On 06/25/2015 04:45 PM, Michal Hocko wrote: > On Thu 25-06-15 16:29:31, Nikolay Borisov wrote: >> I couldn't find any particular OOM which stands out, here how a typical >> one looks like: >> >> alxc9 kernel: Memory cgroup out of memory (oom_kill_allocating_task): Kill process 9703 (postmaster) score 0 or sacrifice child >> alxc9 kernel: Killed process 9703 (postmaster) total-vm:205800kB, anon-rss:1128kB, file-rss:0kB >> alxc9 kernel: php invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0 >> alxc9 kernel: php cpuset=cXXXX mems_allowed=0-1 >> alxc9 kernel: CPU: 12 PID: 1000 Comm: php Not tainted 4.0.0-clouder9+ #31 >> alxc9 kernel: Hardware name: Supermicro X9DRD-7LN4F(-JBOD)/X9DRD-EF/X9DRD-7LN4F, BIOS 3.2 01/16/2015 >> alxc9 kernel: ffff8805d8440400 ffff88208d863c78 ffffffff815aaca3 ffff8820b947c750 >> alxc9 kernel: ffff8820b947c750 ffff88208d863cc8 ffffffff81123b2e ffff882000000000 >> alxc9 kernel: ffffffff000000d0 ffff8805d8440400 ffff8820b947c750 ffff8820b947cee0 >> alxc9 kernel: Call Trace: >> alxc9 kernel: [<ffffffff815aaca3>] dump_stack+0x48/0x5d >> alxc9 kernel: [<ffffffff81123b2e>] dump_header+0x8e/0xe0 >> alxc9 kernel: [<ffffffff81123fa7>] oom_kill_process+0x1d7/0x3c0 >> alxc9 kernel: [<ffffffff810d85a1>] ? cpuset_mems_allowed_intersects+0x21/0x30 >> alxc9 kernel: [<ffffffff8118c2bd>] mem_cgroup_out_of_memory+0x2bd/0x370 >> alxc9 kernel: [<ffffffff81189b37>] ? mem_cgroup_iter+0x177/0x390 >> alxc9 kernel: [<ffffffff8118c5d7>] mem_cgroup_oom_synchronize+0x267/0x290 >> alxc9 kernel: [<ffffffff811874f0>] ? mem_cgroup_wait_acct_move+0x140/0x140 >> alxc9 kernel: [<ffffffff81124504>] pagefault_out_of_memory+0x24/0xe0 >> alxc9 kernel: [<ffffffff81041927>] mm_fault_error+0x47/0x160 >> alxc9 kernel: [<ffffffff81041db0>] __do_page_fault+0x340/0x3c0 >> alxc9 kernel: [<ffffffff81041e6c>] do_page_fault+0x3c/0x90 >> alxc9 kernel: [<ffffffff815b1758>] page_fault+0x28/0x30 >> alxc9 kernel: Task in /lxc/cXXXX killed as a result of limit of /lxc/cXXXX >> alxc9 kernel: memory: usage 2097152kB, limit 2097152kB, failcnt 7832302 >> alxc9 kernel: memory+swap: usage 2097152kB, limit 2621440kB, failcnt 0 >> alxc9 kernel: kmem: usage 0kB, limit 9007199254740988kB, failcnt 0 >> alxc9 kernel: Memory cgroup stats for /lxc/cXXXX: cache:22708KB rss:2074444KB rss_huge:0KB >> mapped_file:19960KB writeback:4KB swap:0KB inactive_anon:20364KB active_anon:2074896KB >> inactive_file:1236KB active_file:464KB unevictable:0KB >> >> The backtrace for other processes is exactly the same. > > OK, so this is not the global OOM killer. That wasn't clear from your > previous description. It makes a difference because it means that the > system is still healthy globaly and allocation requests will not loop > for ever in the allocator. Memcg charging path will not get blocked > until the OOM resolves and return ENOMEM when not called from the page > fault path. Yes, overall, the machine is healthy, only the processes for a particular container would all go into uninterruptible sleep. > > memcg oom killer ignores oom_kill_allocating_task so the victim might be > different from the current task. That means the victim might get stuck > behind a lock held by somebody else. If the ext4 journaling code depends > on memcg charges and retry endlessly then the waiters would get stuck as > well. I've patched the cgroup OOM so that it takes into account the oom_kill_allocating_task. > > I can see some calls to find_or_create_page from fs/ext4/mballoc.c but > AFAIU they are handling ENOMEM and lead to transaction abort - but I am > not familiar with this code enough so somebody familiar with ext4 should > double check that. > > This all suggests that your lockup is caused by something else than OOM > most probably. > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
