On Thu, May 11, 2017 at 08:00:32AM +0900, Minchan Kim wrote: > Although there are a ton of free swap and anonymous LRU page > in elgible zones, OOM happened. > > balloon invoked oom-killer: gfp_mask=0x17080c0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOTRACK), nodemask=(null), order=0, oom_score_adj=0 > CPU: 7 PID: 1138 Comm: balloon Not tainted 4.11.0-rc6-mm1-zram-00289-ge228d67e9677-dirty #17 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 > Call Trace: > dump_stack+0x65/0x87 > dump_header.isra.19+0x8f/0x20f > ? preempt_count_add+0x9e/0xb0 > ? _raw_spin_unlock_irqrestore+0x24/0x40 > oom_kill_process+0x21d/0x3f0 > ? has_capability_noaudit+0x17/0x20 > out_of_memory+0xd8/0x390 > __alloc_pages_slowpath+0xbc1/0xc50 > ? anon_vma_interval_tree_insert+0x84/0x90 > __alloc_pages_nodemask+0x1a5/0x1c0 > pte_alloc_one+0x20/0x50 > __pte_alloc+0x1e/0x110 > __handle_mm_fault+0x919/0x960 > handle_mm_fault+0x77/0x120 > __do_page_fault+0x27a/0x550 > trace_do_page_fault+0x43/0x150 > do_async_page_fault+0x2c/0x90 > async_page_fault+0x28/0x30 > RIP: 0033:0x7fc4636bacb8 > RSP: 002b:00007fff97c9c4c0 EFLAGS: 00010202 > RAX: 00007fc3e818d000 RBX: 00007fc4639f8760 RCX: 00007fc46372e9ca > RDX: 0000000000101002 RSI: 0000000000101000 RDI: 0000000000000000 > RBP: 0000000000100010 R08: 00000000ffffffff R09: 0000000000000000 > R10: 0000000000000022 R11: 00000000000a3901 R12: 00007fc3e818d010 > R13: 0000000000101000 R14: 00007fc4639f87b8 R15: 00007fc4639f87b8 > Mem-Info: > active_anon:424716 inactive_anon:65314 isolated_anon:0 > active_file:52 inactive_file:46 isolated_file:0 > unevictable:0 dirty:27 writeback:0 unstable:0 > slab_reclaimable:3967 slab_unreclaimable:4125 > mapped:133 shmem:43 pagetables:1674 bounce:0 > free:4637 free_pcp:225 free_cma:0 > Node 0 active_anon:1698864kB inactive_anon:261256kB active_file:208kB inactive_file:184kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:532kB dirty:108kB writeback:0kB shmem:172kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no > DMA free:7316kB min:32kB low:44kB high:56kB active_anon:8064kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15992kB managed:15908kB mlocked:0kB slab_reclaimable:464kB slab_unreclaimable:40kB kernel_stack:0kB pagetables:24kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB > lowmem_reserve[]: 0 992 992 1952 > DMA32 free:9088kB min:2048kB low:3064kB high:4080kB active_anon:952176kB inactive_anon:0kB active_file:36kB inactive_file:0kB unevictable:0kB writepending:88kB present:1032192kB managed:1019388kB mlocked:0kB slab_reclaimable:13532kB slab_unreclaimable:16460kB kernel_stack:3552kB pagetables:6672kB bounce:0kB free_pcp:56kB local_pcp:24kB free_cma:0kB > lowmem_reserve[]: 0 0 0 959 > Movable free:3644kB min:1980kB low:2960kB high:3940kB active_anon:738560kB inactive_anon:261340kB active_file:188kB inactive_file:640kB unevictable:0kB writepending:20kB present:1048444kB managed:1010816kB mlocked:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:832kB local_pcp:60kB free_cma:0kB > lowmem_reserve[]: 0 0 0 0 > DMA: 1*4kB (E) 0*8kB 18*16kB (E) 10*32kB (E) 10*64kB (E) 9*128kB (ME) 8*256kB (E) 2*512kB (E) 2*1024kB (E) 0*2048kB 0*4096kB = 7524kB > DMA32: 417*4kB (UMEH) 181*8kB (UMEH) 68*16kB (UMEH) 48*32kB (UMEH) 14*64kB (MH) 3*128kB (M) 1*256kB (H) 1*512kB (M) 2*1024kB (M) 0*2048kB 0*4096kB = 9836kB > Movable: 1*4kB (M) 1*8kB (M) 1*16kB (M) 1*32kB (M) 0*64kB 1*128kB (M) 2*256kB (M) 4*512kB (M) 1*1024kB (M) 0*2048kB 0*4096kB = 3772kB > 378 total pagecache pages > 17 pages in swap cache > Swap cache stats: add 17325, delete 17302, find 0/27 > Free swap = 978940kB > Total swap = 1048572kB > 524157 pages RAM > 0 pages HighMem/MovableOnly > 12629 pages reserved > 0 pages cma reserved > 0 pages hwpoisoned > [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name > [ 433] 0 433 4904 5 14 3 82 0 upstart-udev-br > [ 438] 0 438 12371 5 27 3 191 -1000 systemd-udevd > > With investigation, skipping page of isolate_lru_pages makes reclaim > void because it returns zero nr_taken easily so LRU shrinking is > effectively nothing and just increases priority aggressively. > Finally, OOM happens. > > The problem is that get_scan_count determines nr_to_scan with > eligible zones so although priority drops to zero, it couldn't > reclaim any pages if the LRU contains mostly ineligible pages. > > get_scan_count: > > size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); > size = size >> sc->priority; > > Assumes sc->priority is 0 and LRU list is as follows. > > N-N-N-N-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H-H > > (Ie, small eligible pages are in the head of LRU but others are > almost ineligible pages) > > In that case, size becomes 4 so VM want to scan 4 pages but 4 pages > from tail of the LRU are not eligible pages. > If get_scan_count counts skipped pages, it doesn't reclaim any pages > remained after scanning 4 pages so it ends up OOM happening. > > This patch makes isolate_lru_pages try to scan pages until it > encounters eligible zones's pages. > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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