Bug#754354: Something holds dentry-related mutex forever in Wheezy amd64 kernel

[Mike Crowe <mac@mcrowe.com>]

On Monday 21 July 2014 at 15:01:31 +0100, Mike Crowe wrote:
> It is possible that I'm seeing the same problem. Our AMD Opteron 4386 (16
> cores) machine is also getting stuck with lots of hung tasks.

[snip]

> PID: 4087   TASK: ffff88040ea63840  CPU: 2   COMMAND: "nfsd"
>  #0 [ffff8804034b9c00] __schedule at ffffffff8134f195
>  #1 [ffff8804034b9c88] __mutex_lock_common.isra.5 at ffffffff8134fb74
>  #2 [ffff8804034b9cf8] mutex_lock at ffffffff8134fa62
>  #3 [ffff8804034b9d18] fh_lock_nested.isra.6 at ffffffffa043d63c [nfsd]
>  #4 [ffff8804034b9d28] nfsd_lookup_dentry at ffffffffa043df1a [nfsd]
>  #5 [ffff8804034b9d98] nfsd4_secinfo.part.15 at ffffffffa0447692 [nfsd]
>  #6 [ffff8804034b9dc8] nfsd4_proc_compound at ffffffffa04468d6 [nfsd]
>  #7 [ffff8804034b9e18] nfsd_dispatch at ffffffffa043a7cd [nfsd]
>  #8 [ffff8804034b9e48] svc_process_common at ffffffffa0336c3f [sunrpc]
>  #9 [ffff8804034b9eb8] svc_process at ffffffffa0337050 [sunrpc]
> #10 [ffff8804034b9ed8] nfsd at ffffffffa043a0e3 [nfsd]
> #11 [ffff8804034b9ef8] kthread at ffffffff8105f701
> #12 [ffff8804034b9f48] kernel_thread_helper at ffffffff813576f4

> ii  linux-image-amd64                            3.2+46
> ii  nfs-kernel-server                            1:1.2.6-4

That version information wasn't very useful, was it. :( I believe that this
crash was from linux-image-3.2.0-4-amd64 3.2.60-1+deb7u1

I've just had the same failure happen with 3.2.60-1+deb7u3.

Mike.