Ulrich Gemkow wrote:
Hello,
we have several error messages of nfsd on our fileserver which has 4 GB
RAM and has only a medium load (see below). The kernel is
vanilla 2.6.24.4.
These are in general scary warning messages that occurs when there is a
memory pressure and can be ignored most of the time. There is a
discussion going on LKML whether to ignore these message or not.
I would like to quote an LWN article[1] to provide further insight:
"In general, the kernel's memory allocator does not like to fail. So,
when kernel code requests memory, the memory management code will work
hard to satisfy the request. If this work involves pushing other pages
out to swap or removing data from the page cache, so be it. A big
exception happens, though, when an atomic allocation (using the
GFP_ATOMIC flag) is requested. Code requesting atomic allocations is
generally not in a position where it can wait around for a lot of memory
housecleaning work; in particular, such code cannot sleep. So if the
memory manager is unable to satisfy an atomic allocation with the memory
it has in hand, it has no choice except to fail the request."
Is there an explanation of these errors? The server seems to work
after these error messages.
In this case e1000_alloc_rx_buffers() calls __netdev_alloc_skb() with
GFP_ATOMIC and that explains the error message.
[1] - http://lwn.net/Articles/276731/
HTH,
====================
Apr 15 10:42:53 netsrv1 kernel: nfsd: page allocation failure. order:0, mode:0x20
Apr 15 10:42:53 netsrv1 kernel: Pid: 2474, comm: nfsd Not tainted 2.6.24-p2 #14
Apr 15 10:42:53 netsrv1 kernel: [<c0147605>] __alloc_pages+0x306/0x34c
Apr 15 10:42:53 netsrv1 kernel: [<c015d961>] cache_alloc_refill+0x2de/0x4ff
Apr 15 10:42:53 netsrv1 kernel: [<c015dc2b>] __kmalloc+0xa9/0xad
Apr 15 10:42:53 netsrv1 kernel: [<c03a89ab>] __alloc_skb+0x47/0xf6
Apr 15 10:42:53 netsrv1 kernel: [<c03a9515>] __netdev_alloc_skb+0x1c/0x37
Apr 15 10:42:53 netsrv1 kernel: [<c02b0176>] e1000_alloc_rx_buffers+0x176/0x37e
Apr 15 10:42:53 netsrv1 kernel: [<c01357d8>] getnstimeofday+0x2b/0xc3
Apr 15 10:42:53 netsrv1 kernel: [<c02b0b97>] e1000_clean_rx_irq+0x2a3/0x4bb
Apr 15 10:42:53 netsrv1 kernel: [<c02af343>] e1000_intr+0x61/0x121
Apr 15 10:42:53 netsrv1 kernel: [<c013fb39>] handle_IRQ_event+0x25/0x4a
Apr 15 10:42:53 netsrv1 kernel: [<c0140f20>] handle_fasteoi_irq+0x5f/0xb4
Apr 15 10:42:53 netsrv1 kernel: [<c0104fe7>] do_IRQ+0x3b/0x74
Apr 15 10:42:53 netsrv1 kernel: [<c01031f7>] common_interrupt+0x23/0x28
Apr 15 10:42:53 netsrv1 kernel: [<c0124482>] local_bh_enable_ip+0xe/0x44
Apr 15 10:42:53 netsrv1 kernel: [<c03fc0bf>] ipt_do_table+0x1f9/0x4be
Apr 15 10:42:53 netsrv1 kernel: [<c04022fe>] packet_rcv+0x2f/0x378
Apr 15 10:42:53 netsrv1 kernel: [<c03fc408>] ipt_local_hook+0x0/0x6f
Apr 15 10:42:53 netsrv1 kernel: [<c03bdaa6>] nf_iterate+0x56/0x7a
Apr 15 10:42:53 netsrv1 kernel: [<c03bdb3f>] nf_hook_slow+0x4d/0xbe
Apr 15 10:42:53 netsrv1 kernel: [<c03cde10>] dst_output+0x0/0x7
Apr 15 10:42:53 netsrv1 kernel: [<c03d0506>] ip_queue_xmit+0x27c/0x3ae
Apr 15 10:42:53 netsrv1 kernel: [<c03cde10>] dst_output+0x0/0x7
Apr 15 10:42:53 netsrv1 kernel: [<c03e519c>] tcp_v4_send_check+0x3b/0xc8
Apr 15 10:42:53 netsrv1 kernel: [<c03dfc41>] tcp_transmit_skb+0x3a8/0x730
Apr 15 10:42:53 netsrv1 kernel: [<c03a89ab>] __alloc_skb+0x47/0xf6
Apr 15 10:42:53 netsrv1 kernel: [<c03e012f>] tcp_send_ack+0xb6/0xf5
Apr 15 10:42:53 netsrv1 kernel: [<c03deddf>] tcp_rcv_established+0x3d8/0x719
Apr 15 10:42:53 netsrv1 kernel: [<c03e4890>] tcp_v4_do_rcv+0x94/0x359
Apr 15 10:42:53 netsrv1 kernel: [<c03fc3f3>] ipt_hook+0x0/0x15
Apr 15 10:42:53 netsrv1 kernel: [<c03fa175>] ipv4_conntrack_help+0x0/0x73
Apr 15 10:42:53 netsrv1 kernel: [<c03e6caf>] tcp_v4_rcv+0x75a/0x82b
Apr 15 10:42:53 netsrv1 kernel: [<c03cbc88>] ip_rcv+0x0/0x264
Apr 15 10:42:53 netsrv1 kernel: [<c03cbaf2>] ip_local_deliver_finish+0xc8/0x16b
Apr 15 10:42:53 netsrv1 kernel: [<c03cb7e8>] ip_rcv_finish+0xe8/0x32a
Apr 15 10:42:53 netsrv1 kernel: [<c03cbe6b>] ip_rcv+0x1e3/0x264
Apr 15 10:42:53 netsrv1 kernel: [<c03cb700>] ip_rcv_finish+0x0/0x32a
Apr 15 10:42:53 netsrv1 kernel: [<c03cbc88>] ip_rcv+0x0/0x264
Apr 15 10:42:53 netsrv1 kernel: [<c03ad11a>] netif_receive_skb+0x207/0x283
Apr 15 10:42:53 netsrv1 kernel: [<c04022cf>] packet_rcv+0x0/0x378
Apr 15 10:42:53 netsrv1 kernel: [<c03acf17>] netif_receive_skb+0x4/0x283
Apr 15 10:42:53 netsrv1 kernel: [<c04022cf>] packet_rcv+0x0/0x378
Apr 15 10:42:53 netsrv1 kernel: [<c03af619>] process_backlog+0x63/0xc4
Apr 15 10:42:53 netsrv1 kernel: [<c03af0b0>] net_rx_action+0x78/0x138
Apr 15 10:42:53 netsrv1 kernel: [<c03af3f8>] net_tx_action+0x43/0xe0
Apr 15 10:42:53 netsrv1 kernel: [<c0124282>] __do_softirq+0x72/0xdf
Apr 15 10:42:53 netsrv1 kernel: [<c0124326>] do_softirq+0x37/0x39
Apr 15 10:42:53 netsrv1 kernel: [<c01244b6>] local_bh_enable_ip+0x42/0x44
Apr 15 10:42:53 netsrv1 kernel: [<c04155b0>] svc_tcp_recvfrom+0x1ef/0x8fa
Apr 15 10:42:53 netsrv1 kernel: [<c01198e0>] update_curr+0x61/0xe5
Apr 15 10:42:53 netsrv1 kernel: [<c041f212>] schedule+0x1d0/0x669
Apr 15 10:42:53 netsrv1 kernel: [<c0127ae4>] try_to_del_timer_sync+0x47/0x4f
Apr 15 10:42:53 netsrv1 kernel: [<c0127afa>] del_timer_sync+0xe/0x15
Apr 15 10:42:53 netsrv1 kernel: [<c041f7ca>] schedule_timeout+0x4b/0xa1
Apr 15 10:42:53 netsrv1 kernel: [<c0414dde>] svc_recv+0x200/0x3f4
Apr 15 10:42:53 netsrv1 kernel: [<c011b1fb>] default_wake_function+0x0/0x8
Apr 15 10:42:53 netsrv1 kernel: [<c01e1223>] nfsd+0xc2/0x29f
Apr 15 10:42:53 netsrv1 kernel: [<c01e1161>] nfsd+0x0/0x29f
Apr 15 10:42:53 netsrv1 kernel: [<c0103437>] kernel_thread_helper+0x7/0x10
Apr 15 10:42:53 netsrv1 kernel: =======================
--
Suresh Jayaraman
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