linux-kernel - Re: fs: locks: WARNING: CPU: 16 PID: 4296 at fs/locks.c:236 locks_free_lock

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Message-ID: <54B95426.5020509@oracle.com>
Date:	Fri, 16 Jan 2015 13:10:46 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Jeff Layton <jeff.layton@...marydata.com>
CC:	LKML <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: fs: locks: WARNING: CPU: 16 PID: 4296 at fs/locks.c:236 locks_free_lock_context+0x10d/0x240()

On 01/16/2015 09:40 AM, Jeff Layton wrote:
> On Fri, 16 Jan 2015 09:31:23 -0500
> Sasha Levin <sasha.levin@...cle.com> wrote:
> 
>> On 01/15/2015 03:22 PM, Jeff Layton wrote:
>>> Ok, I tried to reproduce it with that and several variations but it
>>> still doesn't seem to do it for me. Can you try the latest linux-next
>>> tree and see if it's still reproducible there?
>>
>> It's still not in in today's -next, could you send me a patch for testing
>> instead?
>>
> 
> Seems to be there for me:
> 
> ----------------------[snip]-----------------------
> /*
>  * This function is called on the last close of an open file.
>  */
> void locks_remove_file(struct file *filp)
> {
>         /* ensure that we see any assignment of i_flctx */
>         smp_rmb();
> 
>         /* remove any OFD locks */
>         locks_remove_posix(filp, filp);
> ----------------------[snip]-----------------------
> 
> That's actually the right place to put the barrier, I think. We just
> need to ensure that this function sees any assignment to i_flctx that
> occurred before this point. By the time we're here, we shouldn't be
> getting any new locks that matter to this close since the fcheck call
> should fail on any new requests.
> 
> If that works, then I'll probably make some other changes to the set
> and re-post it next week.
> 
> Many thanks for helping me test this!

You're right, I somehow missed that.

But it doesn't fix the issue, I still see it happening, but it seems
to be less frequent(?).


Thanks,
Sasha

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