linux-kernel - Re: WARNING: can't access registers at asm_common

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Date:   Fri, 6 Nov 2020 12:06:28 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Shinichiro Kawasaki <shinichiro.kawasaki@....com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Damien Le Moal <Damien.LeMoal@....com>
Subject: Re: WARNING: can't access registers at asm_common_interrupt

On Fri, Nov 06, 2020 at 06:04:15AM +0000, Shinichiro Kawasaki wrote:
> Greetings,
> 
> I observe "WARNING: can't access registers at asm_common_interrupt+0x1e/0x40"
> in my kernel test system repeatedly, which is printed by unwind_next_frame() in
> "arch/x86/kernel/unwind_orc.c". Syzbot already reported that [1]. Similar
> warning was reported and discussed [2], but I suppose the cause is not yet
> clarified.
> 
> The warning was observed with v5.10-rc2 and older tags. I bisected and found
> that the commit 044d0d6de9f5 ("lockdep: Only trace IRQ edges") in v5.9-rc3
> triggered the warning. Reverting that from 5.10-rc2, the warning disappeared.
> May I ask comment by expertise on CC how this commit can relate to the warning?
> 
> The test condition to reproduce the warning is rather unique (blktests,
> dm-linear and ZNS device emulation by QEMU). If any action is suggested for
> further analysis, I'm willing to take it with my test system.

Hi,

Thanks for reporting this issue.  This might be a different issue from
[2].

Can you send me the arch/x86/entry/entry_64.o file from your build?

-- 
Josh