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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uvixU-0000000Cyxf-2WaL; Mon, 08 Sep 2025 20:59:29 +0000 Date: Mon, 8 Sep 2025 21:59:28 +0100 From: Matthew Wilcox To: David Hildenbrand Cc: Anthony Yznaga , linux-mm@kvack.org, akpm@linux-foundation.org, andreyknvl@gmail.com, arnd@arndb.de, bp@alien8.de, brauner@kernel.org, bsegall@google.com, corbet@lwn.net, dave.hansen@linux.intel.com, dietmar.eggemann@arm.com, ebiederm@xmission.com, hpa@zytor.com, jakub.wartak@mailbox.org, jannh@google.com, juri.lelli@redhat.com, khalid@kernel.org, liam.howlett@oracle.com, linyongting@bytedance.com, lorenzo.stoakes@oracle.com, luto@kernel.org, markhemm@googlemail.com, maz@kernel.org, mhiramat@kernel.org, mgorman@suse.de, mhocko@suse.com, mingo@redhat.com, muchun.song@linux.dev, neilb@suse.de, osalvador@suse.de, pcc@google.com, peterz@infradead.org, pfalcato@suse.de, rostedt@goodmis.org, rppt@kernel.org, shakeel.butt@linux.dev, surenb@google.com, tglx@linutronix.de, vasily.averin@linux.dev, vbabka@suse.cz, vincent.guittot@linaro.org, viro@zeniv.linux.org.uk, vschneid@redhat.com, x86@kernel.org, xhao@linux.alibaba.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [PATCH v3 00/22] Add support for shared PTEs across processes Message-ID: References: <20250820010415.699353-1-anthony.yznaga@oracle.com> <5b7e71e8-4e31-4699-b656-c35dce678a80@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5b7e71e8-4e31-4699-b656-c35dce678a80@redhat.com> X-Stat-Signature: jwninj6winwgd3yjqxad48hyftf3sb4s X-Rspam-User: X-Rspamd-Queue-Id: 1AF9340002 X-Rspamd-Server: rspam04 X-HE-Tag: 1757365185-53786 X-HE-Meta: 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 IwXfB/p4 b2h9LvIe6DOhqrFzFm492rYTd8TqNMiDQRGz0Kqy8sTss4kXot5czfoKbvnKmgtbnVZWzUgL5MBRuRzDeJJk/2KBvgwY85WU6ZGN0NnRh35oyDtXFhs5YYJxIPR678xcOdMI2ugWxmpMu8FgFHgqInSSwd+ytaI3adrZimDvMLRgat7/G9uFsMHDwj3VxioGz8aImZ9YieoO6d2Q= 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 Mon, Sep 08, 2025 at 10:32:22PM +0200, David Hildenbrand wrote: > In the context of this series, how do we handle VMA-modifying functions like > mprotect/some madvise/mlock/mempolicy/...? Are they currently blocked when > applied to a mshare VMA? I haven't been following this series recently, so I'm not sure what Anthony will say. My expectation is that the shared VMA is somewhat transparent to these operations; that is they are faulty if they span the boundary of the mshare VMA, but otherwise they pass through and affect the shared VMAs. That does raise the interesting question of how mlockall() affects an mshare VMA. I'm tempted to say that it should affect the shared VMA, but reasonable people might well disagree with me and have excellent arguments. > And how are we handling other page table walkers that don't modify VMAs like > MADV_DONTNEED, smaps, migrate_pages, ... etc? I'd expect those to walk into the shared region too.