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b=d/y054IB3WTivroNoV2FuA+UveCHLltCgYNZqm23SCuo2K9wGbGR2ca6JyInOgSVe LYLjRM5pnbKC0QeVcHViZHHqT64AmrA7+rN4vgnhFxrEqyFoh23I1CaVCHNR80/chv +DuIUQynVIwoERpz8iCWEZg9uf1Nzr1Y2HH1TTNynQwuiRE2+hMbXXLE/j98m3NiCq INKjI9cpu4MAYIcc0N2+F4aHVyHz4y4h7OQdop9sNR0xVL7gnaINkSav9ExiAYebtU eivKoe6UotebTQfZDgo8QyQIrou2wX9HPTkpDlfL71wIAEzMUlsuOnJ0fwyvZXDGOq +rTtZl13re3PA== From: SeongJae Park To: Suren Baghdasaryan Cc: SeongJae Park , akpm@linux-foundation.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, david@redhat.com, vbabka@suse.cz, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, aha310510@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v3 3/3] fs/proc/task_mmu: execute PROCMAP_QUERY ioctl under per-vma locks Date: Wed, 6 Aug 2025 09:35:32 -0700 Message-Id: <20250806163532.82466-1-sj@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250806155905.824388-4-surenb@google.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4AE4040006 X-Rspam-User: X-Rspamd-Server: rspam09 X-Stat-Signature: 495zrkkpktjxnzwx5qsydtahqj7yc6ty X-HE-Tag: 1754498136-591877 X-HE-Meta: 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 L7rdKemK /Kr9P 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, 6 Aug 2025 08:59:04 -0700 Suren Baghdasaryan wrote: > Utilize per-vma locks to stabilize vma after lookup without taking > mmap_lock during PROCMAP_QUERY ioctl execution. If vma lock is > contended, we fall back to mmap_lock but take it only momentarily > to lock the vma and release the mmap_lock. In a very unlikely case > of vm_refcnt overflow, this fall back path will fail and ioctl is > done under mmap_lock protection. > > This change is designed to reduce mmap_lock contention and prevent > PROCMAP_QUERY ioctl calls from blocking address space updates. > > Signed-off-by: Suren Baghdasaryan Acked-by: SeongJae Park Thanks, SJ [...]