Re: qemu-kvm hangs at start up under 3.8.0-rc3-00074-gb719f43 (works with CONFIG_LOCKDEP)

[Andrew Clayton <andrew@digital-domain.net>]

On Tue, 15 Jan 2013 17:17:56 +0000, Andrew Clayton wrote:

> On Tue, 15 Jan 2013 11:48:39 -0500, Rik van Riel wrote:
> 
> > On 01/14/2013 01:24 PM, Andrew Clayton wrote:
> 
> [snip]
> 
> > >
> > > bash            S ffff88013b2b0d00     0  3203   3133 0x00000000
> > >   ffff880114dabe58 0000000000000082 8000000113558065
> > > ffff880114dabfd8 ffff880114dabfd8 0000000000004000
> > > ffff88013b0c5b00 ffff88013b2b0d00 ffff880114dabd88
> > > ffffffff8109067d ffffea0004536670 ffffea0004536640 Call Trace:
> > >   [<ffffffff8109067d>] ? default_wake_function+0xd/0x10
> > >   [<ffffffff8108a315>] ? atomic_notifier_call_chain+0x15/0x20
> > >   [<ffffffff8133d84f>] ? tty_get_pgrp+0x3f/0x50
> > >   [<ffffffff810819ac>] ? pid_vnr+0x2c/0x30
> > >   [<ffffffff8133fe54>] ? tty_ioctl+0x7b4/0xbd0
> > >   [<ffffffff8106bf62>] ? wait_consider_task+0x102/0xaf0
> > >   [<ffffffff815c00e4>] schedule+0x24/0x70
> > >   [<ffffffff8106cb24>] do_wait+0x1d4/0x200
> > >   [<ffffffff8106d9cb>] sys_wait4+0x9b/0xf0
> > >   [<ffffffff8106b9f0>] ? task_stopped_code+0x50/0x50
> > >   [<ffffffff815c1ad2>] system_call_fastpath+0x16/0x1b
> > >
> > > qemu-kvm        D ffff88011ab8c8b8     0  3345   3203 0x00000000
> > >   ffff880112129cd8 0000000000000082 ffff880112129c50
> > > ffff880112129fd8 ffff880112129fd8 0000000000004000
> > > ffff88013b04ce00 ffff880139da1a00 0000000000000000
> > > 00000000000280da ffff880112129d38 ffffffff810d3300 Call Trace:
> > >   [<ffffffff810d3300>] ? __alloc_pages_nodemask+0xf0/0x7c0
> > >   [<ffffffff811273c6>] ? touch_atime+0x66/0x170
> > >   [<ffffffff810cdabf>] ? generic_file_aio_read+0x5bf/0x730
> > >   [<ffffffff815c00e4>] schedule+0x24/0x70
> > >   [<ffffffff815c0cdd>] rwsem_down_failed_common+0xbd/0x150
> > >   [<ffffffff815c0da3>] rwsem_down_write_failed+0x13/0x15
> > >   [<ffffffff812d1be3>] call_rwsem_down_write_failed+0x13/0x20
> > >   [<ffffffff815bf4dd>] ? down_write+0x2d/0x34
> > >   [<ffffffff810f0724>] vma_adjust+0xe4/0x610
> > >   [<ffffffff810f0fa4>] vma_merge+0x1b4/0x270
> > >   [<ffffffff810f1fa6>] do_brk+0x196/0x330
> > >   [<ffffffff810f2217>] sys_brk+0xd7/0x130
> > >   [<ffffffff815c1ad2>] system_call_fastpath+0x16/0x1b
> > 
> > This looks like qemu-kvm getting stuck trying to get the anon_vma
> > lock.
> > 
> > That leads to the obvious question: what is holding the lock, and/or
> > failed to release it?
> > 
> > Do you have any other (qemu-kvm?) processes on your system that have
> > any code in the VM (or strace/ptrace/...) in the backtrace, that
> > might be holding this lock?
> 
> I don't think so. The above was done having just logged into
> gnome-shell and opened up a couple of gnome-terminals.
>  
> > Do you have anything in your dmesg showing threads that had a BUG_ON
> > (and exited) while holding the lock?
> 
> I never noticed anything like that.
> 
> The interesting thing is that if I use basically the same kernel but
> with CONFIG_LOCKDEP enabled, it works fine.
> 
> Hmm, I wonder if it's the same as this?
> http://lkml.indiana.edu/hypermail/linux/kernel/1301.1/02810.html
> 
> When I get home, I'll try a kernel with those two patches reverted.
> They seem to be
> 
> 572043c90db65b45a4efd959db7458edcf6411ad
> 1b963c81b14509e330e0fe3218b645ece2738dc5

Just checked the issue is still there in Linus' latest,
3.8.0-rc3-00293-g406089d, it is.

However, building a kernel with those two commits reverted does indeed
get it going again.

Andrew