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Howlett" , Lorenzo Stoakes , Vlastimil Babka , Shakeel Butt , Jann Horn , Pedro Falcato , Chris Li Subject: [PATCH 0/2] vma_start_write_killable Date: Mon, 3 Nov 2025 18:03:44 +0000 Message-ID: <20251103180348.3368668-1-willy@infradead.org> X-Mailer: git-send-email 2.51.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: E86751A0017 X-Stat-Signature: s6c7uijbujr863ro9xqoce6bg4isnuo3 X-Rspam-User: X-HE-Tag: 1762193033-549749 X-HE-Meta: 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 bpaIfyjL HEh2vQPDVUlJOuNfNfJTMSnnF8IzHa09Fw8o+briAcLizvnkQjyB25AxMSKStrG+TBK9UHdTm8Scft08Q0dXgvQv3S3gnSN8YXKmYfsjFRDqqLkRc0xVmdQJmUPShmxphGzPuSUGJjnfHwaZ9FhXqWm/+9mzS0oLMLzYOHRJ1m4q5ts1Bm4j2GRKWn6nZBhPeYyhENgIzkKoUbiDcLD78pC2rQAV2wn2pP7Z9H9aLp69+hN3cereHlT8zew== 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: When we added the VMA lock, we made a major oversight in not adding a killable variant. That can run us into trouble where a thread takes the VMA lock for read (eg handling a page fault) and then goes out to lunch for an hour (eg doing reclaim). Another thread tries to modify the VMA, taking the mmap_lock for write, then attempts to lock the VMA for write. That blocks on the first thread, and ensures that every other page fault now tries to take the mmap_lock for read. Because everything's in an uninterruptible sleep, we can't kill the task, which makes me angry. This patch set just adds vma_start_write_killable() and converts one caller to use it. Most users are somewhat tricky to convert, so expect follow-up individual patches per call-site which need careful analysis to make sure we've done proper cleanup. Matthew Wilcox (Oracle) (2): mm: Add vma_start_write_killable() mm: Use vma_start_write_killable() in dup_mmap() include/linux/mmap_lock.h | 31 +++++++++++++++++++++++++++++-- mm/mmap.c | 12 +++--------- mm/mmap_lock.c | 27 ++++++++++++++++++--------- tools/testing/vma/vma_internal.h | 8 ++++++++ 4 files changed, 58 insertions(+), 20 deletions(-) -- 2.47.2