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From: Andrey Ryabinin <ryabinin.a.a@gmail.com>
To: Michal Hocko <mhocko@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Mika Westerberg <mika.westerberg@intel.com>,
	Hugh Dickins <hughd@google.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: mm related crash
Date: Mon, 14 Dec 2015 14:14:41 +0300	[thread overview]
Message-ID: <CAPAsAGxkYf0b_ZzhyuvxyNcWWvAyXHehGJbeGUAgu2Zb2u=31Q@mail.gmail.com> (raw)
In-Reply-To: <20151214105719.GA9544@dhcp22.suse.cz>

2015-12-14 13:57 GMT+03:00 Michal Hocko <mhocko@suse.cz>:
> On Mon 14-12-15 13:13:22, Andrey Ryabinin wrote:
>> 2015-12-14 13:05 GMT+03:00 Michal Hocko <mhocko@suse.cz>:
>> > On Mon 14-12-15 11:24:33, Kirill A. Shutemov wrote:
>> >> On Thu, Dec 10, 2015 at 05:48:01PM +0200, Mika Westerberg wrote:
>> >> > Hi Kirill,
>> >> >
>> >> > I got following crash on my desktop machine while building swift. It
>> >> > reproduces pretty easily on 4.4-rc4.
>> >> >
>> >> > Before it happens the ld process is killed by OOM killer. I attached the
>> >> > whole dmesg.
>> >> >
>> >> > [  254.740603] page:ffffea00111c31c0 count:2 mapcount:0 mapping:          (null) index:0x0
>> >> > [  254.740636] flags: 0x5fff8000048028(uptodate|lru|swapcache|swapbacked)
>> >> > [  254.740655] page dumped because: VM_BUG_ON_PAGE(!PageLocked(page))
>> >> > [  254.740679] ------------[ cut here ]------------
>> >> > [  254.740690] kernel BUG at mm/memcontrol.c:5270!
>> >>
>> >>
>> >> Hm. I don't see how this can happen.
>> >
>> > What a coincidence. I have just posted a similar report:
>> > http://lkml.kernel.org/r/20151214100156.GA4540@dhcp22.suse.cz except I
>> > have hit the VM_BUG_ON from a different path. My suspicion is that
>> > somebody unlocks the page while we are waiting on the writeback.
>> > I am trying to reproduce this now.
>>
>> Guys, this is fixed in rc5 - dfd01f026058a ("sched/wait: Fix the
>> signal handling fix").
>> http://lkml.kernel.org/r/<20151212162342.GF11257@ret.masoncoding.com>
>
> Hmm, so you think that some callpath was doing wait_on_page_locked and
> the above bug would allow a race and then unlock the page under our
> feet?

It rather more simple, read report carefully from the link I gave.
 __wait_on_bit_lock() in __lock_page() could just return  -EINTR and
leave the page unlocked.
So in rc4 lock_page() simply didn't work (sometimes).

> That would make some sense to me but I haven't checked the code to
> see which path that would be. I am also not able to reproduce this
> again...
> --
> Michal Hocko
> SUSE Labs

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  reply	other threads:[~2015-12-14 11:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20151210154801.GA12007@lahna.fi.intel.com>
2015-12-14  9:24 ` Kirill A. Shutemov
2015-12-14 10:05   ` Michal Hocko
2015-12-14 10:13     ` Andrey Ryabinin
2015-12-14 10:57       ` Michal Hocko
2015-12-14 11:14         ` Andrey Ryabinin [this message]
2015-12-14 11:54           ` Michal Hocko
2015-12-14 12:11       ` Mika Westerberg

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