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

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Message-ID: <20201106060414.edtcb7nrbzm4a32t@shindev.dhcp.fujisawa.hgst.com>
Date:   Fri, 6 Nov 2020 06:04:15 +0000
From:   Shinichiro Kawasaki <shinichiro.kawasaki@....com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Damien Le Moal <Damien.LeMoal@....com>
Subject: WARNING: can't access registers at asm_common_interrupt

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.

Wish this report helps.

[1] https://lkml.org/lkml/2020/9/6/231
[2] https://lkml.org/lkml/2020/9/8/1538

-- 
Best Regards,
Shin'ichiro Kawasaki