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AJvYcCXYSKdBgIELzZ/DJRTNehgcnPqkCNvdQUwvIkTeerSjGLVc7tGvO9uzaSngjdusHq4W7vJgj1/RJg==@kvack.org X-Gm-Message-State: AOJu0YxdHcJWcf2AiUpA9jh7I76xKKBBtMkagOyM+2t7D881ooDsNjIz O0fTVtl/fgaXUXJ1NTanhzczymCTQiYCzSL/M2F2BjA6lFzPmje2fJGtjxnKIc3v/sKHDkyZA0V SaAfGXIx2wR9ndgURnfgtRp+iE6yxqtOAkHro X-Gm-Gg: ASbGnct2WaJ41jBZs9ifWsQ/UYSMt7vSXHsBwa+R5ISNoXyvrm87F1SHWzIpQklKr6Z FSvMCjTB+JNriyOk+FrGruKPzPLf/cGCL7soJawO4nmenPhVxnCsme3MilQKJr0P5LyPNtRAJ8f 1KzT1qQQ7hAeG720bb X-Google-Smtp-Source: AGHT+IEn4udzSqij9W5TtY168fZ3ISFGTuwhi8IFIrEr1ddSwx4c84+jssbVKhdPt2W/Kzz4tpbpwatrQE4H4KrUWCg= X-Received: by 2002:a05:622a:6090:b0:467:82de:d949 with SMTP id d75a77b69052e-46e5c0f91a5mr4787321cf.12.1737654401102; Thu, 23 Jan 2025 09:46:41 -0800 (PST) MIME-Version: 1.0 References: <20240215182756.3448972-5-lokeshgidra@google.com> <20250123041427.1987-1-21cnbao@gmail.com> <6aee73c6-09aa-4c2a-a28e-af9532f3f66c@lucifer.local> <7a4f8c38-13a1-4a28-b7ce-ad3bb983dd69@redhat.com> In-Reply-To: <7a4f8c38-13a1-4a28-b7ce-ad3bb983dd69@redhat.com> From: Suren Baghdasaryan Date: Thu, 23 Jan 2025 09:46:30 -0800 X-Gm-Features: AbW1kva8LK6Oxl7iQk-wTWwjvZt1uKYq-oQd8CI-0vr3J2eS5f5rcXJCLlw0J98 Message-ID: Subject: Re: [PATCH v7 4/4] userfaultfd: use per-vma locks in userfaultfd operations To: David Hildenbrand Cc: Lorenzo Stoakes , Barry Song <21cnbao@gmail.com>, lokeshgidra@google.com, Liam.Howlett@oracle.com, aarcange@redhat.com, akpm@linux-foundation.org, axelrasmussen@google.com, bgeffon@google.com, jannh@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ngeoffray@google.com, peterx@redhat.com, rppt@kernel.org, ryan.roberts@arm.com, selinux@vger.kernel.org, timmurray@google.com, willy@infradead.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 43B8840014 X-Rspamd-Server: rspam10 X-Stat-Signature: e8yiwdewcurn69p43uu3d53o8h51mt8e X-HE-Tag: 1737654402-301895 X-HE-Meta: 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 shbQ7Zmy buSiw4towIV3igQPhjLbUW+W5jQL2FklCQmeaCO2FRiTGLdNkuXo9zEOeJYs+ibbTlrREfwcmXedTRCOlDFXJmzm4P70FgGHMaocVrSk5nmjnJpzjnLSus9zUDNlmHeU+TP1r2EXWfpFOzI4wVeZAOKOJk8FvwhN/Ltu++Dl9lzBidwP/nuP4MsarP+YTVZ/jy4nj5Ksu+t+c04Q8GSzXAJgcVjTLFW2rn3yV X-Bogosity: Ham, tests=bogofilter, spamicity=0.001596, 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 Thu, Jan 23, 2025 at 9:15=E2=80=AFAM David Hildenbrand wrote: > > >> > >> =E2=94=8C=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=90TASK_SIZE > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82mmap VOLATILE > >> =E2=94=BC=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=A4 > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82default mmap > >> =E2=94=82 =E2=94=82 > >> =E2=94=82 =E2=94=82 > >> =E2=94=94=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94= =80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=80=E2=94=98 > >> > >> VMAs in the volatile region are assigned their own volatile_mmap_lock, > >> which is independent of the mmap_lock for the non-volatile region. > >> Additionally, we ensure that no single VMA spans the boundary between > >> the volatile and non-volatile regions. This separation prevents the > >> frequent modifications of a small number of volatile VMAs from blockin= g > >> other operations on a large number of non-volatile VMAs. > > > > I think really overall this will be solving one can of worms by introdu= cing > > another can of very large worms in space :P but perhaps I am missing > > details here. > > Fully agreed; not a big fan :) +1. Let's not add more coarse-grained locks in mm. Discussing this at LSFMM as Liam suggested would be a good idea. I'm definitely interested. > > -- > Cheers, > > David / dhildenb >