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[209.85.220.65]) by mx.google.com with SMTPS id r17sor1850922otg.84.2019.05.07.01.12.41 for (Google Transport Security); Tue, 07 May 2019 01:12:41 -0700 (PDT) Received-SPF: pass (google.com: domain of sultan.kerneltoast@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; spf=pass (google.com: domain of sultan.kerneltoast@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=sultan.kerneltoast@gmail.com X-Google-Smtp-Source: APXvYqxazZcvVgW8B8Abx61RE3d6GpWO8pSjTz4Bl2xHSbS/zPSIG/vaJXjunEVO9ubN+ITWd3WpFw== X-Received: by 2002:a9d:6d19:: with SMTP id o25mr3196049otp.151.1557216760884; Tue, 07 May 2019 01:12:40 -0700 (PDT) Received: from sultan-box.localdomain ([107.193.118.89]) by smtp.gmail.com with ESMTPSA id k60sm5643992otc.42.2019.05.07.01.12.38 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 07 May 2019 01:12:40 -0700 (PDT) Date: Tue, 7 May 2019 01:12:36 -0700 From: Sultan Alsawaf To: Greg Kroah-Hartman Cc: "open list:ANDROID DRIVERS" , Daniel Colascione , Todd Kjos , Kees Cook , Peter Zijlstra , Martijn Coenen , LKML , Tim Murray , Michal Hocko , Suren Baghdasaryan , linux-mm , Arve =?iso-8859-1?B?SGr4bm5lduVn?= , Ingo Molnar , Steven Rostedt , Oleg Nesterov , Joel Fernandes , Andy Lutomirski , kernel-team , Christian Brauner Subject: Re: [RFC] simple_lmk: Introduce Simple Low Memory Killer for Android Message-ID: <20190507081236.GA1531@sultan-box.localdomain> References: <20190318002949.mqknisgt7cmjmt7n@brauner.io> <20190318235052.GA65315@google.com> <20190319221415.baov7x6zoz7hvsno@brauner.io> <20190319231020.tdcttojlbmx57gke@brauner.io> <20190320015249.GC129907@google.com> <20190507021622.GA27300@sultan-box.localdomain> <20190507070430.GA24150@kroah.com> <20190507072721.GA4364@sultan-box.localdomain> <20190507074334.GB26478@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190507074334.GB26478@kroah.com> User-Agent: Mutt/1.11.4 (2019-03-13) 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, May 07, 2019 at 09:43:34AM +0200, Greg Kroah-Hartman wrote: > Given that any "new" android device that gets shipped "soon" should be > using 4.9.y or newer, is this a real issue? It's certainly a real issue for those who can't buy brand new Android devices without software bugs every six months :) > And if it is, I'm sure that asking for those patches to be backported to > 4.4.y would be just fine, have you asked? > > Note that I know of Android Go devices, running 3.18.y kernels, do NOT > use the in-kernel memory killer, but instead use the userspace solution > today. So trying to get another in-kernel memory killer solution added > anywhere seems quite odd. It's even more odd that although a userspace solution is touted as the proper way to go on LKML, almost no Android OEMs are using it, and even in that commit I linked in the previous message, Google made a rather large set of modifications to the supposedly-defunct lowmemorykiller.c not one month ago. What's going on? Qualcomm still uses lowmemorykiller.c [1] on the Snapdragon 845. If PSI were backported to 4.4, or even 3.18, would it really be used? I don't really understand the aversion to an in-kernel memory killer on LKML despite the rest of the industry's attraction to it. Perhaps there's some inherently great cost in using the userspace solution that I'm unaware of? Regardless, even if PSI were backported, a full-fledged LMKD using it has yet to be made, so it wouldn't be of much use now. Thanks, Sultan [1] https://source.codeaurora.org/quic/la/kernel/msm-4.9/tree/arch/arm64/configs/sdm845_defconfig?h=LA.UM.7.3.r1-07400-sdm845.0#n492