From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f54.google.com (mail-pb0-f54.google.com [209.85.160.54]) by kanga.kvack.org (Postfix) with ESMTP id 7918D6B0035 for ; Mon, 3 Feb 2014 18:29:28 -0500 (EST) Received: by mail-pb0-f54.google.com with SMTP id uo5so7641425pbc.41 for ; Mon, 03 Feb 2014 15:29:28 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id yg10si15926591pbc.62.2014.02.03.15.29.27 for ; Mon, 03 Feb 2014 15:29:27 -0800 (PST) Date: Mon, 3 Feb 2014 15:29:25 -0800 From: Andrew Morton Subject: Re: [PATCH 2/8] mm/swap: fix race on swap_info reuse between swapoff and swapon Message-Id: <20140203152925.89360139306d143f5360fa07@linux-foundation.org> In-Reply-To: <20140203152340.b28bb35698ee75615eb23041@linux-foundation.org> References: <000d01cf1b47$f12e11f0$d38a35d0$%yang@samsung.com> <20140203152340.b28bb35698ee75615eb23041@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Weijie Yang , hughd@google.com, 'Minchan Kim' , shli@kernel.org, 'Bob Liu' , weijie.yang.kh@gmail.com, 'Seth Jennings' , 'Heesub Shin' , mquzik@redhat.com, 'Linux-MM' , 'linux-kernel' , stable@vger.kernel.org On Mon, 3 Feb 2014 15:23:40 -0800 Andrew Morton wrote: > On Mon, 27 Jan 2014 18:03:04 +0800 Weijie Yang wrote: > > > swapoff clear swap_info's SWP_USED flag prematurely and free its resources > > after that. A concurrent swapon will reuse this swap_info while its previous > > resources are not cleared completely. > > > > These late freed resources are: > > - p->percpu_cluster > > - swap_cgroup_ctrl[type] > > - block_device setting > > - inode->i_flags &= ~S_SWAPFILE > > > > This patch clear SWP_USED flag after all its resources freed, so that swapon > > can reuse this swap_info by alloc_swap_info() safely. > > > > This patch is just for a rare scenario, aim to correct of code. > > I believe that > http://ozlabs.org/~akpm/mmots/broken-out/mm-swap-fix-race-on-swap_info-reuse-between-swapoff-and-swapon.patch > makes this patch redundant? > oop, hang on. This patch *is* a stealth-updated version of http://ozlabs.org/~akpm/mmots/broken-out/mm-swap-fix-race-on-swap_info-reuse-between-swapoff-and-swapon.patch. Undocumented removals of si->swap_map have been added. What's going on there? I think I'll stick with the original patch for now. If you see additional optimisations or changes, let's address that separately? -- 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