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From: Dmitry Vyukov <dvyukov@google.com>
Date: Wed, 6 Dec 2017 16:54:17 +0100
Message-ID: <CACT4Y+ZZ2Wt0xAPVvQv0+k-PS=Ke2kerOnTeNKNUz5r+sanQvg@mail.gmail.com>
Subject: Re: general protection fault in lockdep_invariant_state (2)
To: Peter Zijlstra <peterz@infradead.org>
Cc: syzbot 
        <bot+2e39c7a45268c036c9e90433a48c9dd550276dc6@syzkaller.appspotmail.com>,
        LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@redhat.com>,
        syzkaller-bugs@googlegroups.com
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On Wed, Nov 29, 2017 at 1:00 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> On Mon, Nov 20, 2017 at 2:28 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>>>> > R13: 0000000000402260 R14: 00000000004022f0 R15: 0000000000000000
>>>> > kasan: CONFIG_KASAN_INLINE enabled
>>>> > kasan: GPF could be caused by NULL-ptr deref or user memory access
>>>> > general protection fault: 0000 [#1] SMP KASAN
>>>> > Dumping ftrace buffer:
>>>> >    (ftrace buffer empty)
>>>> > Modules linked in:
>>>> > CPU: 3 PID: 2982 Comm: syzkaller521009 Not tainted 4.14.0-rc7-next-20171103+
>>>> > #10
>>>> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>>>> > task: ffff88003d6b25c0 task.stack: ffff88003abd0000
>>>> > RIP: 0010:invalidate_xhlock kernel/locking/lockdep.c:4719 [inline]
>>>> > RIP: 0010:lockdep_invariant_state+0xd6/0x120 kernel/locking/lockdep.c:4793
>>>
>>>
>>> Does this help?
>>>
>>> diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
>>> index db933d063bfc..da2904418599 100644
>>> --- a/kernel/locking/lockdep.c
>>> +++ b/kernel/locking/lockdep.c
>>> @@ -4793,7 +4793,8 @@ void lockdep_invariant_state(bool force)
>>>          * Verify the former, enforce the latter.
>>>          */
>>>         WARN_ON_ONCE(!force && current->lockdep_depth);
>>> -       invalidate_xhlock(&xhlock(current->xhlock_idx));
>>> +       if (current->xhlocks)
>>> +               invalidate_xhlock(&xhlock(current->xhlock_idx));
>>>  }
>>>
>>>  static int cross_lock(struct lockdep_map *lock)
>>
>>
>> Hi Peter,
>>
>> We are not able to test all fixes for all bugs, but we are rolling out
>> a patch testing feature for syzbot:
>>
>> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
>>
>> Please give it a try!
>
>
> Peter, ping.
> This still happens. Please either submit the fix if you already tested
> it, or test using syzbot and submit.


Peter, do you want me to mail your patch?