When writeback operation cannot make forward progress because memory
allocation requests needed for doing I/O cannot be satisfied (e.g.
under OOM-livelock situation), we can observe flood of order-0 page
allocation failure messages caused by complete depletion of memory
reserves.
This is caused by unconditionally allocating "struct wb_writeback_work"
objects using GFP_ATOMIC from PF_MEMALLOC context.
__alloc_pages_nodemask() {
__alloc_pages_slowpath() {
__alloc_pages_direct_reclaim() {
__perform_reclaim() {
current->flags |= PF_MEMALLOC;
try_to_free_pages() {
do_try_to_free_pages() {
wakeup_flusher_threads() {
wb_start_writeback() {
kzalloc(sizeof(*work), GFP_ATOMIC) {
/* ALLOC_NO_WATERMARKS via PF_MEMALLOC */
}
}
}
}
}
current->flags &= ~PF_MEMALLOC;
}
}
}
}
Since I/O is stalling, allocating writeback requests forever shall deplete
memory reserves. Fortunately, since wb_start_writeback() can fall back to
wb_wakeup() when allocating "struct wb_writeback_work" failed, we don't
need to use ALLOC_NO_WATERMARKS for wb_start_writeback().
----------
[ 59.562581] Mem-Info:
[ 59.563935] active_anon:289393 inactive_anon:2093 isolated_anon:29
[ 59.563935] active_file:10838 inactive_file:113013 isolated_file:859
[ 59.563935] unevictable:0 dirty:108531 writeback:5308 unstable:0
[ 59.563935] slab_reclaimable:5526 slab_unreclaimable:7077
[ 59.563935] mapped:9970 shmem:2159 pagetables:2387 bounce:0
[ 59.563935] free:3042 free_pcp:0 free_cma:0
[ 59.574558] Node 0 DMA free:6968kB min:44kB low:52kB high:64kB active_anon:6056kB inactive_anon:176kB active_file:712kB inactive_file:744kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15988kB managed:15904kB mlocked:0kB dirty:756kB writeback:0kB mapped:736kB shmem:184kB slab_reclaimable:48kB slab_unreclaimable:208kB kernel_stack:160kB pagetables:144kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:9708 all_unreclaimable? yes
[ 59.585464] lowmem_reserve[]: 0 1732 1732 1732
[ 59.587123] Node 0 DMA32 free:5200kB min:5200kB low:6500kB high:7800kB active_anon:1151516kB inactive_anon:8196kB active_file:42640kB inactive_file:451076kB unevictable:0kB isolated(anon):116kB isolated(file):3564kB present:2080640kB managed:1775332kB mlocked:0kB dirty:433368kB writeback:21232kB mapped:39144kB shmem:8452kB slab_reclaimable:22056kB slab_unreclaimable:28100kB kernel_stack:20976kB pagetables:9404kB unstable:0kB bounce:0kB free_pcp:120kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:2701604 all_unreclaimable? no
[ 59.599649] lowmem_reserve[]: 0 0 0 0
[ 59.601431] Node 0 DMA: 25*4kB (UME) 16*8kB (UME) 3*16kB (UE) 5*32kB (UME) 2*64kB (UM) 2*128kB (ME) 2*256kB (ME) 1*512kB (E) 1*1024kB (E) 2*2048kB (ME) 0*4096kB = 6964kB
[ 59.606509] Node 0 DMA32: 925*4kB (UME) 140*8kB (UME) 5*16kB (ME) 5*32kB (M) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 5060kB
[ 59.610415] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
[ 59.612879] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[ 59.615308] 126847 total pagecache pages
[ 59.616921] 0 pages in swap cache
[ 59.618475] Swap cache stats: add 0, delete 0, find 0/0
[ 59.620268] Free swap = 0kB
[ 59.621650] Total swap = 0kB
[ 59.623011] 524157 pages RAM
[ 59.624365] 0 pages HighMem/MovableOnly
[ 59.625893] 76348 pages reserved
[ 59.627506] 0 pages hwpoisoned
[ 59.628838] Out of memory: Kill process 4450 (file_io.00) score 998 or sacrifice child
[ 59.631071] Killed process 4450 (file_io.00) total-vm:4308kB, anon-rss:100kB, file-rss:1184kB, shmem-rss:0kB
[ 61.526353] kthreadd: page allocation failure: order:0, mode:0x2200020
[ 61.527976] file_io.00: page allocation failure: order:0, mode:0x2200020
[ 61.527978] CPU: 0 PID: 4457 Comm: file_io.00 Not tainted 4.5.0-rc7+ #45
[ 61.527979] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
[ 61.527981] 0000000000000086 000000000005bb2d ffff88006cc5b588 ffffffff812a4d65
[ 61.527982] 0000000002200020 0000000000000000 ffff88006cc5b618 ffffffff81106dc7
[ 61.527983] 0000000000000000 ffffffffffffffff 00ff880000000000 ffff880000000004
[ 61.527983] Call Trace:
[ 61.528009] [<ffffffff812a4d65>] dump_stack+0x4d/0x68
[ 61.528012] [<ffffffff81106dc7>] warn_alloc_failed+0xf7/0x150
[ 61.528014] [<ffffffff81109e3f>] __alloc_pages_nodemask+0x23f/0xa60
[ 61.528016] [<ffffffff81137770>] ? page_check_address_transhuge+0x350/0x350
[ 61.528018] [<ffffffff8111327d>] ? page_evictable+0xd/0x40
[ 61.528019] [<ffffffff8114d927>] alloc_pages_current+0x87/0x110
[ 61.528021] [<ffffffff81155181>] new_slab+0x3a1/0x440
[ 61.528023] [<ffffffff81156fdf>] ___slab_alloc+0x3cf/0x590
[ 61.528024] [<ffffffff811a0999>] ? wb_start_writeback+0x39/0x90
[ 61.528027] [<ffffffff815a7f68>] ? preempt_schedule_common+0x1f/0x37
[ 61.528028] [<ffffffff815a7f9f>] ? preempt_schedule+0x1f/0x30
[ 61.528030] [<ffffffff81001012>] ? ___preempt_schedule+0x12/0x14
[ 61.528030] [<ffffffff811a0999>] ? wb_start_writeback+0x39/0x90
[ 61.528032] [<ffffffff81175536>] __slab_alloc.isra.64+0x18/0x1d
[ 61.528033] [<ffffffff8115778c>] kmem_cache_alloc+0x11c/0x150
[ 61.528034] [<ffffffff811a0999>] wb_start_writeback+0x39/0x90
[ 61.528035] [<ffffffff811a0d9f>] wakeup_flusher_threads+0x7f/0xf0
[ 61.528036] [<ffffffff81115ac9>] do_try_to_free_pages+0x1f9/0x410
[ 61.528037] [<ffffffff81115d74>] try_to_free_pages+0x94/0xc0
[ 61.528038] [<ffffffff8110a166>] __alloc_pages_nodemask+0x566/0xa60
[ 61.528040] [<ffffffff81200878>] ? xfs_bmapi_read+0x208/0x2f0
[ 61.528041] [<ffffffff8114d927>] alloc_pages_current+0x87/0x110
[ 61.528042] [<ffffffff8110092f>] __page_cache_alloc+0xaf/0xc0
[ 61.528043] [<ffffffff811011e8>] pagecache_get_page+0x88/0x260
[ 61.528044] [<ffffffff81101d31>] grab_cache_page_write_begin+0x21/0x40
[ 61.528046] [<ffffffff81222c9f>] xfs_vm_write_begin+0x2f/0xf0
[ 61.528047] [<ffffffff810b14be>] ? current_fs_time+0x1e/0x30
[ 61.528048] [<ffffffff81101eca>] generic_perform_write+0xca/0x1c0
[ 61.528050] [<ffffffff8107c390>] ? wake_up_process+0x10/0x20
[ 61.528051] [<ffffffff8122e01c>] xfs_file_buffered_aio_write+0xcc/0x1f0
[ 61.528052] [<ffffffff81079037>] ? finish_task_switch+0x77/0x280
[ 61.528053] [<ffffffff8122e1c4>] xfs_file_write_iter+0x84/0x140
[ 61.528054] [<ffffffff811777a7>] __vfs_write+0xc7/0x100
[ 61.528055] [<ffffffff811784cd>] vfs_write+0x9d/0x190
[ 61.528056] [<ffffffff810010a1>] ? do_audit_syscall_entry+0x61/0x70
[ 61.528057] [<ffffffff811793c0>] SyS_write+0x50/0xc0
[ 61.528059] [<ffffffff815ab4d7>] entry_SYSCALL_64_fastpath+0x12/0x6a
[ 61.528059] Mem-Info:
[ 61.528062] active_anon:293335 inactive_anon:2093 isolated_anon:0
[ 61.528062] active_file:10829 inactive_file:110045 isolated_file:32
[ 61.528062] unevictable:0 dirty:109275 writeback:822 unstable:0
[ 61.528062] slab_reclaimable:5489 slab_unreclaimable:10070
[ 61.528062] mapped:9999 shmem:2159 pagetables:2420 bounce:0
[ 61.528062] free:3 free_pcp:0 free_cma:0
[ 61.528065] Node 0 DMA free:12kB min:44kB low:52kB high:64kB active_anon:6060kB inactive_anon:176kB active_file:708kB inactive_file:756kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15988kB managed:15904kB mlocked:0kB dirty:756kB writeback:0kB mapped:736kB shmem:184kB slab_reclaimable:48kB slab_unreclaimable:7160kB kernel_stack:160kB pagetables:144kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:9844 all_unreclaimable? yes
[ 61.528066] lowmem_reserve[]: 0 1732 1732 1732
[ 61.528068] Node 0 DMA32 free:0kB min:5200kB low:6500kB high:7800kB active_anon:1167280kB inactive_anon:8196kB active_file:42608kB inactive_file:439424kB unevictable:0kB isolated(anon):0kB isolated(file):128kB present:2080640kB managed:1775332kB mlocked:0kB dirty:436344kB writeback:3288kB mapped:39260kB shmem:8452kB slab_reclaimable:21908kB slab_unreclaimable:33120kB kernel_stack:20976kB pagetables:9536kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:11073180 all_unreclaimable? yes
[ 61.528069] lowmem_reserve[]: 0 0 0 0
[ 61.528072] Node 0 DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
[ 61.528074] Node 0 DMA32: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
[ 61.528075] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
[ 61.528075] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
[ 61.528076] 123086 total pagecache pages
[ 61.528076] 0 pages in swap cache
[ 61.528077] Swap cache stats: add 0, delete 0, find 0/0
[ 61.528077] Free swap = 0kB
[ 61.528077] Total swap = 0kB
[ 61.528077] 524157 pages RAM
[ 61.528078] 0 pages HighMem/MovableOnly
[ 61.528078] 76348 pages reserved
[ 61.528078] 0 pages hwpoisoned
[ 61.528079] SLUB: Unable to allocate memory on node -1 (gfp=0x2088020)
[ 61.528080] cache: kmalloc-64, object size: 64, buffer size: 64, default order: 0, min order: 0
[ 61.528080] node 0: slabs: 3218, objs: 205952, free: 0
[ 61.528085] file_io.00: page allocation failure: order:0, mode:0x2200020
[ 61.528086] CPU: 0 PID: 4457 Comm: file_io.00 Not tainted 4.5.0-rc7+ #45
----------
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 5c46ed9..d4e13ec 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -929,7 +929,8 @@ void wb_start_writeback(struct bdi_writeback *wb, long nr_pages,
* This is WB_SYNC_NONE writeback, so if allocation fails just
* wakeup the thread for old dirty data writeback
*/
- work = kzalloc(sizeof(*work), GFP_ATOMIC);
+ work = kzalloc(sizeof(*work),
+ GFP_ATOMIC | __GFP_NOMEMALLOC | __GFP_NOWARN);
if (!work) {
trace_writeback_nowork(wb);
wb_wakeup(wb);
--
1.8.3.1
--
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