Re: general protection fault in finish_task_switch (2)

[Dmitry Vyukov]

On Wed, Aug 22, 2018 at 2:08 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Tue, Aug 21, 2018 at 02:28:02PM -0700, syzbot wrote:
>> syzbot has found a reproducer for the following crash on:
>>
>> HEAD commit:    778a33959a8a Merge tag 'please-pull-noboot' of git://git.k..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14a5385a400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=214e4990bd49329f
>> dashboard link: https://syzkaller.appspot.com/bug?extid=1f56df64bfb3c29dde6f
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> userspace arch: i386
>> syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13ffa561400000
>
> FWIW the lack of whitespace between "repro:" and the URL makes it hard
> to copy paste.

Fixed by:
https://github.com/google/syzkaller/commit/307deaee5e23e4585d4b408ebcf329b9dc8ebdb4
Thanks

>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10023961400000
>
>
>> RIP: 0010:__fire_sched_in_preempt_notifiers kernel/sched/core.c:2481
>
> That repro thing does something dodgy with KVM, which then corrupts the
> premption notifier thing. I'm sufficiently KVM clueless to not really
> know where to start looking though..