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AJvYcCX0OH7hyNXjJO1DaP1c51VuzOQjaH7eE2gl3kXBNc4jBi7kuxW6NZ+AG/Sb72aHAd6ppRGhMTnSEw==@kvack.org X-Gm-Message-State: AOJu0YxRy0fiRVJS4th3kqXEuyl9plVv9qpdxA5pdF5l27GXLkyuJuPk OOD/XbWuL1GSVUxr6wiH0GX4kaLagZfmiUdUMbnePRvg6WJURdzWyLWKdPQCWkkZDy7nu67n7W2 sL2KLdlCL8BTRGjrHRh49n1TBqXC4XDc= X-Gm-Gg: ASbGncuALMlyJ7t6wSF3oJNznHPgf49ijVyDJyJK37PcXFR1LTd1hv96Plx2n+U56+g SFUMwWyRgKyeRC5n22GppFougXa2sxdTR88/ha8QAdMm9q2xGstaPPduObEbMwFA5gU0JIFm5E2 /jvpxGqirRMxI8IIr4mwf3/oz+4K8aij0cQ0qq1vnc5vU+LFbcmD+PW66e4BPOXNoH95qrfuT0m Jge/+7vdGrH4YxtzSvEchs= X-Google-Smtp-Source: AGHT+IHr1K/yJjlq6Ye1Sy8M8F+wQq/Rw7tGlOYrfGgCsGUOTDbj0Iu2trznQNcP3D2ebbnUU2V5lVrfGLyj6GAmXLg= X-Received: by 2002:a05:6a20:3944:b0:23f:fbb1:c21b with SMTP id adf61e73a8af0-24055046d01mr24530175637.17.1754954113102; Mon, 11 Aug 2025 16:15:13 -0700 (PDT) MIME-Version: 1.0 References: <20250808152850.2580887-1-surenb@google.com> <20250808152850.2580887-4-surenb@google.com> In-Reply-To: <20250808152850.2580887-4-surenb@google.com> From: Andrii Nakryiko Date: Mon, 11 Aug 2025 16:14:58 -0700 X-Gm-Features: Ac12FXwQt_eww5uvpy4ERMVpxcDuQGrIx4kEQc7H4eeLVmpPLimhRUNjaij0L4k Message-ID: Subject: Re: [PATCH v4 3/3] fs/proc/task_mmu: execute PROCMAP_QUERY ioctl under per-vma locks To: Suren Baghdasaryan Cc: 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, SeongJae Park Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 49A14180007 X-Rspamd-Server: rspam06 X-Stat-Signature: sy17yqtooohdj9j97afqwjopu9r58kse X-HE-Tag: 1754954114-43059 X-HE-Meta: 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 RWSvaGod vK6CcC/ZFXpxBeUXETxDJ0qQ49leRBQLr2MkssXsL+0jFssQHpd8YAjwQ9V/xjxEBkrtCTNtS5b5T49Pa1ZCmFV+moF7Sd0ClPIzJXr0BLXV6S1yWmiL9BCl8kF1LlQw5lekxUiW4XojCmViBq4t9iwfkyes3unqTtJWidpZCwBemMgd6vROdMOqFHigvQD3vbRMPBbGD9JAZvXW6IkJsECZFhcdcka+NkMqpzAQ387v7P1KESWNMP/Yf0eJiAKYBoBaOTPEMH688vCMnOuxoRAVDovqClVQV2TSYmbNPF5OLHlqwduK46vcCl57INy//gIdNnVD7bIkddyRcSCpWwWB6UUPzE6hv9MTjvI5O6wRZa9YKpJudaTztNl9omGRCvxm3Jp6J5p+F9WIx+89Rb5J+SKPttVnTIuT9i3lKh3PzSh4/K9i9VDA0slRIvoaWb3mrd9FaikEzeJKbK9mcI/X4ouBiJXUil0Ap3QIxUWSHPiw= 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 Fri, Aug 8, 2025 at 8:29=E2=80=AFAM 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 > --- > fs/proc/task_mmu.c | 103 +++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 85 insertions(+), 18 deletions(-) > LGTM Acked-by: Andrii Nakryiko [...]