BUG: Bad rss-counter state (3)

[syzbot]

Hello,

syzbot hit the following crash on upstream commit
a27fc14219f2e3c4a46ba9177b04d9b52c875532 (Mon Apr 16 21:07:39 2018 +0000)
Merge branch 'parisc-4.17-3' of
git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=f2a1633f249cece865fe

So far this crash happened 8 times on upstream.
C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6258099799195648
syzkaller reproducer:
https://syzkaller.appspot.com/x/repro.syz?id=5162423375888384
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4959118615904256
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-5914490758943236750
compiler: gcc (GCC) 8.0.1 20180413 (experimental)

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f2a163...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

BUG: Bad rss-counter state mm:00000000d5737ed7 idx:1 val:1
BUG: Bad rss-counter state mm:00000000d5737ed7 idx:3 val:-1


---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzk...@googlegroups.com.

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[Dmitry Vyukov]

On Thu, Apr 19, 2018 at 9:54 AM, syzbot
<syzbot+f2a163...@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot hit the following crash on upstream commit
> a27fc14219f2e3c4a46ba9177b04d9b52c875532 (Mon Apr 16 21:07:39 2018 +0000)
> Merge branch 'parisc-4.17-3' of
> git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
> syzbot dashboard link:
> https://syzkaller.appspot.com/bug?extid=f2a1633f249cece865fe
>
> So far this crash happened 8 times on upstream.
> C reproducer: https://syzkaller.appspot.com/x/repro.c?id=6258099799195648
> syzkaller reproducer:
> https://syzkaller.appspot.com/x/repro.syz?id=5162423375888384
> Raw console output:
> https://syzkaller.appspot.com/x/log.txt?id=4959118615904256
> Kernel config:
> https://syzkaller.appspot.com/x/.config?id=-5914490758943236750
> compiler: gcc (GCC) 8.0.1 20180413 (experimental)
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+f2a163...@syzkaller.appspotmail.com
> It will help syzbot understand when the bug is fixed. See footer for
> details.
> If you forward the report, please keep this part and the footer.

+mm maintainers (syzbot wasn't able to find maintainers because there
is no stack trace and no file names to give to get_maintainers.pl)

There is a single-threaded reproducer, so should be an easy one.

> BUG: Bad rss-counter state mm:00000000d5737ed7 idx:1 val:1
> BUG: Bad rss-counter state mm:00000000d5737ed7 idx:3 val:-1
>
>
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzk...@googlegroups.com.
>
> syzbot will keep track of this bug report.
> If you forgot to add the Reported-by tag, once the fix for this bug is
> merged
> into any tree, please reply to this email with:
> #syz fix: exact-commit-title
> If you want to test a patch for this bug, please reply with:
> #syz test: git://repo/address.git branch
> and provide the patch inline or as an attachment.
> To mark this as a duplicate of another syzbot report, please reply with:
> #syz dup: exact-subject-of-another-report
> If it's a one-off invalid bug report, please reply with:
> #syz invalid
> Note: if the crash happens again, it will cause creation of a new bug
> report.
> Note: all commands must start from beginning of the line in the email body.
>

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[syzbot]

syzbot suspects this bug was fixed by commit:

commit 173d9d9fd3ddae84c110fea8aedf1f26af6be9ec
Author: Hugh Dickins <hu...@google.com>
Date: Fri Nov 30 22:10:16 2018 +0000

mm/huge_memory: splitting set mapping+index before unfreeze

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=14202b7ae00000
start commit: a27fc142 Merge branch 'parisc-4.17-3' of git://git.kernel...
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=adeb81fdb5db9d72
dashboard link: https://syzkaller.appspot.com/bug?extid=f2a1633f249cece865fe
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1257325b800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=163bb567800000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: mm/huge_memory: splitting set mapping+index before unfreeze

For information about bisection process see: https://goo.gl/tpsmEJ#bisection