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From: Vegard Nossum <vegard.nossum@gmail.com>
Date: Tue, 6 Dec 2016 09:42:05 +0100
Message-ID: <CAOMGZ=Gi3g_ALFRv-WiDaRT0pR5EN04OUzCtLX8mARp3_Gwv5A@mail.gmail.com>
Subject: Re: bio linked list corruption.
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>, Peter Zijlstra <peterz@infradead.org>,
        Dave Jones <davej@codemonkey.org.uk>, Chris Mason <clm@fb.com>,
        Jens Axboe <axboe@fb.com>, Andy Lutomirski <luto@amacapital.net>,
        Andy Lutomirski <luto@kernel.org>, Al Viro <viro@zeniv.linux.org.uk>,
        Josef Bacik <jbacik@fb.com>, David Sterba <dsterba@suse.com>,
        linux-btrfs <linux-btrfs@vger.kernel.org>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Dave Chinner <david@fromorbit.com>
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On 5 December 2016 at 22:33, Vegard Nossum <vegard.nossum@gmail.com> wrote:
> On 5 December 2016 at 21:35, Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
>> Note for Ingo and Peter: this patch has not been tested at all. But
>> Vegard did test an earlier patch of mine that just verified that yes,
>> the issue really was that wait queue entries remained on the wait
>> queue head just as we were about to return and free it.
>
> The second patch has been running for 1h+ without any problems of any
> kind. I should typically have seen 2 crashes by now. I'll let it run
> overnight to be sure.

Alright, so nearly 12 hours later I don't see either the new warning
or the original crash at all, so feel free to add:

Tested-by: Vegard Nossum <vegard.nossum@oracle.com>.

That said, my 8 VMs had all panicked in some way due to OOMs (which is
new since v4.8), although some got page allocation stalls for >20s and
died because "khugepaged blocked for more than 120 seconds", others
got "Out of memory and no killable processes".


Vegard