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Peter Anvin" , Alexei Starovoitov , Andrii Nakryiko , Arnd Bergmann , Boqun Feng , Daniel Borkman , Dinh Nguyen , Eduard Zingerman , Gary Guo , Guo Ren , Hao Luo , Jiri Olsa , John Fastabend , John Paul Adrian Glaubitz , Jonas Bonn , KP Singh , Marc Rutland , Martin KaFai Lau , Rich Felker , Song Liu , Stafford Horne , Stanislav Fomichev , Stefan Kristiansson , Will Deacon , Yonghong Song , Yoshinori Sato Subject: Re: [linus:master] [atomic] 80047d84ee: WARNING:at_include/linux/instrumented.h:#__split_huge_pmd_locked In-Reply-To: <202611022259.def3e086-lkp@intel.com> Message-ID: <13bdec81-18cb-4a1c-4932-41751346a621@linux-m68k.org> References: <202611022259.def3e086-lkp@intel.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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.