On Tue, 14 Jul 2015, Xuzhichuang wrote: > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138764] iostat invoked oom-killer: gfp_mask=0xd0, order=2, oom_adj=0, oom_score_adj=0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138769] iostat cpuset=/ mems_allowed=0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138773] Pid: 18117, comm: iostat Tainted: P W NX 3.0.58-0.6.6-xen #1 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138775] Call Trace: > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138800] [<ffffffff800088be>] dump_trace+0x6e/0x1a0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138810] [<ffffffff803f773d>] dump_stack+0x69/0x6f > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138821] [<ffffffff800dbced>] dump_header+0x9d/0x120 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138826] [<ffffffff800dc505>] oom_kill_process+0x95/0x1a0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138830] [<ffffffff800dc746>] out_of_memory+0x136/0x220 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138834] [<ffffffff800e0fda>] __alloc_pages_slowpath+0x7ba/0x810 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138838] [<ffffffff800e1219>] __alloc_pages_nodemask+0x1e9/0x200 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138845] [<ffffffff8011ae38>] cache_grow+0x348/0x450 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138850] [<ffffffff8011b243>] cache_alloc_refill+0x303/0x4d0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138854] [<ffffffff8011ba70>] __kmalloc+0x1b0/0x290 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138862] [<ffffffff8014c1da>] seq_read+0x13a/0x3b0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138869] [<ffffffff8018a762>] proc_reg_read+0x92/0xe0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138877] [<ffffffff80129877>] vfs_read+0xc7/0x130 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138881] [<ffffffff801299e3>] sys_read+0x53/0xa0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138887] [<ffffffff80402d73>] system_call_fastpath+0x16/0x1b > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138922] [<00007f935f57f4c0>] 0x7f935f57f4bf > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138923] Mem-Info: > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138925] DMA per-cpu: > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138927] CPU 0: hi: 0, btch: 1 usd: 0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138929] CPU 1: hi: 0, btch: 1 usd: 0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138930] DMA32 per-cpu: > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138932] CPU 0: hi: 155, btch: 38 usd: 11 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138933] CPU 1: hi: 155, btch: 38 usd: 0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138936] active_anon:227111 inactive_anon:10382 isolated_anon:0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138937] active_file:203 inactive_file:189 isolated_file:47 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138938] unevictable:95395 dirty:0 writeback:0 unstable:0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138939] free:247834 slab_reclaimable:18187 slab_unreclaimable:53853 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138940] mapped:11485 shmem:11167 pagetables:0 bounce:0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138945] DMA free:984kB min:36kB low:44kB high:52kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:16160kB 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 writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138949] lowmem_reserve[]: 0 3014 3014 3014 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138955] DMA32 free:990352kB min:7004kB low:8752kB high:10504kB active_anon:908444kB inactive_anon:41528kB active_file:812kB inactive_file:756kB unevictable:381580kB isolated(anon):0kB isolated(file):188kB present:3025264kB mlocked:381580kB dirty:0kB writeback:0kB mapped:45940kB shmem:44668kB slab_reclaimable:72748kB slab_unreclaimable:215412kB kernel_stack:12456kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:192 all_unreclaimable? no > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138960] lowmem_reserve[]: 0 0 0 0 > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138962] DMA: 2*4kB 4*8kB 3*16kB 4*32kB 2*64kB 1*128kB 2*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 984kB > Jul 10 12:33:03 BMS_CNA04 kernel: [18136514.138968] DMA32: 188513*4kB 29459*8kB 2*16kB 2*32kB 1*64kB 0*128kB 0*256kB 1*512kB 0*1024kB 0*2048kB 0*4096kB = 990396kB The problem is most of your memory for ZONE_DMA32 is available only in sizes of order-0 and order-1 and the slab allocator is trying to allocate order-2 memory with no possibility of fallback to a smaller order. You're running on a 3.0.58 kernel, but the watermark calculation should be the same in recent kernels. If you follow the logic of __zone_watermark_ok(), which uses the same watermarks as printed above, the min watermark for this zone is 1751 pages and the total zone free pages is 247588. Discounting order-0 memory, there are only 59075 pages free with a min watermark of 875 pages. Discounting order-1 memory, there are 157 pages free with a min watermark of 437 pages. This is where your allocation fails. Even though the zone has 672KB of memory available, the per-order watermark fails. The only option you have to avoid this other than changing your workload is to alter lowmem_reserve_ratio, see Documentation/sysctl/vm.txt. You have 916KB of memory in ZONE_DMA that could be used for this allocation if it wasn't reserved for DMA allocations.