Re: [Xen-devel] NFS related netback hang

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, Apr 11, 2013 at 02:55:48PM +0100, G.R. wrote:
> Hi,
> I'm suffering from strange NFS related network issue for a while.
> 
> The issue shows up when copying from dom0 to domU through a NFS mount.
> After a short while, the transfer suddenly freezes and the domU
> network simply stops any response. Force mounting the NFS mount
> generally resolves the freeze. But some times you can really be in
> bad luck that the trick does not work.
> 
> Lucky enough, I captured the following log in a recent instance. It
> appears to be a dead-lock when the netback tries to get some free
> pages from NFS. I'm not sure if this is the whole story. Any
> suggestion how to solve the issue?
> 

Unfortunately I cannot reproduce this at the moment. Please provide
detail configurations and steps.

I use NFS to test my netback / netfront patches, but I've never seen
anything like this. In my case I mostly export a dir in Dom0 then DomU
writes to it. Presumably in your case DomU exports a dir then Dom0
writes to it? I did simple test for both cases and couldn't see this
problem.


Wei.

> Thanks,
> Timothy
> 
> Apr 11 21:22:27 gaia kernel: [429242.015643] INFO: task netback/0:2255
> blocked for more than 120 seconds.
> Apr 11 21:22:27 gaia kernel: [429242.015665] "echo 0 >
> /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> Apr 11 21:22:27 gaia kernel: [429242.015690] netback/0       D
> ffff880210213900     0  2255      2 0x00000000
> Apr 11 21:22:27 gaia kernel: [429242.015693]  ffff8801fee04ea0
> 0000000000000246 0000000000000000 ffffffff818133f0
> Apr 11 21:22:27 gaia kernel: [429242.015697]  0000000000013900
> ffff8801fed87fd8 ffff8801fed87fd8 ffff8801fee04ea0
> Apr 11 21:22:27 gaia kernel: [429242.015700]  ffff8801fed87488
> ffff880210213900 ffff8801fee04ea0 ffff8801fed87488
> Apr 11 21:22:27 gaia kernel: [429242.015703] Call Trace:
> Apr 11 21:22:27 gaia kernel: [429242.015711]  [<ffffffff810c1bb5>] ?
> __lock_page+0x66/0x66
> Apr 11 21:22:27 gaia kernel: [429242.015715]  [<ffffffff814d06cb>] ?
> io_schedule+0x55/0x6b
> Apr 11 21:22:27 gaia kernel: [429242.015718]  [<ffffffff810c1bbc>] ?
> sleep_on_page+0x7/0xc
> Apr 11 21:22:27 gaia kernel: [429242.015720]  [<ffffffff814cf6c0>] ?
> __wait_on_bit_lock+0x3c/0x85
> Apr 11 21:22:27 gaia kernel: [429242.015723]  [<ffffffff810c3f7a>] ?
> find_get_pages+0xea/0x100
> Apr 11 21:22:27 gaia kernel: [429242.015726]  [<ffffffff810c1bb0>] ?
> __lock_page+0x61/0x66
> Apr 11 21:22:27 gaia kernel: [429242.015729]  [<ffffffff81058364>] ?
> autoremove_wake_function+0x2a/0x2a
> Apr 11 21:22:27 gaia kernel: [429242.015732]  [<ffffffff810cd110>] ?
> truncate_inode_pages_range+0x28b/0x2f8
> Apr 11 21:22:27 gaia kernel: [429242.015737]  [<ffffffff811c91d2>] ?
> nfs_evict_inode+0x12/0x23
> Apr 11 21:22:27 gaia kernel: [429242.015740]  [<ffffffff8111cdae>] ?
> evict+0xa3/0x153
> Apr 11 21:22:27 gaia kernel: [429242.015743]  [<ffffffff8111ce85>] ?
> dispose_list+0x27/0x31
> Apr 11 21:22:27 gaia kernel: [429242.015746]  [<ffffffff8111db6b>] ?
> evict_inodes+0xe7/0xf4
> Apr 11 21:22:27 gaia kernel: [429242.015749]  [<ffffffff8110b3af>] ?
> generic_shutdown_super+0x3e/0xc5
> Apr 11 21:22:27 gaia kernel: [429242.015752]  [<ffffffff8110b49e>] ?
> kill_anon_super+0x9/0x11
> Apr 11 21:22:27 gaia kernel: [429242.015755]  [<ffffffff811ca7b0>] ?
> nfs_kill_super+0xd/0x16
> Apr 11 21:22:27 gaia kernel: [429242.015758]  [<ffffffff8110b717>] ?
> deactivate_locked_super+0x2c/0x5c
> Apr 11 21:22:27 gaia kernel: [429242.015761]  [<ffffffff811c901d>] ?
> __put_nfs_open_context+0xbf/0xe1
> Apr 11 21:22:27 gaia kernel: [429242.015764]  [<ffffffff811d07db>] ?
> nfs_commitdata_release+0x10/0x19
> Apr 11 21:22:27 gaia kernel: [429242.015766]  [<ffffffff811d0f8c>] ?
> nfs_initiate_commit+0xd9/0xe4
> Apr 11 21:22:27 gaia kernel: [429242.015769]  [<ffffffff811d1bae>] ?
> nfs_commit_inode+0x81/0x111
> Apr 11 21:22:27 gaia kernel: [429242.015772]  [<ffffffff811c86f4>] ?
> nfs_release_page+0x40/0x4f
> Apr 11 21:22:27 gaia kernel: [429242.015775]  [<ffffffff810d0940>] ?
> shrink_page_list+0x4f5/0x6d8
> Apr 11 21:22:27 gaia kernel: [429242.015780]  [<ffffffff810d0f03>] ?
> shrink_inactive_list+0x1dd/0x33f
> Apr 11 21:22:27 gaia kernel: [429242.015783]  [<ffffffff810d15fa>] ?
> shrink_lruvec+0x2e0/0x44d
> Apr 11 21:22:27 gaia kernel: [429242.015787]  [<ffffffff810d17ba>] ?
> shrink_zone+0x53/0x8a
> Apr 11 21:22:27 gaia kernel: [429242.015790]  [<ffffffff810d1bcd>] ?
> do_try_to_free_pages+0x1c6/0x3f4
> Apr 11 21:22:27 gaia kernel: [429242.015794]  [<ffffffff810d20a3>] ?
> try_to_free_pages+0xc4/0x11e
> Apr 11 21:22:27 gaia kernel: [429242.015797]  [<ffffffff810c9018>] ?
> __alloc_pages_nodemask+0x440/0x72f
> Apr 11 21:22:27 gaia kernel: [429242.015801]  [<ffffffff810f592d>] ?
> alloc_pages_current+0xb2/0xcd
> Apr 11 21:22:27 gaia kernel: [429242.015805]  [<ffffffffa01be188>] ?
> xen_netbk_alloc_page.isra.17+0x15/0x4d [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015808]  [<ffffffffa01bf30c>] ?
> xen_netbk_tx_build_gops+0x3fc/0x7ab [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015812]  [<ffffffff812c0068>] ?
> pnp_show_options+0x43e/0x482
> Apr 11 21:22:27 gaia kernel: [429242.015816]  [<ffffffffa01beb3f>] ?
> xen_netbk_rx_action+0x688/0x6f8 [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015819]  [<ffffffff81061198>] ?
> finish_task_switch+0x4c/0x7c
> Apr 11 21:22:27 gaia kernel: [429242.015823]  [<ffffffffa01bf7e9>] ?
> xen_netbk_kthread+0x12e/0x790 [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015826]  [<ffffffff8105833a>] ?
> abort_exclusive_wait+0x79/0x79
> Apr 11 21:22:27 gaia kernel: [429242.015829]  [<ffffffffa01bf6bb>] ?
> xen_netbk_tx_build_gops+0x7ab/0x7ab [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015832]  [<ffffffffa01bf6bb>] ?
> xen_netbk_tx_build_gops+0x7ab/0x7ab [xen_netback]
> Apr 11 21:22:27 gaia kernel: [429242.015834]  [<ffffffff81057a31>] ?
> kthread+0x67/0x6f
> Apr 11 21:22:27 gaia kernel: [429242.015838]  [<ffffffff814d6904>] ?
> kernel_thread_helper+0x4/0x10
> Apr 11 21:22:27 gaia kernel: [429242.015841]  [<ffffffff814d143c>] ?
> retint_restore_args+0x5/0x6
> Apr 11 21:22:27 gaia kernel: [429242.015844]  [<ffffffff814d6900>] ?
> gs_change+0x13/0x13
> 
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