Oom-killer（內存不足）帶有大量內存（？！） - inotify

Question

我正在面臨一個問題，將大量的文件夾放入（〜2000000）。 我改變了max_user_watches到8388608：

echo 8388608 > /proc/sys/fs/inotify/max_user_watches 

爲了支持手錶這個數量，服務器的3Gb可用內存。 但是，當我啓動inotify腳本，幾個小時後（〜15小時），它已被殺死。這裏是/ var/log/messages跟蹤：

inotify.sh invoked oom-killer: gfp_mask=0xd0, order=1, oom_adj=0 
inotify.sh cpuset=/ mems_allowed=0 
Pid: 12488, comm: inotify.sh Not tainted 2.6.32-5-686 #1 
Call Trace: 
[<c1089534>] ? oom_kill_process+0x60/0x201 
[<c1089ab1>] ? __out_of_memory+0xf4/0x107 
[<c1089b1e>] ? out_of_memory+0x5a/0x7c 
[<c108c3c9>] ? __alloc_pages_nodemask+0x3ef/0x4d9 
[<c108c4bf>] ? __get_free_pages+0xc/0x17 
[<c102f06c>] ? copy_process+0xb7/0xf28 
[<c11028ad>] ? security_file_alloc+0xc/0xd 
[<c1030017>] ? do_fork+0x13a/0x2bc 
[<c10b182d>] ? fd_install+0x1e/0x3c 
[<c103b996>] ? recalc_sigpending+0xf/0x2e 
[<c103bcae>] ? sigprocmask+0x9d/0xbc 
[<c1001dae>] ? sys_clone+0x21/0x27 
[<c10030fb>] ? sysenter_do_call+0x12/0x28 
Mem-Info: 
DMA per-cpu: 
CPU 0: hi: 0, btch: 1 usd: 0 
CPU 1: hi: 0, btch: 1 usd: 0 
Normal per-cpu: 
CPU 0: hi: 186, btch: 31 usd: 0 
CPU 1: hi: 186, btch: 31 usd: 41 
HighMem per-cpu: 
CPU 0: hi: 186, btch: 31 usd: 0 
CPU 1: hi: 186, btch: 31 usd: 34 
active_anon:53061 inactive_anon:13287 isolated_anon:0 
active_file:2006 inactive_file:4143 isolated_file:0 
unevictable:0 dirty:272 writeback:0 unstable:0 
free:499244 slab_reclaimable:174921 slab_unreclaimable:25041 
mapped:1892 shmem:42 pagetables:240 bounce:0 
DMA free:3492kB min:64kB low:80kB high:96kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15804kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:12080kB slab_unreclaimable:332kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes 
lowmem_reserve[]: 0 861 3032 3032 
Normal free:59488kB min:3720kB low:4648kB high:5580kB active_anon:0kB inactive_anon:0kB active_file:1092kB inactive_file:3380kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:881880kB mlocked:0kB dirty:1088kB writeback:0kB mapped:4kB shmem:0kB slab_reclaimable:687604kB slab_unreclaimable:99832kB kernel_stack:952kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:1211 all_unreclaimable? yes 
lowmem_reserve[]: 0 0 17366 17366 
HighMem free:1933996kB min:512kB low:2856kB high:5200kB active_anon:212244kB inactive_anon:53148kB active_file:6932kB inactive_file:13192kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:2222948kB mlocked:0kB dirty:0kB writeback:0kB mapped:7564kB shmem:168kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:960kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no 
lowmem_reserve[]: 0 0 0 0 
DMA: 19*4kB 43*8kB 16*16kB 6*32kB 17*64kB 12*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 3492kB 
Normal: 14406*4kB 99*8kB 1*16kB 3*32kB 1*64kB 1*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 59488kB 
HighMem: 31*4kB 14*8kB 8*16kB 2*32kB 2*64kB 1*128kB 2*256kB 1*512kB 1*1024kB 1*2048kB 471*4096kB = 1933996kB 
6194 total pagecache pages 
0 pages in swap cache 
Swap cache stats: add 0, delete 0, find 0/0 
Free swap = 1951736kB 
Total swap = 1951736kB 
786416 pages RAM 
560130 pages HighMem 
7712 pages reserved 
7694 pages shared 
275891 pages non-shared 

當腳本被殺死時，我有將近2GB的可用內存。所以我不太瞭解這個OOM。有人能幫我嗎 ？ 腳本很簡單，只要：

#!/bin/bash 

INOTIFY_DIR="/data" 
inotifywait -rme modify,attrib,move,close_write,create,delete,delete_self $INOTIFY_DIR 2>> /datatest/inotify.log 

Answer 1

的OOM殺手與page_fault_handler()有關。如果page_fault_handler由於不可用而無法分配頁面，它將通過內核調用page_fault_out_of_memory()調用OOM殺手。然後，OOM殺手邏輯將啓動並選擇最佳候選進程來殺死和清理內存。邏輯遵循一種啓發式的方法來尋找最具殺傷力的過程，以便釋放內存並保持系統活躍。

爲什麼OOM殺手踢是純粹基於免費網頁的可用性。這可能是來自任何內存區域的頁面分配失敗。您擁有足夠大的可用內存並不意味着您擁有所有其他區域的內存。等ZONE_DMA，低MEM等

採取在oom_kill.cpage_fault_out_of_memory()有關OOM殺手算法