From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id A2EF18D0039 for ; Wed, 23 Feb 2011 17:35:04 -0500 (EST) Received: from mail-iw0-f169.google.com (mail-iw0-f169.google.com [209.85.214.169]) (authenticated bits=0) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id p1NMYEbW015064 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=FAIL) for ; Wed, 23 Feb 2011 14:34:14 -0800 Received: by iwl42 with SMTP id 42so5449897iwl.14 for ; Wed, 23 Feb 2011 14:34:14 -0800 (PST) MIME-Version: 1.0 In-Reply-To: References: From: Linus Torvalds Date: Wed, 23 Feb 2011 14:33:54 -0800 Message-ID: Subject: Re: [PATCH] mm: prevent concurrent unmap_mapping_range() on the same inode Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Miklos Szeredi Cc: akpm@linux-foundation.org, hughd@google.com, gurudas.pai@oracle.com, lkml20101129@newton.leun.net, rjw@sisk.pl, florian@mickler.org, trond.myklebust@fys.uio.no, maciej.rutecki@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Wed, Feb 23, 2011 at 4:49 AM, Miklos Szeredi wrote: > > This resolves Bug 25822 listed in the regressions since 2.6.36 (though > it's a bug much older than that, for some reason it only started > triggering for people recently). Gaah. I hate this patch. It is, in fact, a patch that makes me finally think that the mm preemptibility is actually worth it, because then i_mmap_lock turns into a mutex and makes the whole "drop the lock" thing hopefully a thing of the past (see the patch "mm: Remove i_mmap_mutex lockbreak"). Because as far as I can see, the only thing that makes this thing needed in the first place is that horribly ugly "we drop i_mmap_lock in the middle of random operations that really still need it". That said, I don't really see any alternatives - I guess we can't really just say "remove that crazy lock dropping". Even though I really really really would like to. Of course, we could also just decide that we should apply the mm preemptibility series instead. Can people confirm that that fixes the bug too? Linus -- 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