Re: BUG: non-zero nr_pmds on freeing mm: 1

[Sedat Dilek <sedat.dilek@gmail.com>]

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On Mon, Feb 9, 2015 at 6:13 PM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
> On Mon, Feb 09, 2015 at 06:06:11PM +0100, Sedat Dilek wrote:
>> On Mon, Feb 9, 2015 at 5:42 PM, Kirill A. Shutemov <kirill@shutemov.name> wrote:
>> > On Sat, Feb 07, 2015 at 08:33:02AM +0100, Sedat Dilek wrote:
>> >> On Sat, Feb 7, 2015 at 6:12 AM, Pat Erley <pat-lkml@erley.org> wrote:
>> >> > I'm seeing the message in $subject on my Xen DOM0 on next-20150204 on
>> >> > x86_64.  I haven't had time to bisect it, but have seen some discussion on
>> >> > similar topics here recently.  I can trigger this pretty reliably by
>> >> > watching Netflix.  At some point (minutes to hours) into it, the netflix
>> >> > video goes black (audio keeps going, so it still thinks it's working) and
>> >> > the error appears in dmesg.  Refreshing the page gets the video going again,
>> >> > and it will continue playing for some indeterminate amount of time.
>> >> >
>> >> > Kirill, I've CC'd you as looking in the logs, you've patched a false
>> >> > positive trigger of this very recently(patch in kernel I'm running).  Am I
>> >> > actually hitting a problem, or is this another false positive case? Any
>> >> > additional details that might help?
>> >> >
>> >> > Dmesg from system attached.
>> >>
>> >> [ CC some mm folks ]
>> >>
>> >> I have seen this, too.
>> >>
>> >> root# grep "BUG: non-zero nr_pmds on freeing mm:" /var/log/kern.log | wc -l
>> >> 21
>> >>
>> >> Checking my logs: On next-20150203 and next-20150204.
>> >>
>> >> I am here not in a VM environment and cannot say what causes these messages.
>> >
>> > Sorry, my fault.
>> >
>> > The patch below should fix that.
>> >
>> > From 11bce596e653302e41f819435912f01ca8cbc27e Mon Sep 17 00:00:00 2001
>> > From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
>> > Date: Mon, 9 Feb 2015 18:34:56 +0200
>> > Subject: [PATCH] mm: fix race on pmd accounting
>> >
>> > Do not account the pmd table to the process if other thread allocated it
>> > under us.
>> >
>> > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
>> > Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
>>
>> Still building with the fix...
>>
>> Please feel free to add Pat as a reporter.
>>
>>      Reported-by: Pat Erley <pat-lkml@erley.org>
>>
>> Is that fixing...?
>>
>> commit daa1b0f29cdccae269123e7f8ae0348dbafdc3a7
>> "mm: account pmd page tables to the process"
>>
>> If yes, please add a Fixes-tag [2]...
>>
>>      Fixes: daa1b0f29cdc ("mm: account pmd page tables to the process")
>>
>> I will re-test with LTP/mmap and report.
>
> The commit is not in Linus tree, so the sha1-id is goinging to change.
>

OK, can you add a hint into the commit-message?
Thanks.

Tested-by: Sedat Dilek <sedat.dilek@gmail.com>

It looks like I triggered a new call-trace.

Regards,
- Sedat -

P.S.: List content of attached tarball

# LC_ALL=C ls -lR for-shutemov/
for-shutemov/:
total 452
-rw-r--r-- 1 root root   4312 Feb  9 17:57
3.19.0-rc7-next-20150204.17-iniza-small.patch
-rw-r--r-- 1 root root 125312 Feb  9 18:16
config-3.19.0-rc7-next-20150204.17-iniza-small
-rw-r--r-- 1 root root 120961 Feb  9 18:43
dmesg_3.19.0-rc7-next-20150204.17-iniza-small_after-ltp-mm.txt
-rw-r--r-- 1 root root  55056 Feb  9 18:25
dmesg_3.19.0-rc7-next-20150204.17-iniza-small_before-ltp-mm.txt
-rw-r--r-- 1 root root 141423 Feb  9 18:43
results-ltp_mm-testsuite_3.19.0-rc7-next-20150204.17-iniza-small.txt

- EOT -

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4ed23761a2dff77570425554ba98fc2d5c27ba0c050018f3db12e759cfc1cf14  for-shutemov.tar.gz