linux-kernel - Re: x86: warning in unwind_get_return

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Date:   Tue, 27 Dec 2016 17:38:59 +0100
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Andrey Konovalov <andreyknvl@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Kostya Serebryany <kcc@...gle.com>
Subject: Re: x86: warning in unwind_get_return_address

On Thu, Dec 22, 2016 at 6:17 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> On Wed, Dec 21, 2016 at 01:46:36PM +0100, Andrey Konovalov wrote:
>> On Wed, Dec 21, 2016 at 12:36 AM, Josh Poimboeuf <jpoimboe@...hat.com> wrote:
>> >
>> > Thanks.  Looking at the stack trace, my guess is that an interrupt hit
>> > while running in generated BPF code, and the unwinder got confused
>> > because regs->ip points to the generated code.  I may need to disable
>> > that warning until we figure out a better solution.
>> >
>> > Can you share your .config file?
>>
>> Sure, attached.
>
> Ok, I was able to recreate with your config.  The culprit was generated
> code, as I suspected, though it wasn't BPF, it was a kprobe (created by
> dccpprobe_init()).
>
> I'll make a patch to disable the warning.

Hi,

I am also seeing the following warnings:

[  281.889259] WARNING: kernel stack regs at ffff8801c29a7ea8 in
syz-executor8:1302 has bad 'bp' value ffff8801c29a7f28
[  833.994878] WARNING: kernel stack regs at ffff8801c4e77ea8 in
syz-executor1:13094 has bad 'bp' value ffff8801c4e77f28

Can it also be caused by bpf/kprobe?