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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 committed by Linus Torvalds
parent 704687deaa
commit 4034247a0d
14 changed files with 56 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/ext4/extents.c
View File

@ -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;

5
fs/ext4/inline.c
View File

@ -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)

9
fs/ext4/page-io.c
View File

@ -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;
}

4
fs/f2fs/data.c
View File

@ -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;
}

5
fs/f2fs/gc.c
View File

@ -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)

4
fs/f2fs/inode.c
View File

@ -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;
}
}

4
fs/f2fs/node.c
View File

@ -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;
}

6
fs/f2fs/recovery.c
View File

@ -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;

9
fs/f2fs/segment.c
View File

@ -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);

5
fs/f2fs/super.c
View File

@ -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);

3
fs/xfs/kmem.c
View File

@ -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);
}

2
fs/xfs/xfs_buf.c
View File

@ -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;
}

26
include/linux/sched/mm.h
View File

@ -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

3
net/sunrpc/svc_xprt.c
View File

@ -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() */