From: Finn Thain <fthain@linux-m68k.org>
To: kernel test robot <yi1.lai@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: oe-lkp@lists.linux.dev, lkp@intel.com,
linux-kernel@vger.kernel.org,
Geert Uytterhoeven <geert@linux-m68k.org>,
Sasha Levin <sashal@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ard Biesheuvel <ardb@kernel.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
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Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
Will Deacon <will@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Yoshinori Sato <ysato@users.sourceforge.jp>
Subject: Re: [linus:master] [atomic] 80047d84ee: WARNING:at_include/linux/instrumented.h:#__split_huge_pmd_locked
Date: Tue, 3 Nov 2026 20:46:36 +1100 (AEDT) [thread overview]
Message-ID: <13bdec81-18cb-4a1c-4932-41751346a621@linux-m68k.org> (raw)
In-Reply-To: <202611022259.def3e086-lkp@intel.com>
On Tue, 3 Nov 2026, kernel test robot wrote:
>
> kernel test robot noticed "WARNING:at_include/linux/instrumented.h:#__split_huge_pmd_locked" on:
>
> commit: 80047d84eed25e9c92cfb9169980a0dfec110246 ("atomic: add alignment check to instrumented atomic operations") https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
>
It appears that a misaligned lock was accessed in
__split_huge_pmd_locked() back in 6.19.0-rc on i386.
And it appears that bisection landed on commit 80047d84eed2 ("atomic: add
alignment check to instrumented atomic operations") because that's when
the check got added to detect such accesses.
If the misaligned atomic operation is somehow normal in this situation (?)
then I guess it's a false positive from DEBUG_ATOMIC=y.
But if it was unintentional, the next step would probably be to check
whether the current mainline kernel has the same issue.
I have to confess to a state of ignorance about the mm subsystem so I
don't know what to conclude here.
next prev parent reply other threads:[~2026-11-03 9:46 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-03 0:58 kernel test robot
2026-11-03 9:46 ` Finn Thain [this message]
2026-11-03 12:18 ` Arnd Bergmann
2026-11-03 12:26 ` Peter Zijlstra
2026-11-03 12:35 ` Sasha Levin
2026-11-03 12:56 ` Peter Zijlstra
2026-11-03 13:13 ` Arnd Bergmann
2026-11-03 13:41 ` Arnd Bergmann
2026-11-03 14:52 ` Peter Zijlstra
2026-11-03 15:43 ` Andrew Morton
2026-11-03 15:58 ` David Hildenbrand (Arm)
2026-11-03 16:29 ` Dave Hansen
2026-11-03 16:51 ` Arnd Bergmann
2026-11-03 18:30 ` Dave Hansen
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