> > We used to have a schedule_timeout_killable(1) to address exactly that > > scenario but it was removed in 4.19: > > > > commit 9bfe5ded054b8e28a94c78580f233d6879a00146 > > Author: Michal Hocko <mhocko@xxxxxxxx> > > Date: Fri Aug 17 15:49:04 2018 -0700 > > > > mm, oom: remove sleep from under oom_lock > For the record: If I revert that commit, I can observe that current thread sleeps for more than one minute with oom_lock held. That is, I don't want to revert that commit. [ 1629.930998][T14021] idle-priority invoked oom-killer: gfp_mask=0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), order=0, oom_score_adj=0 [ 1629.934944][T14021] CPU: 0 PID: 14021 Comm: idle-priority Kdump: loaded Not tainted 5.6.0-rc5+ #968 [ 1629.938352][T14021] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/29/2019 [ 1629.942211][T14021] Call Trace: [ 1629.943956][T14021] dump_stack+0x71/0xa5 [ 1629.946041][T14021] dump_header+0x4d/0x3e0 [ 1629.948097][T14021] oom_kill_process+0x179/0x210 [ 1629.950191][T14021] out_of_memory+0x109/0x3d0 [ 1629.952154][T14021] ? out_of_memory+0x1ea/0x3d0 [ 1629.954349][T14021] __alloc_pages_slowpath+0x934/0xb89 [ 1629.956959][T14021] __alloc_pages_nodemask+0x333/0x370 [ 1629.959121][T14021] handle_pte_fault+0x4ce/0xb40 [ 1629.961274][T14021] __handle_mm_fault+0x2b2/0x5e0 [ 1629.963363][T14021] handle_mm_fault+0x177/0x360 [ 1629.965404][T14021] ? handle_mm_fault+0x46/0x360 [ 1629.967451][T14021] do_page_fault+0x2d5/0x680 [ 1629.969351][T14021] page_fault+0x34/0x40 [ 1629.971290][T14021] RIP: 0010:__clear_user+0x36/0x70 [ 1629.973621][T14021] Code: 0c a7 e2 95 53 48 89 f3 be 14 00 00 00 e8 82 87 b4 ff 0f 01 cb 48 89 d8 48 c1 eb 03 4c 89 e7 83 e0 07 48 89 d9 48 85 c9 74 0f <48> c7 07 00 00 00 00 48 83 c7 08 ff c9 75 f1 48 89 c1 85 c9 74 0a [ 1629.980104][T14021] RSP: 0000:ffffa06e0742bd40 EFLAGS: 00050202 [ 1629.982543][T14021] RAX: 0000000000000000 RBX: 0000000000000200 RCX: 0000000000000002 [ 1629.985322][T14021] RDX: 0000000000000000 RSI: 00000000a8057a95 RDI: 00007f0ca8605000 [ 1629.999883][T14021] RBP: ffffa06e0742bd50 R08: 0000000000000001 R09: 0000000000000000 [ 1630.018164][T14021] R10: 0000000000000000 R11: ffff953843a80978 R12: 00007f0ca8604010 [ 1630.021491][T14021] R13: 000000000c988000 R14: ffffa06e0742be08 R15: 0000000000001000 [ 1630.024881][T14021] clear_user+0x47/0x60 [ 1630.026651][T14021] iov_iter_zero+0x95/0x3d0 [ 1630.028455][T14021] read_iter_zero+0x38/0xb0 [ 1630.030234][T14021] new_sync_read+0x112/0x1b0 [ 1630.032025][T14021] __vfs_read+0x27/0x40 [ 1630.033639][T14021] vfs_read+0xaf/0x160 [ 1630.035243][T14021] ksys_read+0x62/0xe0 [ 1630.036869][T14021] __x64_sys_read+0x15/0x20 [ 1630.038827][T14021] do_syscall_64+0x4a/0x1e0 [ 1630.040515][T14021] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 1630.042598][T14021] RIP: 0033:0x7f109bb78950 [ 1630.044208][T14021] Code: Bad RIP value. [ 1630.045798][T14021] RSP: 002b:00007fff499db458 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 1630.048558][T14021] RAX: ffffffffffffffda RBX: 0000000200000000 RCX: 00007f109bb78950 [ 1630.051117][T14021] RDX: 0000000200000000 RSI: 00007f0c9bc7c010 RDI: 0000000000000003 [ 1630.053715][T14021] RBP: 00007f0c9bc7c010 R08: 0000000000000000 R09: 0000000000021000 [ 1630.056488][T14021] R10: 00007fff499daea0 R11: 0000000000000246 R12: 00007f0c9bc7c010 [ 1630.059124][T14021] R13: 0000000000000005 R14: 0000000000000003 R15: 0000000000000000 [ 1630.061935][T14021] Mem-Info: [ 1630.063226][T14021] active_anon:1314192 inactive_anon:5198 isolated_anon:0 [ 1630.063226][T14021] active_file:9 inactive_file:0 isolated_file:0 [ 1630.063226][T14021] unevictable:0 dirty:0 writeback:0 unstable:0 [ 1630.063226][T14021] slab_reclaimable:6649 slab_unreclaimable:268898 [ 1630.063226][T14021] mapped:1094 shmem:10475 pagetables:127946 bounce:0 [ 1630.063226][T14021] free:25585 free_pcp:62 free_cma:0 [ 1630.075882][T14021] Node 0 active_anon:5256768kB inactive_anon:20792kB active_file:36kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:4376kB dirty:0kB writeback:0kB shmem:41900kB shmem_thp: 0kB shmem_pmdmapped: 0kB anon_thp: 3158016kB writeback_tmp:0kB unstable:0kB all_unreclaimable? no [ 1630.084961][T14021] DMA free:15360kB min:132kB low:164kB high:196kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:15960kB managed:15360kB mlocked:0kB kernel_stack:0kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB [ 1630.094169][T14021] lowmem_reserve[]: 0 2717 7644 7644 [ 1630.096174][T14021] DMA32 free:43680kB min:23972kB low:29964kB high:35956kB reserved_highatomic:0KB active_anon:2733524kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB writepending:0kB present:3129152kB managed:2782468kB mlocked:0kB kernel_stack:0kB pagetables:4764kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB [ 1630.106132][T14021] lowmem_reserve[]: 0 0 4927 4927 [ 1630.108104][T14021] Normal free:43300kB min:43476kB low:54344kB high:65212kB reserved_highatomic:4096KB active_anon:2523244kB inactive_anon:20792kB active_file:36kB inactive_file:0kB unevictable:0kB writepending:0kB present:5242880kB managed:5045744kB mlocked:0kB kernel_stack:313872kB pagetables:507020kB bounce:0kB free_pcp:248kB local_pcp:248kB free_cma:0kB [ 1630.118473][T14021] lowmem_reserve[]: 0 0 0 0 [ 1630.120348][T14021] DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 1*1024kB (U) 1*2048kB (M) 3*4096kB (M) = 15360kB [ 1630.124316][T14021] DMA32: 0*4kB 0*8kB 2*16kB (UM) 2*32kB (UM) 1*64kB (U) 0*128kB 2*256kB (UM) 2*512kB (UM) 1*1024kB (M) 2*2048kB (UM) 9*4096kB (M) = 43680kB [ 1630.128773][T14021] Normal: 1231*4kB (UE) 991*8kB (UE) 343*16kB (UME) 230*32kB (UE) 117*64kB (UME) 65*128kB (UME) 7*256kB (UM) 0*512kB 0*1024kB 0*2048kB 0*4096kB = 43300kB [ 1630.134207][T14021] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB [ 1630.137435][T14021] Node 0 hugepages_total=0 hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB [ 1630.140770][T14021] 10478 total pagecache pages [ 1630.142789][T14021] 0 pages in swap cache [ 1630.144572][T14021] Swap cache stats: add 0, delete 0, find 0/0 [ 1630.146921][T14021] Free swap = 0kB [ 1630.148627][T14021] Total swap = 0kB [ 1630.150298][T14021] 2096998 pages RAM [ 1630.152078][T14021] 0 pages HighMem/MovableOnly [ 1630.154073][T14021] 136105 pages reserved [ 1630.156165][T14021] 0 pages cma reserved [ 1630.158028][T14021] oom-kill:constraint=CONSTRAINT_NONE,nodemask=(null),global_oom,task_memcg=/,task=normal-priority,pid=23173,uid=0 [ 1630.161867][T14021] Out of memory: Killed process 23173 (normal-priority) total-vm:4228kB, anon-rss:88kB, file-rss:0kB, shmem-rss:0kB, UID:0 pgtables:52kB oom_score_adj:1000 [ 1630.171681][ T18] oom_reaper: reaped process 23173 (normal-priority), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB (...snipped...) [ 1800.548694][ C0] idle-priority R running task 12416 14021 1183 0x80004080 [ 1800.550942][ C0] Call Trace: [ 1800.552116][ C0] __schedule+0x28c/0x860 [ 1800.553531][ C0] ? _raw_spin_unlock_irqrestore+0x2c/0x50 [ 1800.555293][ C0] schedule+0x5f/0xd0 [ 1800.556618][ C0] schedule_timeout+0x1ab/0x340 [ 1800.558151][ C0] ? __next_timer_interrupt+0xd0/0xd0 [ 1800.560069][ C0] schedule_timeout_killable+0x25/0x30 [ 1800.561836][ C0] out_of_memory+0x113/0x3d0 [ 1800.563519][ C0] ? out_of_memory+0x1ea/0x3d0 [ 1800.565040][ C0] __alloc_pages_slowpath+0x934/0xb89 [ 1800.566727][ C0] __alloc_pages_nodemask+0x333/0x370 [ 1800.568397][ C0] handle_pte_fault+0x4ce/0xb40 [ 1800.569944][ C0] __handle_mm_fault+0x2b2/0x5e0 [ 1800.571527][ C0] handle_mm_fault+0x177/0x360 [ 1800.573046][ C0] ? handle_mm_fault+0x46/0x360 [ 1800.574592][ C0] do_page_fault+0x2d5/0x680 [ 1800.576306][ C0] page_fault+0x34/0x40 [ 1800.578413][ C0] RIP: 0010:__clear_user+0x36/0x70
