oom-killer

内存不够时系统会启动oom-killer

~ # xxx_test 192.168.1.29 192.168.1.71

rtl8168: eth0: link up

info [create_socket_srv:354]: listening on port : 6789

info [listen_func:304]: connection[4] : 192.168.1.71:43786

[process_cmd:365]: $taes #cd

ft2_test invoked oom-killer: gfp_mask=0x200da, order=0, oom_score_adj=0

CPU: 0 PID: 107 Comm: ft2_test Not tainted 3.10.27+ #401

Stack : 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000

00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 8efc9b98

…

Call Trace:[<800144f4>] 0x800144f4

[<800144f4>] 0x800144f4

[<80446c20>] 0x80446c20

[<80189f04>] 0x80189f04

[<80066744>] 0x80066744

[<80028420>] 0x80028420

[<800665e8>] 0x800665e8

[<80066568>] 0x80066568

[<80066ff0>] 0x80066ff0

[<8006a648>] 0x8006a648

[<8018ed24>] 0x8018ed24

[<8007ba94>] 0x8007ba94

[<8007e370>] 0x8007e370

[<8007e040>] 0x8007e040

[<800804a8>] 0x800804a8

[<8007bc88>] 0x8007bc88

[<80017428>] 0x80017428

[<800809c4>] 0x800809c4

[<8018add4>] 0x8018add4

[<80073cdc>] 0x80073cdc

[<8007f76c>] 0x8007f76c

[<8018add4>] 0x8018add4

[<8007eeac>] 0x8007eeac

[<80011ba4>] 0x80011ba4

[<8018eb98>] 0x8018eb98

Mem-Info:

Normal per-cpu:

CPU 0: hi: 90, btch: 15 usd: 33

active_anon:42496 inactive_anon:0 isolated_anon:0

active_file:0 inactive_file:2 isolated_file:0

unevictable:958 dirty:0 writeback:0 unstable:0

free:427 slab_reclaimable:163 slab_unreclaimable:343

mapped:156 shmem:0 pagetables:54 bounce:0

free_cma:0

Normal free:1708kB min:1728kB low:2160kB high:2592kB active_anon:169984kB inactive_anon:0kB active_file:0kB inactive_file:8kB unevictable:3832kB isolated(anon):0kB isolated(file):0kB present:262144kB managed:187256kB mlocked:0kB dirty:0kB writeback:0kB mapped:624kB shmem:0kB slab_reclaimable:652kB slab_unreclaimable:1372kB kernel_stack:272kB pagetables:216kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:46 all_unreclaimable? yes

lowmem_reserve[]: 0 0

Normal: 1*4kB (M) 1*8kB (U) 2*16kB (UM) 0*32kB 2*64kB (UM) 0*128kB 0*256kB 1*512kB (M) 1*1024kB (M) 0*2048kB 0*4096kB = 1708kB

960 total pagecache pages

65536 pages RAM

18347 pages reserved

270083 pages shared

44021 pages non-shared

[ pid ] uid tgid total_vm rss nr_ptes swapents oom_score_adj name

[ 84] 0 84 214 96 3 0 0 sh

[ 96] 0 96 46273 42577 48 0 0 ft2_test

Out of memory: Kill process 96 (ft2_test) score 873 or sacrifice child

Killed process 96 (ft2_test) total-vm:185092kB, anon-rss:169872kB, file-rss:436kB

Killed

oom-killer

oom-killer相关的内核代码位置在mm/oom-kill.c

oom-killer会在内存紧张的时候，依次kill内存占用较高的进程，发送signal 15(SIGTERM)，并在/var/log/message中进行记录。

Oom-kill杀死进程的机制

/proc/vm/oom_adj 表示该pid进程被oom killer杀掉的权重，在[-17, 15]之间，越高的权重，意味着越有可能被oom-killer选中，-17表示禁止被kill掉。

/proc/vm/oom_score 当前进程被kill的分数，越高的分数，意味着越有可能被kill