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Wed, 25 Mar 2020 11:23:39 -0700 (PDT) Received: from avx2 ([46.53.251.45]) by smtp.gmail.com with ESMTPSA id m3sm4298649wmm.3.2020.03.25.11.23.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 11:23:39 -0700 (PDT) Date: Wed, 25 Mar 2020 21:23:36 +0300 From: Alexey Dobriyan To: Greg KH Cc: Jaewon Kim , leon@kernel.org, vbabka@suse.cz, akpm@linux-foundation.org, labbott@redhat.com, sumit.semwal@linaro.org, minchan@kernel.org, ngupta@vflare.org, sergey.senozhatsky.work@gmail.com, kasong@redhat.com, bhe@redhat.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaewon31.kim@gmail.com, linux-api@vger.kernel.org, kexec@lists.infradead.org Subject: Re: [RFC PATCH v2 1/3] meminfo_extra: introduce meminfo extra Message-ID: <20200325182336.GC18706@avx2> References: <20200323080503.6224-1-jaewon31.kim@samsung.com> <20200323080503.6224-2-jaewon31.kim@samsung.com> <20200323095344.GB425358@kroah.com> <5E79CEB5.8070308@samsung.com> <20200324101110.GA2218981@kroah.com> <5E79F102.9080405@samsung.com> <20200324114645.GA2330984@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200324114645.GA2330984@kroah.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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, Mar 24, 2020 at 12:46:45PM +0100, Greg KH wrote: > On Tue, Mar 24, 2020 at 08:37:38PM +0900, Jaewon Kim wrote: > > I don't know other cases in other platform. > > Not desperately needed but I think we need one userspace knob to see overall hidden huge memory. > > Why? Who wants that? What would userspace do with that? And what > exactly do you want to show? > > Is this just a debugging thing? Then use debugfs for that, not proc. Yes, please use debugfs. Android can ban it in production all at once. > Isn't that what the DRM developers are starting to do? > > > Additionally I'd like to see all those hidden memory in OutOfMemory log. > > How is anything hidden, can't you see it in the slab information? There real usecase for something like that is vmware baloon driver. Two VM instances oversteal pages one from another resulting in guest OOM which looks like one giant get_free_page() memory leak from inside VM. I don't know how often this type of issue happens nowadays but countless OOM support tickets were filed and closed over this nonsense.