Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754614AbaBCXgm (ORCPT ); Mon, 3 Feb 2014 18:36:42 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:47310 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753701AbaBCXga (ORCPT ); Mon, 3 Feb 2014 18:36:30 -0500 Date: Mon, 3 Feb 2014 15:36:28 -0800 From: Andrew Morton To: Weijie Yang Cc: 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 Subject: Re: [PATCH 3/8] mm/swap: prevent concurrent swapon on the same S_ISBLK blockdev Message-Id: <20140203153628.5e186b0e4e81400773faa7ac@linux-foundation.org> In-Reply-To: <000c01cf1b47$ce280170$6a780450$%yang@samsung.com> References: <000c01cf1b47$ce280170$6a780450$%yang@samsung.com> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 27 Jan 2014 18:03:04 +0800 Weijie Yang wrote: > When swapon the same S_ISBLK blockdev concurrent, the allocated two > swap_info could hold the same block_device, because claim_swapfile() > allow the same holder(here, it is sys_swapon function). > > To prevent this situation, This patch adds swap_lock protect to ensure > we can find this situation and return -EBUSY for one swapon call. > > As for S_ISREG swapfile, claim_swapfile() already prevent this scenario > by holding inode->i_mutex. > > This patch is just for a rare scenario, aim to correct of code. > hm, OK. Would it be saner to pass a unique `holder' to claim_swapfile()? Say, `p'? Truly, I am fed up with silly swapon/swapoff races. How often does anyone call these things? Let's slap a huge lock around the whole thing and be done with it? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/