[ceph-users] OSD killed by OOM when many cache available

Sam Huracan nowitzki.sammy at gmail.com
Fri Nov 17 18:03:02 PST 2017


@Eric: How can I check status of fscache? Why can it be root cause?

Thanks

2017-11-18 7:30 GMT+07:00 Eric Nelson <ericnelson at gmail.com>:

> One thing that doesn't show up is fs cache, which is likely the cause
> here. We went through this on our SSDs and had to add the following to stop
> the crashes. I believe vm.vfs_cache_pressure and min_free_kbytes were the
> really helpful things in getting the crashes to stop. HTH!
>
> sysctl_param 'vm.vfs_cache_pressure' do
>
>   value 400
>
> end
>
> sysctl_param 'vm.dirty_ratio' do
>
>   value 20
>
> end
>
> sysctl_param 'vm.dirty_background_ratio' do
>
>   value 2
>
> end
>
> sysctl_param 'vm.min_free_kbytes' do
>
>   value 4194304
>
> end
>
>
>
> On Fri, Nov 17, 2017 at 4:24 PM, Sam Huracan <nowitzki.sammy at gmail.com>
> wrote:
>
>> I see some more logs about memory in syslog:
>>
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553749] Node 0 DMA free:14828kB
>> min:32kB low:40kB high:48kB active_anon:0kB inactive_anon:0kB
>> active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB
>> isolated(file):0kB present:15996kB managed:15896kB mlocked:0kB dirty:0kB
>> writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB
>> slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB
>> bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB
>> pages_scanned:0 all_unreclaimable? yes
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553753] lowmem_reserve[]: 0 1830
>> 32011 32011 32011
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553755] Node 0 DMA32 free:134848kB
>> min:3860kB low:4824kB high:5788kB active_anon:120628kB
>> inactive_anon:121792kB active_file:653404kB inactive_file:399272kB
>> unevictable:0kB isolated(anon):0kB isolated(file):36kB present:1981184kB
>> managed:1900752kB mlocked:0kB dirty:344kB writeback:0kB mapped:1200kB
>> shmem:0kB slab_reclaimable:239900kB slab_unreclaimable:154560kB
>> kernel_stack:43376kB pagetables:1176kB unstable:0kB bounce:0kB free_pcp:0kB
>> local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0
>> all_unreclaimable? no
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553758] lowmem_reserve[]: 0 0
>> 30180 30180 30180
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553760] Node 0 Normal
>> free:237232kB min:63684kB low:79604kB high:95524kB active_anon:3075228kB
>> inactive_anon:629052kB active_file:12544336kB inactive_file:12570716kB
>> unevictable:0kB isolated(anon):0kB isolated(file):0kB present:31457280kB
>> managed:30905084kB mlocked:0kB dirty:74368kB writeback:3796kB
>> mapped:48516kB shmem:1276kB slab_reclaimable:713684kB
>> slab_unreclaimable:416404kB kernel_stack:40896kB pagetables:25288kB
>> unstable:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
>> writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553763] lowmem_reserve[]: 0 0 0 0 0
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553765] Node 0 DMA: 1*4kB (U)
>> 1*8kB (U) 0*16kB 1*32kB (U) 3*64kB (U) 2*128kB (U) 0*256kB 0*512kB 0*1024kB
>> 1*2048kB (M) 3*4096kB (M) = 14828kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553772] Node 0 DMA32: 10756*4kB
>> (UME) 11442*8kB (UME) 25*16kB (UE) 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB
>> 0*1024kB 0*2048kB 0*4096kB = 134960kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553777] Node 0 Normal: 59473*4kB
>> (UME) 77*8kB (U) 10*16kB (H) 8*32kB (H) 6*64kB (H) 2*128kB (H) 1*256kB (H)
>> 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 240332kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553784] Node 0 hugepages_total=0
>> hugepages_free=0 hugepages_surp=0 hugepages_size=1048576kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553784] Node 0 hugepages_total=0
>> hugepages_free=0 hugepages_surp=0 hugepages_size=2048kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553785] 6544612 total pagecache
>> pages
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553786] 2347 pages in swap cache
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553787] Swap cache stats: add
>> 2697126, delete 2694779, find 38874122/39241548
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553788] Free swap  = 61498092kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553788] Total swap = 62498812kB
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553789] 8363615 pages RAM
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553790] 0 pages HighMem/MovableOnly
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553790] 158182 pages reserved
>> Nov 17 10:47:17 ceph1 kernel: [2810698.553791] 0 pages cma reserved
>>
>> Is it relate to page caches?
>>
>> 2017-11-18 7:22 GMT+07:00 Sam Huracan <nowitzki.sammy at gmail.com>:
>>
>>> Today, one of our Ceph OSDs was down, I've check syslog and see this OSD
>>> process was killed by OMM
>>>
>>>
>>> Nov 17 10:01:06 ceph1 kernel: [2807926.762304] Out of memory: Kill
>>> process 3330 (ceph-osd) score 7 or sacrifice child
>>> Nov 17 10:01:06 ceph1 kernel: [2807926.763745] Killed process 3330
>>> (ceph-osd) total-vm:2372392kB, anon-rss:559084kB, file-rss:7268kB
>>> Nov 17 10:01:06 ceph1 kernel: [2807926.985830] init: ceph-osd (ceph/6)
>>> main process (3330) killed by KILL signal
>>> Nov 17 10:01:06 ceph1 kernel: [2807926.985844] init: ceph-osd (ceph/6)
>>> main process ended, respawning
>>> Nov 17 10:03:39 ceph1 bash: root [15524]: sudo ceph health detail [0]
>>> Nov 17 10:03:40 ceph1 bash: root [15524]: sudo ceph health detail [0]
>>> Nov 17 10:17:01 ceph1 CRON[75167]: (root) CMD (   cd / && run-parts
>>> --report /etc/cron.hourly)
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553690] ceph-status.sh invoked
>>> oom-killer: gfp_mask=0x26000c0, order=2, oom_score_adj=0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553693] ceph-status.sh cpuset=/
>>> mems_allowed=0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553697] CPU: 5 PID: 194271 Comm:
>>> ceph-status.sh Not tainted 4.4.0-62-generic #83~14.04.1-Ubuntu
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553698] Hardware name: Dell Inc.
>>> PowerEdge R730xd/072T6D, BIOS 2.5.5 08/16/2017
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553699]  0000000000000000
>>> ffff88001a857b38 ffffffff813dc4ac ffff88001a857cf0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553701]  0000000000000000
>>> ffff88001a857bc8 ffffffff811fb066 ffff88083d29e200
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553703]  ffff88001a857cf0
>>> ffff88001a857c00 ffff8808453cf000 0000000000000000
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553704] Call Trace:
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553709]  [<ffffffff813dc4ac>]
>>> dump_stack+0x63/0x87
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553713]  [<ffffffff811fb066>]
>>> dump_header+0x5b/0x1d5
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553717]  [<ffffffff81188b75>]
>>> oom_kill_process+0x205/0x3d0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553718]  [<ffffffff8118857e>] ?
>>> oom_unkillable_task+0x9e/0xc0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553720]  [<ffffffff811891ab>]
>>> out_of_memory+0x40b/0x460
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553722]  [<ffffffff811fbb1f>]
>>> __alloc_pages_slowpath.constprop.87+0x742/0x7ad
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553725]  [<ffffffff8118e1a7>]
>>> __alloc_pages_nodemask+0x237/0x240
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553727]  [<ffffffff8118e36d>]
>>> alloc_kmem_pages_node+0x4d/0xd0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553730]  [<ffffffff8107c125>]
>>> copy_process+0x185/0x1ce0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553732]  [<ffffffff813320f3>] ?
>>> security_file_alloc+0x33/0x50
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553734]  [<ffffffff8107de1a>]
>>> _do_fork+0x8a/0x310
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553737]  [<ffffffff8108dc01>] ?
>>> sigprocmask+0x51/0x80
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553738]  [<ffffffff8107e149>]
>>> SyS_clone+0x19/0x20
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553743]  [<ffffffff81802d36>]
>>> entry_SYSCALL_64_fastpath+0x16/0x75
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553744] Mem-Info:
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747] active_anon:798964
>>> inactive_anon:187711 isolated_anon:0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747]  active_file:3299435
>>> inactive_file:3242497 isolated_file:9
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747]  unevictable:0
>>> dirty:18678 writeback:949 unstable:0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747]  slab_reclaimable:238396
>>> slab_unreclaimable:142741
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747]  mapped:12429 shmem:319
>>> pagetables:6616 bounce:0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553747]  free:96727 free_pcp:0
>>> free_cma:0
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553749] Node 0 DMA free:14828kB
>>> min:32kB low:40kB high:48kB active_anon:0kB inactive_anon:0kB
>>> active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB
>>> isolated(file):0kB present:15996kB managed:15896kB mlocked:0kB dirty:0kB
>>> writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB
>>> slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB
>>> bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB writeback_tmp:0kB
>>> pages_scanned:0 all_unreclaimable? yes
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553753] lowmem_reserve[]: 0 1830
>>> 32011 32011 32011
>>> Nov 17 10:47:17 ceph1 kernel: [2810698.553755] Node 0 DMA32
>>> free:134848kB min:3860kB low:4824kB high:5788kB active_anon:120628kB
>>> inactive_anon:121792kB active_file:653404kB inactive_file:399272kB
>>> unevictable:0kB isolated(anon):0kB isolated(file):36kB present:1981184kB
>>> managed:1900752kB mlocked:0kB dirty:344kB writeback:0kB mapped:1200kB
>>> shmem:0kB slab_reclaimable:239900kB slab_unreclaimable:154560kB
>>> kernel_stack:43376kB pagetables:1176kB unstable:0kB bounce:0kB free_pcp:0kB
>>> local_pcp:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0
>>> all_unreclaimable? no
>>>
>>>
>>> We check free Memory, Cache is free 24,705 MB
>>>
>>> root at ceph1:/var/log# free -m
>>>              total       used       free     shared    buffers     cached
>>> Mem:         32052      31729        323          1        125      24256
>>> -/+ buffers/cache:       7347      24705
>>> Swap:        61033        120      60913
>>>
>>>
>>>
>>> It's so weird. Could you help me solve this problem, I'm afraid it 'll
>>> come again.
>>>
>>> Thanks in advance.
>>>
>>>
>>>
>>>
>>
>> _______________________________________________
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>>
>>
>
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