mmots test error: WARNING in __wake_up_common

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syzbot

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Dec 1, 2017, 8:23:02 AM12/1/17
to linux-...@vger.kernel.org, mi...@redhat.com, pet...@infradead.org, syzkall...@googlegroups.com
Hello,

syzkaller hit the following crash on
11f44eb001da4c07b80055d8e24a0db4fb47eab1
git://git.cmpxchg.org/linux-mmots.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.

Unfortunately, I don't have any reproducer for this bug yet.


WARNING: CPU: 1 PID: 3084 at kernel/sched/wait.c:79
__wake_up_common+0x433/0x770 kernel/sched/wait.c:79
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 3084 Comm: syz-fuzzer Not tainted 4.15.0-rc1-mm1+ #32
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
panic+0x1e4/0x41c kernel/panic.c:183
__warn+0x1dc/0x200 kernel/panic.c:547
report_bug+0x211/0x2d0 lib/bug.c:184
fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:177
fixup_bug arch/x86/kernel/traps.c:246 [inline]
do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:295
do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:314
invalid_op+0x22/0x40 arch/x86/entry/entry_64.S:1066
RIP: 0010:__wake_up_common+0x433/0x770 kernel/sched/wait.c:79
RSP: 0018:ffff8801cb6874b0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff8801cc87e8d0 RCX: 0000000000000004
RDX: 1ffffffff0bd9741 RSI: ffff8801cc87e8e8 RDI: 0000000000000082
RBP: ffff8801cb6875b0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: ffffffff8748cda0 R12: 0000000000000000
R13: ffff8801cc87e910 R14: 0000000000000001 R15: ffff8801cc87e970
__wake_up_locked+0x11/0x20 kernel/sched/wait.c:160
ep_insert+0x15d0/0x1b10 fs/eventpoll.c:1495
SYSC_epoll_ctl fs/eventpoll.c:2106 [inline]
SyS_epoll_ctl+0x12e4/0x1ab0 fs/eventpoll.c:1992
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x45f7d8
RSP: 002b:000000c4203e5300 EFLAGS: 00000246 ORIG_RAX: 00000000000000e9
RAX: ffffffffffffffda RBX: 000000c42008c140 RCX: 000000000045f7d8
RDX: 0000000000000007 RSI: 0000000000000001 RDI: 0000000000000004
RBP: 000000c4203e56b8 R08: 0000000000000000 R09: 0000000000000000
R10: 000000c4203e532c R11: 0000000000000246 R12: 0000000000000000
R13: 00000000000000f2 R14: 0000000000000032 R15: 000000000000000f
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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config.txt
raw.log

Dmitry Vyukov

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Dec 1, 2017, 8:25:11 AM12/1/17
to syzbot, Christoph Hellwig, LKML, Ingo Molnar, Peter Zijlstra, syzkall...@googlegroups.com
On Fri, Dec 1, 2017 at 2:23 PM, syzbot
<bot+8a9655dff1b0463b1f...@syzkaller.appspotmail.com>
wrote:
I see there was a very recent commit in mm tree that touches this code:

commit f71569128519ba77d0bfb6a5a1f1c575804a2970
Author: Christoph Hellwig <h...@lst.de>
Date: Fri Dec 1 00:01:01 2017 +0000
epoll: use proper wake_up variant in ep_poll_callback

This was triggered when we just ssh into the instance.


> ---
> 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.
> Please credit me with: Reported-by: syzbot <syzk...@googlegroups.com>
>
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title
> 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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Christoph Hellwig

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Dec 1, 2017, 12:05:57 PM12/1/17
to Dmitry Vyukov, syzbot, Christoph Hellwig, LKML, Ingo Molnar, Peter Zijlstra, syzkall...@googlegroups.com
Ok, more epoll fun. We already have a discussion on it on lkml..

Dmitry Vyukov

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Dec 8, 2017, 1:05:24 PM12/8/17
to Christoph Hellwig, syzbot, LKML, Ingo Molnar, Peter Zijlstra, syzkall...@googlegroups.com
On Fri, Dec 1, 2017 at 6:05 PM, Christoph Hellwig <h...@lst.de> wrote:
> Ok, more epoll fun. We already have a discussion on it on lkml..

Need to tell the bot what fixed it:

#syz fix: epoll: use proper wake_up variant in ep_poll_callback

Dmitry Vyukov

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Dec 12, 2017, 9:01:04 AM12/12/17
to Christoph Hellwig, syzbot, LKML, Ingo Molnar, Peter Zijlstra, syzkall...@googlegroups.com
The right one seems to be:

#syz fix: epoll: use the waitqueue lock to protect ep->wq

Dmitry Vyukov

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Feb 13, 2018, 2:33:57 PM2/13/18
to syzbot, syzkall...@googlegroups.com
#syz fix: epoll: use the waitqueue lock to protect ep->wq

On Fri, Dec 1, 2017 at 2:23 PM, syzbot
<bot+8a9655dff1b0463b1f...@syzkaller.appspotmail.com>
wrote:

Dmitry Vyukov

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Feb 26, 2018, 4:28:15 AM2/26/18
to syzbot, syzkall...@googlegroups.com
It seems that this commit never made it anywhere:

#syz invalid
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