检查日志：
httpd: page allocation failure. order:4, mode:0xd0
Call Trace:
[<ffffffff8000f696>] __alloc_pages+0x2ef/0x308
[<ffffffff80017a40>] cache_grow+0x139/0x3c7
[<ffffffff8005bd54>] cache_alloc_refill+0x138/0x188
[<ffffffff800df358>] __kmalloc+0x95/0x9f
[<ffffffff800f0bba>] alloc_fd_array+0x18/0x28
[<ffffffff800306c8>] expand_files+0x124/0x2cb
[<ffffffff800226c5>] dup_fd+0x133/0x281
[<ffffffff80049050>] copy_files+0x47/0x64
[<ffffffff8001f632>] copy_process+0x590/0x15db
[<ffffffff800a11c4>] alloc_pid+0x228/0x2c4
[<ffffffff80030f6c>] do_fork+0x69/0x1c1
[<ffffffff8005d116>] system_call+0x7e/0x83
[<ffffffff8005d427>] ptregscall_common+0x67/0xac
Mem-info:
Node 0 DMA per-cpu:
cpu 0 hot: high 0, batch 1 used:0
cpu 0 cold: high 0, batch 1 used:0
cpu 1 hot: high 0, batch 1 used:0
cpu 1 cold: high 0, batch 1 used:0
cpu 2 hot: high 0, batch 1 used:0
cpu 2 cold: high 0, batch 1 used:0
cpu 3 hot: high 0, batch 1 used:0
cpu 3 cold: high 0, batch 1 used:0
cpu 4 hot: high 0, batch 1 used:0
cpu 4 cold: high 0, batch 1 used:0
cpu 5 hot: high 0, batch 1 used:0
cpu 5 cold: high 0, batch 1 used:0
cpu 6 hot: high 0, batch 1 used:0
cpu 6 cold: high 0, batch 1 used:0
cpu 7 hot: high 0, batch 1 used:0
cpu 7 cold: high 0, batch 1 used:0
Node 0 DMA32 per-cpu:
cpu 0 hot: high 186, batch 31 used:14
cpu 0 cold: high 62, batch 15 used:57
cpu 1 hot: high 186, batch 31 used:29
cpu 1 cold: high 62, batch 15 used:58
cpu 2 hot: high 186, batch 31 used:30
cpu 2 cold: high 62, batch 15 used:57
cpu 3 hot: high 186, batch 31 used:30
cpu 3 cold: high 62, batch 15 used:56
cpu 4 hot: high 186, batch 31 used:26
cpu 4 cold: high 62, batch 15 used:13
cpu 5 hot: high 186, batch 31 used:8
cpu 5 cold: high 62, batch 15 used:42
cpu 6 hot: high 186, batch 31 used:30
cpu 6 cold: high 62, batch 15 used:50
cpu 7 hot: high 186, batch 31 used:157
cpu 7 cold: high 62, batch 15 used:59
Node 0 Normal per-cpu:
cpu 0 hot: high 186, batch 31 used:13
cpu 0 cold: high 62, batch 15 used:50
cpu 1 hot: high 186, batch 31 used:66
cpu 1 cold: high 62, batch 15 used:49
cpu 2 hot: high 186, batch 31 used:3
cpu 2 cold: high 62, batch 15 used:55
cpu 3 hot: high 186, batch 31 used:104
cpu 3 cold: high 62, batch 15 used:55
cpu 4 hot: high 186, batch 31 used:2
cpu 4 cold: high 62, batch 15 used:2
cpu 5 hot: high 186, batch 31 used:87
cpu 5 cold: high 62, batch 15 used:3
cpu 6 hot: high 186, batch 31 used:15
cpu 6 cold: high 62, batch 15 used:55
cpu 7 hot: high 186, batch 31 used:113
cpu 7 cold: high 62, batch 15 used:12
Node 0 HighMem per-cpu: empty
Free pages: 76972kB (0kB HighMem)
Active:3061605 inactive:620399 dirty:68055 writeback:0 unstable:0 free:19243 slab:283635 mapped-file:33024 mapped-anon:2758457 pagetables:91114
Node 0 DMA free:10032kB min:8kB low:8kB high:12kB active:0kB inactive:0kB present:9628kB pages_scanned:0 all_unreclaimable? yes
lowmem_reserve[]: 0 3451 16066 16066
Node 0 DMA32 free:53992kB min:3484kB low:4352kB high:5224kB active:2704704kB inactive:367984kB present:3534588kB pages_scanned:268 all_unreclaimable? no
lowmem_reserve[]: 0 0 12615 12615
Node 0 Normal free:12948kB min:12732kB low:15912kB high:19096kB active:9541756kB inactive:2113612kB present:12917900kB pages_scanned:423 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
Node 0 HighMem free:0kB min:128kB low:128kB high:128kB active:0kB inactive:0kB present:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
Node 0 DMA: 4*4kB 2*8kB 3*16kB 3*32kB 2*64kB 2*128kB 1*256kB 0*512kB 1*1024kB 0*2048kB 2*4096kB = 10032kB
Node 0 DMA32: 0*4kB 59*8kB 45*16kB 82*32kB 0*64kB 6*128kB 5*256kB 0*512kB 1*1024kB 1*2048kB 11*4096kB = 53992kB
Node 0 Normal: 47*4kB 187*8kB 356*16kB 148*32kB 1*64kB 0*128kB 1*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 12948kB
Node 0 HighMem: empty
923737 pagecache pages
Swap cache: add 180089, delete 179928, find 2859/3518, race 0+0
Free swap = 8304596kB
Total swap = 8388600kB
Free swap: 8304596kB
4322816 pages of RAM
230069 reserved pages
14241581 pages shared
117 pages swap cached
我的 /etc/fstab（SWAP 是 SSD 上的文件）：
proc /proc proc defaults 0 0
none /dev/pts devpts gid=5,mode=620 0 0
tmpfs /dev/shm tmpfs defaults 0 0
/dev/md0 /boot ext3 defaults 0 0
/dev/md1 / ext4 rw,noatime,nodiratime,usrjquota=aquota.user,grpjquota=aquota.group,usrquota,grpquota,jqfmt=vfsv0 0 0
/dev/md2 /home ext4 rw,noatime,nodiratime,usrjquota=aquota.user,grpjquota=aquota.group,usrquota,grpquota,jqfmt=vfsv0 0 0
UUID=b422827c-9f2f-4bc5-ab5a-3cc921924daa /var/lib/mysql ext4 rw,noatime,nodiratime,usrjquota=aquota.user,grpjquota=aquota.group,usrquota,grpquota,jqfmt=vfsv0, 1 1
/var/lib/mysql/swapfile1 swap swap defaults 0 0
Swapiness 设置为 20：
cat /proc/sys/vm/swappiness
20
只剩下少量的 RAM 并且仍然使用非常低的 SWAP 直到它崩溃并且 RAM 被释放并且我在几个小时内再次崩溃：
Mem: 16370988k total, 16200724k used, 170264k free, 250340k buffers
Swap: 8388600k total, 83356k used, 8305244k free, 859484k cached
答案1
/proc//oom_adj 是什么？
内存需求如何变化 - 突然增加可能表明您已达到 2Gb 的限制。缓慢增加意味着您肯定将 maxclients 设置得太高，并且可能需要更多硬件。使用大型机器作为 Web 服务器毫无意义 - 请使用几个较小的机器。
内核版本是什么-参见此错误报告（和别的）。