From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f199.google.com (mail-qt0-f199.google.com [209.85.216.199]) by kanga.kvack.org (Postfix) with ESMTP id 50FD46B0038 for ; Fri, 17 Nov 2017 10:56:05 -0500 (EST) Received: by mail-qt0-f199.google.com with SMTP id z37so3844641qtz.16 for ; Fri, 17 Nov 2017 07:56:05 -0800 (PST) Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com. [67.231.145.42]) by mx.google.com with ESMTPS id a24si3922123qkj.286.2017.11.17.07.56.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 17 Nov 2017 07:56:04 -0800 (PST) Date: Fri, 17 Nov 2017 15:55:16 +0000 From: Roman Gushchin Subject: Re: [PATCH] mm/shmem: set default tmpfs size according to memcg limit Message-ID: <20171117155509.GA920@castle> References: <1510888199-5886-1-git-send-email-laoar.shao@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Shakeel Butt Cc: Yafang Shao , Andrew Morton , Johannes Weiner , Vladimir Davydov , Michal Hocko , Tejun Heo , khlebnikov@yandex-team.ru, mka@chromium.org, Hugh Dickins , Cgroups , Linux MM , LKML On Thu, Nov 16, 2017 at 08:43:17PM -0800, Shakeel Butt wrote: > On Thu, Nov 16, 2017 at 7:09 PM, Yafang Shao wrote: > > Currently the default tmpfs size is totalram_pages / 2 if mount tmpfs > > without "-o size=XXX". > > When we mount tmpfs in a container(i.e. docker), it is also > > totalram_pages / 2 regardless of the memory limit on this container. > > That may easily cause OOM if tmpfs occupied too much memory when swap is > > off. > > So when we mount tmpfs in a memcg, the default size should be limited by > > the memcg memory.limit. > > > > The pages of the tmpfs files are charged to the memcg of allocators > which can be in memcg different from the memcg in which the mount > operation happened. So, tying the size of a tmpfs mount where it was > mounted does not make much sense. Also, memory limit is adjustable, and using a particular limit value at a moment of tmpfs mounting doesn't provide any warranties further. Is there a reason why the userspace app which is mounting tmpfs can't set the size based on memory.limit? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org