From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx161.postini.com [74.125.245.161]) by kanga.kvack.org (Postfix) with SMTP id 072D76B007E for ; Thu, 1 Mar 2012 17:40:31 -0500 (EST) Date: Thu, 1 Mar 2012 17:40:14 -0500 From: Dave Jones Subject: Re: [PATCH -V2] hugetlbfs: Drop taking inode i_mutex lock from hugetlbfs_read Message-ID: <20120301224014.GA21990@redhat.com> References: <1330593530-2022-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <20120301141007.274ad458.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120301141007.274ad458.akpm@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Aneesh Kumar K.V" , linux-mm@kvack.org, mgorman@suse.de, kamezawa.hiroyu@jp.fujitsu.com, dhillf@gmail.com, viro@zeniv.linux.org.uk, hughd@google.com, linux-kernel@vger.kernel.org On Thu, Mar 01, 2012 at 02:10:07PM -0800, Andrew Morton wrote: > > AFAIU i_mutex lock got added to hugetlbfs_read as per > > http://lkml.indiana.edu/hypermail/linux/kernel/0707.2/3066.html > > to take care of the race between truncate and read. This patch fix > > this by looking at page->mapping under page_lock (find_lock_page()) > > to ensure; the inode didn't get truncated in the range during a > > parallel read. > > > > Ideally we can extend the patch to make sure we don't increase i_size > > in mmap. But that will break userspace, because application will now > > have to use truncate(2) to increase i_size in hugetlbfs. > > Looks OK to me. > > Given that the bug has been there for four years, I'm assuming that > we'll be OK merging this fix into 3.4. Or we could merge it into 3.4 > and tag it for backporting into earlier kernels - it depends on whether > people are hurting from it, which I don't know? My testing hits this every day. It's not a real problem, but it's annoying to see the lockdep spew constantly. We've had a couple Fedora users report it too in regular day-to-day use as opposed to the hostile workloads I use to provoke it. FWIW, I'll probably throw it in the Fedora kernels, so if it ends up in stable, it'll be one less patch to carry. Dave -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org