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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id z74sm2922006wmc.2.2019.05.21.00.06.39 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 21 May 2019 00:06:39 -0700 (PDT) Date: Tue, 21 May 2019 09:06:38 +0200 From: Oleksandr Natalenko To: Michal Hocko Cc: Minchan Kim , Andrew Morton , LKML , linux-mm , Johannes Weiner , Tim Murray , Joel Fernandes , Suren Baghdasaryan , Daniel Colascione , Shakeel Butt , Sonny Rao , Brian Geffon Subject: Re: [RFC 4/7] mm: factor out madvise's core functionality Message-ID: <20190521070638.yhn3w4lpohwcqbl3@butterfly.localdomain> References: <20190520035254.57579-1-minchan@kernel.org> <20190520035254.57579-5-minchan@kernel.org> <20190520142633.x5d27gk454qruc4o@butterfly.localdomain> <20190521012649.GE10039@google.com> <20190521063628.x2npirvs75jxjilx@butterfly.localdomain> <20190521065000.GH32329@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190521065000.GH32329@dhcp22.suse.cz> User-Agent: NeoMutt/20180716 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, May 21, 2019 at 08:50:00AM +0200, Michal Hocko wrote: > On Tue 21-05-19 08:36:28, Oleksandr Natalenko wrote: > [...] > > Regarding restricting the hints, I'm definitely interested in having > > remote MADV_MERGEABLE/MADV_UNMERGEABLE. But, OTOH, doing it via remote > > madvise() introduces another issue with traversing remote VMAs reliably. > > IIUC, one can do this via userspace by parsing [s]maps file only, which > > is not very consistent, and once some range is parsed, and then it is > > immediately gone, a wrong hint will be sent. > > > > Isn't this a problem we should worry about? > > See http://lkml.kernel.org/r/20190520091829.GY6836@dhcp22.suse.cz Oh, thanks for the pointer. Indeed, for my specific task with remote KSM I'd go with map_files instead. This doesn't solve the task completely in case of traversal through all the VMAs in one pass, but makes it easier comparing to a remote syscall. -- Best regards, Oleksandr Natalenko (post-factum) Senior Software Maintenance Engineer