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Received: from 77-249-17-89.cable.dynamic.v4.ziggo.nl ([77.249.17.89] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1tNHv8-00000001vcF-2fiq; Mon, 16 Dec 2024 20:42:26 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 2D82830031E; Mon, 16 Dec 2024 21:42:24 +0100 (CET) Date: Mon, 16 Dec 2024 21:42:23 +0100 From: Peter Zijlstra To: Suren Baghdasaryan Cc: akpm@linux-foundation.org, willy@infradead.org, liam.howlett@oracle.com, 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 Subject: Re: [PATCH v6 10/16] mm: replace vm_lock and detached flag with a reference count Message-ID: <20241216204223.GA9803@noisy.programming.kicks-ass.net> References: <20241216192419.2970941-1-surenb@google.com> <20241216192419.2970941-11-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241216192419.2970941-11-surenb@google.com> X-Rspamd-Queue-Id: AD01A4000C X-Stat-Signature: omhybhh64nguhcr56jd6yi8ybap8wy9a X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1734381736-720006 X-HE-Meta: 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 hAnAkNJ3 /V7F12h++DDNE4cnP35ldEa6CHjrpunZY1SHqPxSu25nh5iSuVYNQJr+EF9ocP3fc1kx1HXzRNSs7a3qUWp4ZjVZs2EN+aDpUa8xC7Gmk5GybqdmBv19UAYS3gKWjpegFOXomkbxUMARgVcyzalXaEBK1Qyq6p6jNlffdugDZ0nXeD50eOvPsnK3gB02bYwodu4lIZ/zAeGUeTe6SS4N0JmZ4Ovmt3Y3ZLojdaj6fimYh8l5NJD9FV9AJ8A== 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, Dec 16, 2024 at 11:24:13AM -0800, Suren Baghdasaryan wrote: > @@ -734,10 +761,12 @@ static inline bool vma_start_read(struct vm_area_struct *vma) > * after it has been unlocked. > * This pairs with RELEASE semantics in vma_end_write_all(). > */ > + if (oldcnt & VMA_STATE_LOCKED || > + unlikely(vma->vm_lock_seq == raw_read_seqcount(&vma->vm_mm->mm_lock_seq))) { You likely want that unlikely to cover both conditions :-) > + vma_refcount_put(vma); > return false; > } > + > return true; > }