请教内存分配失败的问题

zhaohuig

小弟是内核新手，请各位大神指点下什么情况下会导致以下错误产生？

httpd: page allocation failure: order:0, mode:0x200020
Pid: 11789, comm: httpd Tainted: G      D W    3.9.0-vv#1
Call Trace:
[<c109f537>] warn_alloc_failed+0xb7/0xf0
[<c10a15dc>] __alloc_pages_nodemask+0x52c/0x730
[<c10c7105>] cache_alloc_refill+0x2d5/0x5a0
[<c10c75b9>] kmem_cache_alloc+0x89/0x120
[<c10f16e4>] __bdi_start_writeback+0x24/0x80
[<c10f2351>] wakeup_flusher_threads+0x71/0x90
[<c10a8e64>] do_try_to_free_pages+0x164/0x350
[<c10a91ae>] try_to_free_pages+0xce/0x250
[<c104e400>] ? abort_exclusive_wait+0x80/0x80
[<c10a1523>] __alloc_pages_nodemask+0x473/0x730
[<c109bfe3>] find_or_create_page+0x43/0x90
[<c122e837>] alloc_extent_buffer+0xf7/0x440
[<c1207643>] btrfs_find_create_tree_block+0x23/0x30
[<c120785b>] read_tree_block+0x1b/0x50
[<c11e7623>] ? btrfs_release_path+0x33/0x90
[<c11ea54b>] read_block_for_search.isra.49+0x12b/0x3c0
[<c11ec2a6>] btrfs_search_slot+0x1f6/0x670
[<c1200c0d>] btrfs_lookup_dir_item+0x6d/0xa0
[<c121beec>] btrfs_lookup_dentry+0x8c/0x4a0
[<c10e4b5e>] ? __d_alloc+0xee/0x110
[<c10e4ddc>] ? d_alloc+0x4c/0x60
[<c121c30b>] btrfs_lookup+0xb/0x20
[<c10d9709>] lookup_real+0x19/0x50
[<c10dd8b0>] do_last+0x800/0xbf0
[<c10da9b1>] ? inode_permission+0x11/0x50
[<c10ddd40>] path_openat+0xa0/0x3e0
[<c108e957>] ? call_rcu+0x17/0x20
[<c10de31c>] do_filp_open+0x2c/0x80
[<c10d08c9>] do_sys_open+0xe9/0x1c0
[<c10d0000>] ? sys_faccessat+0xd0/0x1d0
[<c10d09c3>] sys_open+0x23/0x30
[<c161ddfa>] sysenter_do_call+0x12/0x22
Mem-Info:
DMA per-cpu:
CPU    0: hi:    0, btch:   1 usd:   0
CPU    1: hi:    0, btch:   1 usd:   0
CPU    2: hi:    0, btch:   1 usd:   0
CPU    3: hi:    0, btch:   1 usd:   0
CPU    4: hi:    0, btch:   1 usd:   0
CPU    5: hi:    0, btch:   1 usd:   0
CPU    6: hi:    0, btch:   1 usd:   0
CPU    7: hi:    0, btch:   1 usd:   0
Normal per-cpu:
CPU    0: hi:  186, btch:  31 usd:   0
CPU    1: hi:  186, btch:  31 usd:   0
CPU    2: hi:  186, btch:  31 usd:   0
CPU    3: hi:  186, btch:  31 usd:   0
CPU    4: hi:  186, btch:  31 usd:   0
CPU    5: hi:  186, btch:  31 usd:   0
CPU    6: hi:  186, btch:  31 usd:   0
CPU    7: hi:  186, btch:  31 usd:   0
HighMem per-cpu:
CPU    0: hi:  186, btch:  31 usd:   0
CPU    1: hi:  186, btch:  31 usd:   0
CPU    2: hi:  186, btch:  31 usd:   0
CPU    3: hi:  186, btch:  31 usd:   0
CPU    4: hi:  186, btch:  31 usd:   0
CPU    5: hi:  186, btch:  31 usd:   0
CPU    6: hi:  186, btch:  31 usd:   0
CPU    7: hi:  186, btch:  31 usd:   0
active_anon:460000 inactive_anon:129882 isolated_anon:0
active_file:1702405 inactive_file:50275 isolated_file:0
unevictable:0 dirty:185 writeback:88 unstable:0
free:1595978 slab_reclaimable:22626 slab_unreclaimable:80197
mapped:95701 shmem:143733 pagetables:36544 bounce:3
free_cma:0
DMA free:0kB min:68kB low:84kB high:100kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15968kB managed:15360kB mlocked:0kB dirty:0kB writeback:12kB mapped:0kB shmem:0kB slab_reclaimable:608kB slab_unreclaimable:6412kB kernel_stack:6160kB pagetables:548kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 696 16082 16082
Normal free:0kB min:3340kB low:4172kB high:5008kB active_anon:0kB inactive_anon:0kB active_file:356kB inactive_file:556kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:894968kB managed:712864kB mlocked:0kB dirty:0kB writeback:364kB mapped:108kB shmem:0kB slab_reclaimable:89896kB slab_unreclaimable:314376kB kernel_stack:108224kB pagetables:145628kB unstable:0kB bounce:12kB free_cma:0kB writeback_tmp:0kB pages_scanned:3791340 all_unreclaimable? no
lowmem_reserve[]: 0 0 123091 123091
HighMem free:6384056kB min:512kB low:18964kB high:37420kB active_anon:1840000kB inactive_anon:519528kB active_file:6809264kB inactive_file:200544kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15755764kB managed:15755764kB mlocked:0kB dirty:768kB writeback:0kB mapped:382696kB shmem:574932kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
DMA: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
Normal: 0*4kB 0*8kB 0*16kB 0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 0kB
HighMem: 23805*4kB (UM) 57532*8kB (UM) 61271*16kB (UM) 31562*32kB (UM) 9243*64kB (UM) 4135*128kB (UM) 1709*256kB (UM) 576*512kB (UM) 227*1024kB (UM) 106*2048kB (M) 375*4096kB (UMR) = 6384580kB
1895543 total pagecache pages
0 pages in swap cache
Swap cache stats: add 0, delete 0, find 0/0
Free swap  = 4194300kB
Total swap = 4194300kB
4322815 pages RAM
4094466 pages HighMem
201072 pages reserved
6005220 pages shared
630512 pages non-shared
SLAB: Unable to allocate memory on node 0 (gfp=0x20)
  cache: size-64, object size: 64, order: 0
  node 0: slabs: 3139/3139, objs: 185201/185201, free: 0

zhayun604863141

Open在内核里面的入口函数时sys_open,所以应该是open类的函数吧