Re: WARNING in rcu_note_context_switch

From: Peter Zijlstra
Date: Tue Oct 01 2019 - 04:45:28 EST


On Tue, Oct 01, 2019 at 01:09:07AM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit: 54ecb8f7 Linux 5.4-rc1
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=14972bf3600000
> kernel config: https://syzkaller.appspot.com/x/.config?x=fb0b431ccdf08c1c
> dashboard link: https://syzkaller.appspot.com/bug?extid=0e1a9dce275f13907b4e
> compiler: clang version 9.0.0 (/home/glider/llvm/clang
> 80fee25776c2fb61e74c1ecb1a523375c2500b69)
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16875a35600000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=104bd519600000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+0e1a9dce275f13907b4e@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 7994 at kernel/rcu/tree_plugin.h:293
> rcu_note_context_switch+0xdde/0xee0 kernel/rcu/tree_plugin.h:293
> Kernel panic - not syncing: panic_on_warn set ...

https://lkml.kernel.org/r/20191001071921.GJ4519@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx