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Thu, 19 Dec 2024 08:09:04 -0800 (PST) MIME-Version: 1.0 References: <20241218100601.GI12500@noisy.programming.kicks-ass.net> <20241218161850.GG2354@noisy.programming.kicks-ass.net> <20241218174428.GQ2354@noisy.programming.kicks-ass.net> <20241219085515.GB26551@noisy.programming.kicks-ass.net> In-Reply-To: <20241219085515.GB26551@noisy.programming.kicks-ass.net> From: Suren Baghdasaryan Date: Thu, 19 Dec 2024 08:08:52 -0800 Message-ID: Subject: Re: [PATCH v6 10/16] mm: replace vm_lock and detached flag with a reference count To: Peter Zijlstra Cc: "Liam R. Howlett" , akpm@linux-foundation.org, willy@infradead.org, lorenzo.stoakes@oracle.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mjguzik@gmail.com, oliver.sang@intel.com, mgorman@techsingularity.net, david@redhat.com, peterx@redhat.com, oleg@redhat.com, dave@stgolabs.net, paulmck@kernel.org, brauner@kernel.org, dhowells@redhat.com, hdanton@sina.com, hughd@google.com, lokeshgidra@google.com, minchan@google.com, jannh@google.com, shakeel.butt@linux.dev, souravpanda@google.com, pasha.tatashin@soleen.com, klarasmodin@gmail.com, corbet@lwn.net, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@android.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: C785E18001A X-Stat-Signature: ryy37piz8eubp456sc7eo5niwegtms88 X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1734624511-629145 X-HE-Meta: U2FsdGVkX1/pc4Y0hzLErUu0yVjH92LT5cb+djrszQ0EEisg1SBEnW69GcXIsvqsB/6KX6kEQIRDudR4UZLIZlCa0pbnsqn/ZwpzVa7H1/AR7inu6D7/USZg2dVHpgpVNApFU2dBU7YCwTuRzveLHfqxrMW8MlE9BJao9mcPgHj7G6cBogxjQ0qhSgLnROMH9of11gZXkBo1L4b13oF5VBxdI5r53fGcH6+y1GKIr2HtNYQ2eZDUucEanWIKUI/Qw2NxQ3pnpNSBOJQpWpcV93K1viLkoW+58vjbUHjQUDQmWsH810EnCViEsUxri3bg9qmgft5X/JMZzI+1banyE8rEuU/cqqdVzEcwEgm5KWmENvxYBxTNlK23yV9FH4rzEIb2w3HoUOIuFdrJfop9QGKEWosK6HGI/WlHIMVUpFCJJrQftKTUbIUBgiI1ibskXxqxHZcLzvT3jdPrmWnSpPcrCK/k6zNntNKKko6EtTFzHVwBiMWPofzTpsClaGiaXilPl2KYJXyqMDcNP0eNTHPSF4PwVdu1G5tXnkyrElv7LTtTwv3/rO5C3iOScOSOfJPG/qhCzZ0T85oDbNXh/FOFUpt2dA79Dc3inh6IlrY0d3ufi+Ha7dyv6Wm/zN1JXdye3MHrq5bRo3aOBGXSaZwVPjvmsptkSrz03yjuNjW3tHL6qUAE9hHCo1o3fudRg7l2ZP5FuDfzktEvEwv6XIfJ62WmNBJNkA1ML/e9p94T1utBKRsWTXS9InZSDyBBGu2Cm8Djey62x8llXPW8j6Ggk462uyrUpnuessZNSrlN1QVp3LRXDmFLxAR1YW6rbuWD0VgomRJRPnTx+ykXuivfCwgEqKy4wLTfiTBC6Q/ylvhCOZJqq5w7GOGw2XNqSad6kKFjiok9enhZXYPAmSG94o2jlKEgbDWrrBMp5UzF9829I9ZpnIaulNtONIRKDlm+CGNYq4Ti+F0n6Y8 1i1P5E0h zGBQg+PXYIL/nAPxyDZKbQNay+zRrJ0EUzvKNYJzj5jhmP7qpradrmrDUravHaaJm+nFY8mzQ8/JaRRKPJKRQZiymVueBfs6OR6jPGUTYUHbxO34AuH2cDqBr6hIp4o9ztLEMEDAqt6zzKhDGRH8rNRJVgO22d0cdAHu3ardLHpkRxhaL1Lxl2RwdevlEisxKz/ebCySBbBBKK1z6qBWCI6QjXZSOHH98OllH3cGX0gcFyGT/rTKyTOnqnWbuWeb1i1HsZjIEV4IXwvc3nPFEdOCYEQYrhucERyx39Mzi16/KUFU= X-Bogosity: Unsure, tests=bogofilter, spamicity=0.478549, 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, Dec 19, 2024 at 12:55=E2=80=AFAM Peter Zijlstra wrote: > > On Wed, Dec 18, 2024 at 11:29:23AM -0800, Suren Baghdasaryan wrote: > > > Yeah, I think we can simply do this: > > > > vms_complete_munmap_vmas > > vms_clear_ptes > > remove_vma > > vma_mark_detached > > mmap_write_downgrade > > > > If my assumption is incorrect, assertion inside vma_mark_detached() > > should trigger. I tried a quick test and so far nothing exploded. > > I think that would be unfortunate and could cause regressions. I think > we want to keep vms_clear_ptes() under the read-lock. Ok, I'll stop considering this option.