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bh=c4jFt5CSjdtnMDLvsXCu/fyC50qdW3CP98LJCVII0A8=; b=d5MjKKHwyjWRuUoQdFCQiQaKS/JlY/J94I3M2WBvbAmveiTWcDYJRvgsQn3QP1DbIS8h86 2MLS3tC4LCpGJZ/GhBlu/WwSnutZqfichRjG6EWfHMez2Ot67t008SDi5qbZV1Wnj5Iuop QqMNgkJvwaIxblG6TubYXrpPvSmURnY= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 7B41A139D2; Wed, 18 Jan 2023 09:23:38 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id EA6cHZq6x2NjNQAAMHmgww (envelope-from ); Wed, 18 Jan 2023 09:23:38 +0000 Date: Wed, 18 Jan 2023 10:23:34 +0100 From: Michal Hocko To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, michel@lespinasse.org, jglisse@google.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH 17/41] mm/mmap: move VMA locking before anon_vma_lock_write call Message-ID: References: <20230109205336.3665937-1-surenb@google.com> <20230109205336.3665937-18-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 1175920011 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: u6m4kgqeuikisewk5xko14kigz4w3wod X-HE-Tag: 1674033821-134344 X-HE-Meta: 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 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: On Tue 17-01-23 18:01:01, Suren Baghdasaryan wrote: > On Tue, Jan 17, 2023 at 7:16 AM Michal Hocko wrote: > > > > On Mon 09-01-23 12:53:12, Suren Baghdasaryan wrote: > > > Move VMA flag modification (which now implies VMA locking) before > > > anon_vma_lock_write to match the locking order of page fault handler. > > > > Does this changelog assumes per vma locking in the #PF? > > Hmm, you are right. Page fault handlers do not use per-vma locks yet > but the changelog already talks about that. Maybe I should change it > to simply: > ``` > Move VMA flag modification (which now implies VMA locking) before > vma_adjust_trans_huge() to ensure the modifications are done after VMA > has been locked. Because .... Withtout that additional reasonaning it is not really clear why that is needed and seems arbitrary. -- Michal Hocko SUSE Labs