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[37.188.174.195]) by smtp.gmail.com with ESMTPSA id w13sm13442356eju.124.2020.06.09.05.03.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2020 05:03:30 -0700 (PDT) Date: Tue, 9 Jun 2020 14:03:28 +0200 From: Michal Hocko To: Michel Lespinasse Cc: Andrew Morton , linux-mm , LKML , Peter Zijlstra , Laurent Dufour , Vlastimil Babka , Matthew Wilcox , Liam Howlett , Jerome Glisse , Davidlohr Bueso , David Rientjes , Hugh Dickins , Ying Han , Jason Gunthorpe , Daniel Jordan , John Hubbard Subject: Re: [PATCH v6 00/12] Add a new mmap locking API wrapping mmap_sem calls Message-ID: <20200609120328.GB22623@dhcp22.suse.cz> References: <20200520052908.204642-1-walken@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200520052908.204642-1-walken@google.com> X-Rspamd-Queue-Id: 71B04180192ED X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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: Hi, On Tue 19-05-20 22:28:56, Michel Lespinasse wrote: > Reposting this patch series on top of v5.7-rc6. I think this is ready > for inclusion into the -mm tree; however there were some minor points > of feedback to address and also it was easier to regenerate a full > version after the v5.5 (only updating patches 09/10 and 10/10) caused > some confusion. > > > This patch series adds a new mmap locking API replacing the existing > mmap_sem lock and unlocks. Initially the API is just implemente in terms > of inlined rwsem calls, so it doesn't provide any new functionality. > > There are two justifications for the new API: > > - At first, it provides an easy hooking point to instrument mmap_sem > locking latencies independently of any other rwsems. > > - In the future, it may be a starting point for replacing the rwsem > implementation with a different one, such as range locks. This is > something that is being explored, even though there is no wide concensus > about this possible direction yet. > (see https://patchwork.kernel.org/cover/11401483/) Sorry that I am jumping late to the game. Even though I hoped that the new API would somehow start using a concept of address ranges, because I believe this is a fundamental lock granularity for this mmap_sem, this is definitely a step in the right direction. Getting rid of all direct usage of mmap_sem is an improvement in itself. Feel free to add Acked-by: Michal Hocko Thanks! -- Michal Hocko SUSE Labs