Re: next-20130117 - kernel BUG with aio

[Valdis.Kletnieks@vt.edu]

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On Tue, 22 Jan 2013 21:43:27 +0800, Hillf Danton said:
> On Mon, Jan 21, 2013 at 9:24 PM, Valdis Kletnieks
> <Valdis.Kletnieks@vt.edu> wrote:
> > Am seeing a reproducible BUG in the kernel with next-20130117
> > whenever I fire up VirtualBox.  Unfortunately, I hadn't done that
> > in a while, so the last 'known good' kernel was next-20121203.
> >
> > I'm strongly suspecting one of Kent Overstreet's 32 patches against aio,
> > because 'git blame' shows those landing on Jan 12, and not much else
> > happening to fs/aio.c in ages.
> >
> Take a try?
> ---
> --- a/fs/aio.c	Tue Jan 22 21:37:54 2013
> +++ b/fs/aio.c	Tue Jan 22 21:43:58 2013
> @@ -683,6 +683,9 @@ static inline void kioctx_ring_unlock(st
>  {
>  	struct aio_ring *ring;
>
> +	if (!ctx)
> +		return;
> +
>  	smp_wmb();
>  	/* make event visible before updating tail */

Well, things are improved - at least now it doesn't BUG :)

[  534.879083] ------------[ cut here ]------------
[  534.879094] WARNING: at fs/aio.c:336 put_ioctx+0x1cb/0x252()
[  534.879121] Call Trace:
[  534.879129]  [<ffffffff8102f5ad>] warn_slowpath_common+0x7e/0x97
[  534.879133]  [<ffffffff8102f5db>] warn_slowpath_null+0x15/0x17
[  534.879137]  [<ffffffff811521f0>] put_ioctx+0x1cb/0x252
[  534.879142]  [<ffffffff8105bee3>] ? __wake_up+0x3f/0x48
[  534.879146]  [<ffffffff8115229e>] ? kill_ioctx_work+0x27/0x2b
[  534.879150]  [<ffffffff811531a5>] sys_io_destroy+0x40/0x50
[  534.879156]  [<ffffffff8161b112>] system_call_fastpath+0x16/0x1b
[  534.879159] ---[ end trace a2c46a8bc9058404 ]---

Hopefully that tells you and Kent something. :)

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