From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pb0-f50.google.com (mail-pb0-f50.google.com [209.85.160.50]) by kanga.kvack.org (Postfix) with ESMTP id 530346B0035 for ; Mon, 3 Feb 2014 18:36:31 -0500 (EST) Received: by mail-pb0-f50.google.com with SMTP id rq2so7715122pbb.9 for ; Mon, 03 Feb 2014 15:36:31 -0800 (PST) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org. [140.211.169.12]) by mx.google.com with ESMTP id ay1si15078326pbd.186.2014.02.03.15.36.30 for ; Mon, 03 Feb 2014 15:36:30 -0800 (PST) Date: Mon, 3 Feb 2014 15:36:28 -0800 From: Andrew Morton 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> 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 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 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, 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