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Tue, 27 Oct 2026 15:47:37 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id +kHeCpnH4GpVXAAAD6G6ig (envelope-from ); Tue, 27 Oct 2026 15:47:37 +0000 Date: Tue, 27 Oct 2026 15:47:35 +0000 From: Pedro Falcato To: "David Hildenbrand (Arm)" Cc: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, Josef Bacik , stable@vger.kernel.org Subject: Re: [PATCH 06/46] mm/filemap: read mapping->a_ops->free_folio under i_lock Message-ID: References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> <20261027-fixes_core-v1-6-6f74bec9a5bb@kernel.org> 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 Content-Disposition: inline In-Reply-To: <20261027-fixes_core-v1-6-6f74bec9a5bb@kernel.org> X-Rspamd-Queue-Id: 3FCE01F456 X-Spam-Level: X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Flag: NO X-Spamd-Result: default: False [-12.01 / 50.00]; SUSE_INTERNAL_BYPASS(-9.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FREEMAIL_CC(0.00)[linux-foundation.org,cmpxchg.org,kernel.org,linux.dev,tencent.com,google.com,linux.alibaba.com,infradead.org,suse.com,soleen.com,suse.cz,nvidia.com,surriel.com,arm.com,intel.com,redhat.com,gmail.com,suse.de,huaweicloud.com,lge.com,gourry.net,sk.com,ziepe.ca,kvack.org,vger.kernel.org,lists.infradead.org,toxicpanda.com]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+]; FROM_HAS_DN(0.00)[]; MISSING_XM_UA(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; TO_DN_SOME(0.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received,2a07:de40:b281:104:10:150:64:97:from]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCPT_COUNT_GT_50(0.00)[65]; RCVD_VIA_SMTP_AUTH(0.00)[]; TAGGED_RCPT(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[toxicpanda.com:email,suse.de:dkim,imap1.dmz-prg2.suse.org:rdns,imap1.dmz-prg2.suse.org:helo] X-Spam-Score: -12.01 On Tue, Oct 27, 2026 at 12:17:26AM +0100, David Hildenbrand (Arm) wrote: > From: Josef Bacik > > memory_failure() -> ... -> filemap_remove_folio() can read mapping->a_ops > after the inode has been freed. Once the folio is deleted from the > pagecache it no longer pins the mapping, so after i_lock is dropped > e.g., a concurrent final iput() can evict and free the inode before > filemap_free_folio() looks up mapping->a_ops->free_folio. Ok, but after iput() then nothing also pins the filesystem, and thus the module. So we can be calling into total garbage. So what gives? You can't just take the pointer, you need to make sure the filesystem is also still alive. -- Pedro