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Mon, 13 Jun 2022 12:11:18 +0000 (UTC) Date: Mon, 13 Jun 2022 14:11:17 +0200 From: Michal Hocko To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: Christian =?iso-8859-1?Q?K=F6nig?= , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, nouveau@lists.freedesktop.org, linux-tegra@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, alexander.deucher@amd.com, daniel@ffwll.ch, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, hughd@google.com, andrey.grodzovsky@amd.com Subject: Re: [PATCH 03/13] mm: shmem: provide oom badness for shmem files Message-ID: References: <3f7d3d96-0858-fb6d-07a3-4c18964f888e@gmail.com> <2e7e050e-04eb-0c0a-0675-d7f1c3ae7aed@amd.com> <288528c3-411e-fb25-2f08-92d4bb9f1f13@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; 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dkim=pass header.d=suse.com header.s=susede1 header.b=fWc9Ypl2; dmarc=pass (policy=quarantine) header.from=suse.com; spf=pass (imf25.hostedemail.com: domain of mhocko@suse.com designates 195.135.220.29 as permitted sender) smtp.mailfrom=mhocko@suse.com X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1655122282-273429 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 Mon 13-06-22 13:50:28, Christian König wrote: > Am 13.06.22 um 09:45 schrieb Michal Hocko: > > On Sat 11-06-22 10:06:18, Christian König wrote: > > > Am 10.06.22 um 16:16 schrieb Michal Hocko: [...] > > > Alternative I could try to track the "owner" of a buffer (e.g. a shmem > > > file), but then it can happen that one processes creates the object and > > > another one is writing to it and actually allocating the memory. > > If you can enforce that the owner is really responsible for the > > allocation then all should be fine. That would require MAP_POPULATE like > > semantic and I suspect this is not really feasible with the existing > > userspace. It would be certainly hard to enforce for bad players. > > I've tried this today and the result was: "BUG: Bad rss-counter state > mm:000000008751d9ff type:MM_FILEPAGES val:-571286". > > The problem is once more that files are not informed when the process > clones. So what happened is that somebody called fork() with an mm_struct > I've accounted my pages to. The result is just that we messed up the > rss_stats and  the the "BUG..." above. > > The key difference between normal allocated pages and the resources here is > just that we are not bound to an mm_struct in any way. It is not really clear to me what exactly you have tried. -- Michal Hocko SUSE Labs