Re: rpc_exit_task warning.

["J. Bruce Fields" <bfields@fieldses.org>]

On Tue, Jul 24, 2012 at 08:58:43PM +0200, Taylan Develioglu wrote:
> We just deployed a new nfs server and have about a hundred clients connected but are getting repeated kernel warnings on the server:

Did this replace an old server that didn't see these warnings?

> 
> Clients and servers run 3.2.18 and 3.2.20 respectively. We do not use any security options.
> 
> I don't really have time to debug this, but I felt I should report it.
> 
> - Client
>   ii  libevent-1.4-2                      1.4.13-stable-1
>   ii  util-linux                          2.17.2-9
>   ii  linux-image-3.2.0-0.bpo.2-amd64     3.2.18-1~bpo60+1
>   ii  nfs-common                          1:1.2.2-4squeeze2
> 
> - Server
>   ii  libevent-1.4-2                      1.4.13-stable-1
>   ii  util-linux                          2.17.2-9
>   ii  linux-image-3.2.0-0.bpo.2-amd64     3.2.20-1~bpo60+1
>   ii  libnfsidmap2                        0.24-1~bpo60+1               
>   ii  nfs-common                          1:1.2.5-4~bpo60+1            
>   ii  nfs-kernel-server                   1:1.2.5-4~bpo60+1            
> 
> exportfs -v
> /var/www/pictures
>                 x.x.x.x/22(rw,async,wdelay,root_squash,all_squash,no_subtree_check,anonuid=33,anongid=33)
> /var/www/pictures
>                 10.40.0.0/23(rw,async,wdelay,root_squash,all_squash,no_subtree_check,anonuid=33,anongid=33)
> 
> ----------------------------------------------------------------------------------------
> [ 1913.662849] WARNING: at /build/buildd-linux_3.2.20-1~bpo60+1-amd64-tQMw4f/linux-3.2.20/net/sunrpc/sched.c:630 rpc_exit_task+0x40/0x7a [sunrpc]()

That's a warning from rpc_task that both tk_action and RPC_TASK_KILLED
were set on exit from rpc_calL_done.

Couldn't that happen if there's a race between rpc_killall and
rpc_call_done trying to restart the task?  rpc_restart_call{_prepare}
check RPC_TASK_KILLED before setting the action, but does anything
prevent the flag being set after that check?

--b.

> [ 1913.662851] Hardware name: X8STi
> [ 1913.662852] Modules linked in: nfsd nfs lockd fscache auth_rpcgss nfs_acl sunrpc hmac drbd lru_cache cn ipmi_si ipmi_devintf ipmi_msghandler loop tpm_tis tpm parport_pc i2c_i801 i7core_edac i2c_core snd_pcm snd_timer snd ioatdma soundcore tpm_bios snd_page_alloc parport edac_core dca pcspkr psmouse processor serio_raw thermal_sys evdev joydev button ext4 mbcache jbd2 crc16 dm_mod sg sr_mod cdrom ses enclosure sd_mod crc_t10dif usb_storage usbhid hid uas uhci_hcd mptsas mptscsih mptbase scsi_transport_sas ahci libahci ehci_hcd libata usbcore aacraid usb_common scsi_mod e1000e [last unloaded: scsi_wait_scan]
> [ 1913.662902] Pid: 11, comm: kworker/0:1 Tainted: G        W    3.2.0-0.bpo.2-amd64 #1
> [ 1913.662904] Call Trace:
> [ 1913.662909]  [<ffffffff810498ac>] ? warn_slowpath_common+0x78/0x8c
> [ 1913.662916]  [<ffffffffa0327871>] ? rpc_exit_task+0x40/0x7a [sunrpc]
> [ 1913.662922]  [<ffffffffa0327ddb>] ? __rpc_execute+0x71/0x23f [sunrpc]
> [ 1913.662928]  [<ffffffffa0327fe1>] ? rpc_execute+0x38/0x38 [sunrpc]
> [ 1913.662981]  [<ffffffff8105f96c>] ? process_one_work+0x1cc/0x2ea
> [ 1913.662985]  [<ffffffff8105fbb7>] ? worker_thread+0x12d/0x247
> [ 1913.662987]  [<ffffffff8105fa8a>] ? process_one_work+0x2ea/0x2ea
> [ 1913.662990]  [<ffffffff8105fa8a>] ? process_one_work+0x2ea/0x2ea
> [ 1913.662993]  [<ffffffff810633c5>] ? kthread+0x7a/0x82
> [ 1913.662998]  [<ffffffff8136ca74>] ? kernel_thread_helper+0x4/0x10
> [ 1913.663000]  [<ffffffff8106334b>] ? kthread_worker_fn+0x147/0x147
> [ 1913.663003]  [<ffffffff8136ca70>] ? gs_change+0x13/0x13
> [ 1913.663005] ---[ end trace 7cee9f1fd80fe6ac ]---
> ----------------------------------------------------------------------------------------
> 
> Regards,
> 
> Taylan
> --
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