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From: Shakeel Butt To: Vlastimil Babka Cc: Carlos Maiolino , Venkat Rao Bagalkote , Johannes Weiner , Michal Hocko , Roman Gushchin , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, LKML , Madhavan Srinivasan , Ritesh Harjani , ojaswin@linux.ibm.com, Muchun Song , Cgroups , "linux-mm@kvack.org" , Harry Yoo , Hao Li Subject: Re: [next-20260216]NULL pointer dereference in drain_obj_stock() (RCU free path) Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Migadu-Flow: FLOW_OUT X-Stat-Signature: yshn7ywm3oggcod78r6u6f5gtow6yn87 X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 12DCA8000D X-HE-Tag: 1771449957-984085 X-HE-Meta: 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 KFgkWmC3 QuSh0x4mpBBEi4Him7+qgzxXnmyfcqiq2xAhHWM5CGt8Ol3Pn4E0UzAkCXsxFRibYcRfqTYnCs0V3k/IklJ1mG0z4hVwA9TISanFHaIfajneZKWt4/qW1reoLL0FeAAzHwMJ1Q18YPhivimIxiVE5yrMp3yYWpXDgQdlZN+Mc2KYE2yBoi6W3TN4ZsVkyrV264HSaq28IHifYTUAlHHIiLQdKrId+fhSd51H5oXulQZTkKVNp/FfMoK9Hb2t64971r8CqefM82ocAgOSPyNBVzSNGHbmb0vhk6QC12iMQdJbzuM4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Feb 18, 2026 at 12:36:06PM +0100, Vlastimil Babka wrote: > On 2/17/26 13:40, Carlos Maiolino wrote: > > On Tue, Feb 17, 2026 at 04:59:12PM +0530, Venkat Rao Bagalkote wrote: > >> Greetings!!! > >> > >> I am observing below OOPs, while running xfstests generic/428 test case. But > >> I am not able to reproduce this consistently. > >> > >> > >> Platform: IBM Power11 (pSeries LPAR), Radix MMU, LE, 64K pages > >> Kernel: 6.19.0-next-20260216 > >> Tests: generic/428 > >> > >> local.config >>> > >> [xfs_4k] > >> export RECREATE_TEST_DEV=true > >> export TEST_DEV=/dev/loop0 > >> export TEST_DIR=/mnt/test > >> export SCRATCH_DEV=/dev/loop1 > >> export SCRATCH_MNT=/mnt/scratch > >> export MKFS_OPTIONS="-b size=4096" > >> export FSTYP=xfs > >> export MOUNT_OPTIONS=""- > >> > >> > >> > >> Attached is .config file used. > >> > >> > >> Traces: > >> > > > > /me fixing trace's indentation > > CCing memcg and slab folks. > Would be nice to figure out where in drain_obj_stock things got wrong. Any > change for e.g. ./scripts/faddr2line ? > > I wonder if we have either some bogus objext pointer, or maybe the > rcu_free_sheaf() context is new (or previously rare) for memcg and we have > some locking issues being exposed in refill/drain. > Yes output of ./scripts/faddr2line would be really helpful. I can't think of anything that might go wrong in refill/drain.