linux-kernel - Re: shrink_active_list/try_to_release_page bug? (was Re: xfs trace in 4.4.2 / also in 4.3.3 WARNING fs/xfs/xfs_aops.c:1232 xfs_vm

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Message-ID: <57502A2E.60702@applied-asynchrony.com>
Date:	Thu, 2 Jun 2016 14:44:30 +0200
From:	Holger Hoffstätte <holger@...lied-asynchrony.com>
To:	Stefan Priebe - Profihost AG <s.priebe@...fihost.ag>,
	Dave Chinner <david@...morbit.com>
Cc:	linux-mm@...ck.org, Minchan Kim <minchan@...nel.org>,
	Brian Foster <bfoster@...hat.com>,
	linux-kernel@...r.kernel.org, "xfs@....sgi.com" <xfs@....sgi.com>
Subject: Re: shrink_active_list/try_to_release_page bug? (was Re: xfs trace in
 4.4.2 / also in 4.3.3 WARNING fs/xfs/xfs_aops.c:1232 xfs_vm_releasepage)

On 06/02/16 14:13, Stefan Priebe - Profihost AG wrote:
> 
> Am 31.05.2016 um 09:31 schrieb Dave Chinner:
>> On Tue, May 31, 2016 at 08:11:42AM +0200, Stefan Priebe - Profihost AG wrote:
>>>> I'm half tempted at this point to mostly ignore this mm/ behavour
>>>> because we are moving down the path of removing buffer heads from
>>>> XFS. That will require us to do different things in ->releasepage
>>>> and so just skipping dirty pages in the XFS code is the best thing
>>>> to do....
>>>
>>> does this change anything i should test? Or is 4.6 still the way to go?
>>
>> Doesn't matter now - the warning will still be there on 4.6. I think
>> you can simply ignore it as the XFS code appears to be handling the
>> dirty page that is being passed to it correctly. We'll work out what
>> needs to be done to get rid of the warning for this case, wether it
>> be a mm/ change or an XFS change.
> 
> Any idea what i could do with 4.4.X? Can i safely remove the WARN_ONCE
> statement?

By definition it won't break anything since it's just a heads-up message,
so yes, it should be "safe". However if my understanding of the situation
is correct, mainline commit f0281a00fe "mm: workingset: only do workingset
activations on reads" (+ friends) in 4.7 should effectively prevent this
from happenning. Can someone confirm or deny this?

-h

PS: Stefan: I backported that commit (and friends) to my 4.4.x patch queue,
so if you want to try that for today's 4.4.12 the warning should be gone.
No guarantees though :)