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Thu, 20 Nov 2025 10:42:41 -0800 (PST) Received: from localhost ([2a03:2880:ff:a::]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7c3f024b7d2sm3456767b3a.40.2025.11.20.10.42.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Nov 2025 10:42:40 -0800 (PST) From: Joanne Koong To: akpm@linux-foundation.org Cc: david@redhat.com, linux-mm@kvack.org, shakeel.butt@linux.dev, athul.krishna.kr@protonmail.com, miklos@szeredi.hu, stable@vger.kernel.org Subject: [PATCH v1 0/2] mm: skip wait in wait_sb_inodes() for hangable-writeback mappings Date: Thu, 20 Nov 2025 10:42:09 -0800 Message-ID: <20251120184211.2379439-1-joannelkoong@gmail.com> X-Mailer: git-send-email 2.47.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 5AD074000F X-Stat-Signature: p9nxfj4p87whi36rtgx1oiqfffm84tsk X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1763664162-406032 X-HE-Meta: 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 Mm3sUBn8 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 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: As reported by Athul upstream in [1], there is a userspace regression caused by commit 0c58a97f919c ("fuse: remove tmp folio for writebacks and internal rb tree") where if there is a bug in a fuse server that causes the server to never complete writeback, it will make wait_sb_inodes() wait forever, causing sync paths to hang. This is a resubmission of this patch [2] that was dropped from the original series due to a buggy/malicious server still being able to hold up sync() / the system in other ways if they wanted to, but the wait_sb_inodes() path is particularly common and easier to hit for malfunctioning servers. Thanks, Joanne [1] https://lore.kernel.org/regressions/CAJnrk1ZjQ8W8NzojsvJPRXiv9TuYPNdj8Ye7=Cgkj=iV_i8EaA@mail.gmail.com/T/#t [2] https://lore.kernel.org/linux-fsdevel/20241122232359.429647-4-joannelkoong@gmail.com/ Joanne Koong (2): mm: rename AS_WRITEBACK_MAY_DEADLOCK_ON_RECLAIM to AS_WRITEBACK_MAY_HANG fs/writeback: skip inodes with potential writeback hang in wait_sb_inodes() fs/fs-writeback.c | 3 +++ fs/fuse/file.c | 2 +- include/linux/pagemap.h | 10 +++++----- mm/vmscan.c | 3 +-- 4 files changed, 10 insertions(+), 8 deletions(-) -- 2.47.3