kernel: page allocation failure.

Jun 19 04:18:24 p172295 kernel: nginx: page allocation failure. order:1, mode:0x20
Jun 19 04:18:24 p172295 kernel: Pid: 32371, comm: nginx Not tainted 2.6.32-358.2.1.el6.x86_64 #1
Jun 19 04:18:24 p172295 kernel: Call Trace:
Jun 19 04:18:24 p172295 kernel: <IRQ>  [<ffffffff8112c207>] ? __alloc_pages_nodemask+0x757/0x8d0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8105230c>] ? check_preempt_curr+0x7c/0x90
Jun 19 04:18:24 p172295 kernel: [<ffffffff8144d1ff>] ? netif_rx+0xaf/0x160
Jun 19 04:18:24 p172295 kernel: [<ffffffff81166ab2>] ? kmem_getpages+0x62/0x170
Jun 19 04:18:24 p172295 kernel: [<ffffffff811676ca>] ? fallback_alloc+0x1ba/0x270
Jun 19 04:18:24 p172295 kernel: [<ffffffff8116711f>] ? cache_grow+0x2cf/0x320
Jun 19 04:18:24 p172295 kernel: [<ffffffff81167449>] ? ____cache_alloc_node+0x99/0x160
Jun 19 04:18:24 p172295 kernel: [<ffffffff811683cb>] ? kmem_cache_alloc+0x11b/0x190
Jun 19 04:18:24 p172295 kernel: [<ffffffff81439d58>] ? sk_prot_alloc+0x48/0x1c0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8143ae32>] ? sk_clone+0x22/0x2e0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81489d66>] ? inet_csk_clone+0x16/0xd0
Jun 19 04:18:24 p172295 kernel: [<ffffffff814a2c73>] ? tcp_create_openreq_child+0x23/0x450
Jun 19 04:18:24 p172295 kernel: [<ffffffff814a046d>] ? tcp_v4_syn_recv_sock+0x4d/0x310
Jun 19 04:18:24 p172295 kernel: [<ffffffff814a2a16>] ? tcp_check_req+0x226/0x460
Jun 19 04:18:24 p172295 kernel: [<ffffffff8149ff0b>] ? tcp_v4_do_rcv+0x35b/0x430
Jun 19 04:18:24 p172295 kernel: [<ffffffffa017f557>] ? ipv4_confirm+0x87/0x1d0 [nf_conntrack_ipv4]
Jun 19 04:18:24 p172295 kernel: [<ffffffff814a171e>] ? tcp_v4_rcv+0x4fe/0x8d0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8147f430>] ? ip_local_deliver_finish+0x0/0x2d0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8147f50d>] ? ip_local_deliver_finish+0xdd/0x2d0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8147f798>] ? ip_local_deliver+0x98/0xa0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8147ec5d>] ? ip_rcv_finish+0x12d/0x440
Jun 19 04:18:24 p172295 kernel: [<ffffffff8147f1e5>] ? ip_rcv+0x275/0x350
Jun 19 04:18:24 p172295 kernel: [<ffffffff814483bb>] ? __netif_receive_skb+0x4ab/0x750
Jun 19 04:18:24 p172295 kernel: [<ffffffff814486fa>] ? process_backlog+0x9a/0x100
Jun 19 04:18:24 p172295 kernel: [<ffffffff8144cf63>] ? net_rx_action+0x103/0x2f0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81076fb1>] ? __do_softirq+0xc1/0x1e0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8100c1cc>] ? call_softirq+0x1c/0x30
Jun 19 04:18:24 p172295 kernel: <EOI>  [<ffffffff8100de05>] ? do_softirq+0x65/0xa0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81076e3a>] ? local_bh_enable+0x9a/0xb0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8144c98c>] ? dev_queue_xmit+0x16c/0x550
Jun 19 04:18:24 p172295 kernel: [<ffffffff814851c0>] ? ip_finish_output+0x0/0x310
Jun 19 04:18:24 p172295 kernel: [<ffffffff814852fc>] ? ip_finish_output+0x13c/0x310
Jun 19 04:18:24 p172295 kernel: [<ffffffff81485588>] ? ip_output+0xb8/0xc0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8148484f>] ? __ip_local_out+0x9f/0xb0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81484885>] ? ip_local_out+0x25/0x30
Jun 19 04:18:24 p172295 kernel: [<ffffffff81484d60>] ? ip_queue_xmit+0x190/0x420
Jun 19 04:18:24 p172295 kernel: [<ffffffff81499a4e>] ? tcp_transmit_skb+0x3fe/0x7b0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8149be0b>] ? tcp_write_xmit+0x1fb/0xa20
Jun 19 04:18:24 p172295 kernel: [<ffffffff8149c7c0>] ? __tcp_push_pending_frames+0x30/0xe0
Jun 19 04:18:24 p172295 kernel: [<ffffffff8148c03e>] ? tcp_push+0x6e/0x90
Jun 19 04:18:24 p172295 kernel: [<ffffffff8148d03c>] ? tcp_sendmsg+0x64c/0xa20
Jun 19 04:18:24 p172295 kernel: [<ffffffff81437dbb>] ? sock_aio_write+0x19b/0x1c0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81437c20>] ? sock_aio_write+0x0/0x1c0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81180c3b>] ? do_sync_readv_writev+0xfb/0x140
Jun 19 04:18:24 p172295 kernel: [<ffffffff81498d0c>] ? tcp_rcv_state_process+0x9fc/0xa10
Jun 19 04:18:24 p172295 kernel: [<ffffffff81096ca0>] ? autoremove_wake_function+0x0/0x40
Jun 19 04:18:24 p172295 kernel: [<ffffffff8121bc06>] ? security_file_permission+0x16/0x20
Jun 19 04:18:24 p172295 kernel: [<ffffffff81181bc6>] ? do_readv_writev+0xd6/0x1f0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81436447>] ? sys_connect+0xd7/0xf0
Jun 19 04:18:24 p172295 kernel: [<ffffffff81181d26>] ? vfs_writev+0x46/0x60
Jun 19 04:18:24 p172295 kernel: [<ffffffff81181e51>] ? sys_writev+0x51/0xb0
Jun 19 04:18:24 p172295 kernel: [<ffffffff810dc645>] ? __audit_syscall_exit+0x265/0x290
Jun 19 04:18:24 p172295 kernel: [<ffffffff8100b072>] ? system_call_fastpath+0x16/0x1b

uname -a
Linux 2.6.32-358.2.1.el6.x86_64 #1 SMP Wed Mar 13 00:26:49 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

free
             total       used       free     shared    buffers     cached
Mem:      12188420   10455836    1732584          0    1343600    6290124
-/+ buffers/cache:    2822112    9366308
Swap:      8393848     102152    8291696