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b=NilYUMbbilI4RQjUGfcn58Vwrg+9D0LLpAdWCTgds7ae60PYotSnpJNzs6UKRkcEx 8WG5WAPCoYDTQM2B7hlX/vmX+j96zoGKAYoKsh9ehz8SmPtrrPgl0DSkQHc1crub1a 7hH3NkrzgEsnwv30WHxWhQ50m6D1dVkcIMBkqkIUIDS8nlfATsMzygomGgIkCNa1+p 7Dsv7LLkNpuN5AN/GVcoVMUTMUdeI5dEe0pzityoUCbm9Eufc/ppNCR0GQSBPEBNIw lsRs0y4VvPefoLW87NBvnT2cSTpXK5IZ0RuBz3CZ06dK7uoePZLpSFqlRCsVJ4BrN7 OoY1oqLq2RdzA== From: Sasha Levin To: shakeel.butt@linux.dev Cc: Sasha Levin , akpm@linux-foundation.org, baohua@kernel.org, cgroups@vger.kernel.org, chenxinxin@xiaomi.com, david@kernel.org, david@redhat.com, gregkh@linuxfoundation.org, hannes@cmpxchg.org, hughd@google.com, jose.fernandez@linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mambaxin@163.com, mhocko@kernel.org, muchun.song@linux.dev, roman.gushchin@linux.dev, ryncsn@gmail.com, shakeelb@google.com, stable@vger.kernel.org, syzbot+e12bd9ca48157add237a@syzkaller.appspotmail.com, v-songbaohua@oppo.com Subject: Re: [PATCH] mm: swap_cgroup: fix NULL deref in lookup_swap_cgroup_id on swapless host Date: Mon, 17 Aug 2026 11:24:42 -0400 Message-ID: <20260817150000.4@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260817032622.1135640-1-mambaxin@163.com> References: <20260817032622.1135640-1-mambaxin@163.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 0325EA0007 X-Stat-Signature: 4ykw5zat9njsbxbjximf148jiopo56by X-Rspam-User: X-HE-Tag: 1786980292-947499 X-HE-Meta: U2FsdGVkX197M5kxQsldiD84i6LbPKA3frUYQYhqjwy69W/YNPTrTB3ip9stpGz1OwQlNZOl5rX2C2RplobU0Lco0rheYaVJ18n0jxUIA8zWzD/OoQFRrPWlgh9PqP4LqADYVZm1Cu6o+gHO4Pe9Y0EJxJlD21II3fSV9oLJ5JgctQU82YwiggiYaaxRw8JsoZYNGhyU+zp4/te84dl0UAGI5LJCLBneNBrdKVyKO+YHnT8smbRh9s11oGbXiwsuHAYlCDmF3vItNvfNmjv3VCva9oT6h10KzxL95ZOrTqkRkcYG1EGxN4wiKShtQ0Qgniu3pcL3B1skeUBx5/johRiUw4mJmZ0IT0ZyPBNjJvZPSwynlxCZq793B8KivZUFZws1fYLudhXydQqnuDHpJfqPDIiwyxlaUEXt8C4JxKanUvWlLTf18dk+zjdwoErBCCh6xyhHjPFhg95ZavOuCKwEOZr8TMv890fs9/4/t+EVhXM5JFdhf732h1PvDpJL3j0pVX0F4COCBxN4oJHxVvnPF2LguYwcU5ToZCkS1Th/fiScxgHcK3gMLhvUy+leziDI1nBH2/1PX6ibTIhG8A+X108puPnjzhnOPpe7sTfBm1ZpWNKgPUlSEU8/TBhNMWWG7G6YSi6xveaDgOGcWv7tz8XTjT4aVOX4EpRzKipvBg2SJ1bVEJq7X7+OHZAu9HE+BnqqWYRXxpaKHFrNjCNyR7VLgdxz56vbhjhFNRhJzr32D7MSc4g2WLeM47dqU341qmPyEaZCK0hFM/lZnJO25zYBW6pWkqNEEOpgwifaQ2JGe5cF5JX3hfVFKi+LU4aqddJvIgIrH+3hVZMA4ruq/fHTSxPsMNXdw1gKB5vpKfLE0Gz/Cl7hlFJ0pBzNBMybvmwQPPNK8/0sJ5AahXTejenzO2MY60bftcOsRkfpb/VcVCdhnJg3nNil/bzljyU4pZeAF9/Q0HzXzMF zgdjv1s8 jnRiOn3uTjTty6JsFyKCCTGjqzIVvpAg2dJn2iNd25Rt/oHtDLs8qbPMAFSeDb5p5oLxvNmFz3lsNu/dfQ7jCBB9LBI1mKrZtE/i7oIKxpCR8HX5sNh8N6adHy4LVEkWNJHvtzhK09oyqXymkP40CSoxETB/D1q18gpNZ3/709hZrTrk/+Uhc7XeU0mrAqq0dycs2ZBuy8Oeju0ztV1s9iqEGfrGpmEILf/FiFkDXPETGZ/IRYpBrjrvhqK8Z+nLQ/iKzU5TT/CtAzzSV7QBtSIMChf1tK5A78lfQeav9TegtT+WeLnhvPdFSPMYE2nZhtOUYnpCfpY1cA2dRcXYNnq7vW3mbCXN3M1YVN3ChUiV+1UVBm3B6n5oTyY3J+N5n3l7/0PgbnvwAS7jy/NljROYNzIPW1FMKpHK5WFX18bs2JjbMhBPjBlhgEANKhUWx8AYA Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > Yes, we would like to backport this patch to the 6.6.y stable tree. > We have encountered the same issue on a product running the Android GKI 6.6 kernel. This is not a 6.6.y fix. The NULL deref is only reachable through the batching added by bea67dcc5eea ("mm: attempt to batch free swap entries for zap_pte_range()"), which is v6.12 and newer. 6.6.y has no swap_pte_batch() at all, so the exit_mmap -> zap_pte_range -> lookup_swap_cgroup_id path you are hitting does not exist there and the guard would be dead code. Your oops is on Android GKI 6.6, which carries the batching backport downstream - that is the tree that should carry this fix, alongside the commit that makes it reachable. -- Thanks, Sasha