@ -6,6 +6,7 @@
*/
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/errno.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
@ -688,7 +689,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
return -EINTR;
}
trace_svc_alloc_arg_err(pages);
schedule_timeout(msecs_to_jiffies(500));
memalloc_retry_wait(GFP_KERNEL);
}
rqstp->rq_page_end = &rqstp->rq_pages[pages];
rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */