Tetsuo Handa wrote: > 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(). Well, maybe we should not use memory reserves at all. I retested with this patch and kmallocwd patch applied. While depletion of memory reserves by wb_start_writeback() no longer occurs, I can still observe order-0 page allocation failure messages caused by GFP_ATOMIC allocation requests because wb_start_writeback() consumed memory reserves to the level where GFP_ATOMIC starts failing. Complete log is at http://I-love.SAKURA.ne.jp/tmp/serial-20160313.txt.xz . ---------- [ 89.794733] swapper/2: page allocation failure: order:0, mode:0x2200020(GFP_NOWAIT|__GFP_HIGH|__GFP_NOTRACK) [ 89.804714] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.5.0-rc7-next-20160311+ #399 [ 89.813049] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013 [ 89.819803] 0000000000000086 631ee38347526c6b ffff88007fc83640 ffffffff812b5c97 [ 89.823859] 0000000000000000 0000000000000000 ffff88007fc836d0 ffffffff811131b1 [ 89.827917] 02200020ffffffff 0000000000000040 fffffffffffffffe 0000000000000000 [ 89.831879] Call Trace: [ 89.834214] <IRQ> [<ffffffff812b5c97>] dump_stack+0x4f/0x68 [ 89.837652] [<ffffffff811131b1>] warn_alloc_failed+0x101/0x160 [ 89.841115] [<ffffffff81116521>] __alloc_pages_nodemask+0x481/0xd50 [ 89.844677] [<ffffffff8115b977>] alloc_pages_current+0x87/0x110 [ 89.848158] [<ffffffff81163fe0>] new_slab+0x540/0x550 [ 89.851355] [<ffffffff8116624d>] ___slab_alloc+0x46d/0x580 [ 89.854856] [<ffffffffa0317180>] ? __nf_ct_ext_add_length+0x1a0/0x1e0 [nf_conntrack] [ 89.858996] [<ffffffffa0310e2d>] ? __nf_conntrack_alloc.isra.35+0x5d/0x1b0 [nf_conntrack] [ 89.863170] [<ffffffff8116611f>] ? ___slab_alloc+0x33f/0x580 [ 89.866604] [<ffffffff8110ff20>] ? mempool_alloc_slab+0x10/0x20 [ 89.870141] [<ffffffff8110ff20>] ? mempool_alloc_slab+0x10/0x20 [ 89.873866] [<ffffffff8118435b>] __slab_alloc.isra.68+0x46/0x55 [ 89.877354] [<ffffffffa0317180>] ? __nf_ct_ext_add_length+0x1a0/0x1e0 [nf_conntrack] [ 89.881370] [<ffffffffa0317180>] ? __nf_ct_ext_add_length+0x1a0/0x1e0 [nf_conntrack] [ 89.885328] [<ffffffff81166666>] __kmalloc+0x146/0x190 [ 89.888559] [<ffffffffa0317180>] __nf_ct_ext_add_length+0x1a0/0x1e0 [nf_conntrack] [ 89.892538] [<ffffffffa0310ebb>] ? __nf_conntrack_alloc.isra.35+0xeb/0x1b0 [nf_conntrack] [ 89.896557] [<ffffffffa031150c>] nf_conntrack_in+0x56c/0x830 [nf_conntrack] [ 89.900166] [<ffffffffa0330327>] ipv4_conntrack_in+0x17/0x20 [nf_conntrack_ipv4] [ 89.903902] [<ffffffff81501848>] nf_iterate+0x58/0x70 [ 89.906570] [<ffffffff815018d6>] nf_hook_slow+0x76/0xd0 [ 89.908271] [<ffffffff8150b0a8>] ip_rcv+0x2f8/0x410 [ 89.909803] [<ffffffff8150a7f0>] ? ip_local_deliver_finish+0x1e0/0x1e0 [ 89.911516] [<ffffffff814cc9f4>] __netif_receive_skb_core+0x354/0x9b0 [ 89.913284] [<ffffffff8153c79f>] ? udp4_gro_receive+0x1ef/0x2a0 [ 89.914906] [<ffffffff81544bd2>] ? inet_gro_receive+0x92/0x230 [ 89.916542] [<ffffffff814cefe3>] __netif_receive_skb+0x13/0x60 [ 89.918099] [<ffffffff814cf0a6>] netif_receive_skb_internal+0x76/0xd0 [ 89.919710] [<ffffffff814cfae8>] napi_gro_receive+0x78/0xc0 [ 89.921399] [<ffffffffa0065e43>] e1000_clean_rx_irq+0x153/0x490 [e1000] [ 89.923038] [<ffffffffa0063ccf>] e1000_clean+0x25f/0x8b0 [e1000] [ 89.924601] [<ffffffff8107fb31>] ? check_preempt_curr+0x71/0x90 [ 89.926098] [<ffffffff814d0acb>] net_rx_action+0x14b/0x320 [ 89.927636] [<ffffffff81060cd1>] __do_softirq+0xd1/0x250 [ 89.929034] [<ffffffff810610d4>] irq_exit+0xe4/0x100 [ 89.930443] [<ffffffff8101b2bd>] do_IRQ+0x5d/0xf0 [ 89.931769] [<ffffffff815cc6c9>] common_interrupt+0x89/0x89 [ 89.933210] <EOI> [<ffffffff81022e0b>] ? default_idle+0xb/0x20 [ 89.935050] [<ffffffff8102340a>] arch_cpu_idle+0xa/0x10 [ 89.936480] [<ffffffff81098625>] default_idle_call+0x25/0x30 [ 89.938031] [<ffffffff81098845>] cpu_startup_entry+0x215/0x2a0 [ 89.939517] [<ffffffff8103924b>] start_secondary+0x14b/0x170 [ 89.941103] Mem-Info: [ 89.942132] active_anon:288561 inactive_anon:2093 isolated_anon:0 [ 89.942132] active_file:10819 inactive_file:114585 isolated_file:32 [ 89.942132] unevictable:0 dirty:113936 writeback:679 unstable:0 [ 89.942132] slab_reclaimable:5394 slab_unreclaimable:7802 [ 89.942132] mapped:10005 shmem:2159 pagetables:2415 bounce:0 [ 89.942132] free:2367 free_pcp:98 free_cma:0 [ 89.950633] Node 0 DMA free:6952kB min:44kB low:56kB high:68kB active_anon:5308kB inactive_anon:140kB active_file:548kB inactive_file:1452kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15988kB managed:15904kB mlocked:0kB dirty:1452kB writeback:0kB mapped:540kB shmem:148kB slab_reclaimable:84kB slab_unreclaimable:544kB kernel_stack:384kB pagetables:56kB unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:12224 all_unreclaimable? yes [ 89.960099] lowmem_reserve[]: 0 1732 1732 1732 [ 89.961626] Node 0 DMA32 free:2516kB min:5200kB low:6972kB high:8744kB active_anon:1148936kB inactive_anon:8232kB active_file:42728kB inactive_file:456888kB unevictable:0kB isolated(anon):0kB isolated(file):128kB present:2080640kB managed:1775252kB mlocked:0kB dirty:454292kB writeback:2716kB mapped:39480kB shmem:8488kB slab_reclaimable:21492kB slab_unreclaimable:30664kB kernel_stack:20960kB pagetables:9604kB unstable:0kB bounce:0kB free_pcp:392kB local_pcp:88kB free_cma:0kB writeback_tmp:0kB pages_scanned:7473108 all_unreclaimable? yes [ 89.972153] lowmem_reserve[]: 0 0 0 0 [ 89.973640] Node 0 DMA: 18*4kB (UM) 18*8kB (UE) 9*16kB (UE) 4*32kB (UE) 5*64kB (UME) 4*128kB (UME) 4*256kB (UE) 5*512kB (UME) 2*1024kB (UE) 0*2048kB 0*4096kB = 6952kB [ 89.978150] Node 0 DMA32: 281*4kB (UME) 172*8kB (UM) 1*16kB (E) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 2516kB [ 89.981301] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB [ 89.983498] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB [ 89.985688] 127595 total pagecache pages [ 89.987068] 0 pages in swap cache [ 89.988344] Swap cache stats: add 0, delete 0, find 0/0 [ 89.990303] Free swap = 0kB [ 89.991505] Total swap = 0kB [ 89.992755] 524157 pages RAM [ 89.993945] 0 pages HighMem/MovableOnly [ 89.995279] 76368 pages reserved [ 89.996633] 0 pages hwpoisoned [ 89.997845] SLUB: Unable to allocate memory on node -1, gfp=0x2088020(GFP_ATOMIC|__GFP_ZERO) [ 90.000147] cache: kmalloc-64, object size: 64, buffer size: 64, default order: 0, min order: 0 [ 90.002463] node 0: slabs: 728, objs: 46592, free: 0 [ 90.549072] swapper/2: page allocation failure: order:0, mode:0x2200020(GFP_NOWAIT|__GFP_HIGH|__GFP_NOTRACK) [ 90.559150] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.5.0-rc7-next-20160311+ #399 ---------- While no messages printed under OOM-livelock situation is annoying and page allocation failure messages by GFP_ATOMIC helps us to know we are under OOM-livelock situation, we will need to kill more processes if we allow wb_start_writeback() to consume half of memory reserves. wb_start_writeback() should not try to consume until min: watermark so that other GFP_NOIO allocations can succeed. But there is not such gfp flags. Anyway, please pick up below patch if you think GFP_NOWAIT is better than GFP_ATOMIC. ---------------------------------------- >From 5d43acbc5849a63494a732e39374692822145923 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Sun, 13 Mar 2016 23:03:05 +0900 Subject: [PATCH] mm,writeback: Don't use memory reserves for wb_start_writeback 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 allow wb_start_writeback() to use memory reserves. ---------- [ 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..21450c7 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_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); if (!work) { trace_writeback_nowork(wb); wb_wakeup(wb); -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
