From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx172.postini.com [74.125.245.172]) by kanga.kvack.org (Postfix) with SMTP id 8EA3E6B0044 for ; Thu, 23 Aug 2012 18:10:09 -0400 (EDT) Received: from /spool/local by e31.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Aug 2012 16:10:08 -0600 Received: from d03relay01.boulder.ibm.com (d03relay01.boulder.ibm.com [9.17.195.226]) by d03dlp01.boulder.ibm.com (Postfix) with ESMTP id 408F4C40004 for ; Thu, 23 Aug 2012 16:10:06 -0600 (MDT) Received: from d03av05.boulder.ibm.com (d03av05.boulder.ibm.com [9.17.195.85]) by d03relay01.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q7NMA3iM162608 for ; Thu, 23 Aug 2012 16:10:04 -0600 Received: from d03av05.boulder.ibm.com (loopback [127.0.0.1]) by d03av05.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q7NMA2sF004709 for ; Thu, 23 Aug 2012 16:10:03 -0600 Message-ID: <5036AA38.6010400@linux.vnet.ibm.com> Date: Thu, 23 Aug 2012 17:10:00 -0500 From: Seth Jennings MIME-Version: 1.0 Subject: Re: [PATCH 0/2] revert changes to zcache_do_preload() References: <1345735991-6995-1-git-send-email-sjenning@linux.vnet.ibm.com> <20120823205648.GA2066@barrios> In-Reply-To: <20120823205648.GA2066@barrios> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Greg Kroah-Hartman , Andrew Morton , Nitin Gupta , Konrad Rzeszutek Wilk , Dan Magenheimer , linux-mm@kvack.org, linux-kernel@vger.kernel.org, devel@driverdev.osuosl.org, xiaoguangrong@linux.vnet.ibm.com On 08/23/2012 03:56 PM, Minchan Kim wrote: > Hi Seth, > > On Thu, Aug 23, 2012 at 10:33:09AM -0500, Seth Jennings wrote: >> This patchset fixes a regression in 3.6 by reverting two dependent >> commits that made changes to zcache_do_preload(). >> >> The commits undermine an assumption made by tmem_put() in >> the cleancache path that preemption is disabled. This change >> introduces a race condition that can result in the wrong page >> being returned by tmem_get(), causing assorted errors (segfaults, >> apparent file corruption, etc) in userspace. >> >> The corruption was discussed in this thread: >> https://lkml.org/lkml/2012/8/17/494 > > I think changelog isn't enough to explain what's the race. > Could you write it down in detail? I didn't come upon this solution via code inspection, but rather through discovering that the issue didn't exist in v3.5 and just looking at the changes since then. > And you should Cc'ed Xiao who is author of reverted patch. Thanks for adding Xiao. I meant to do this. For some reason I thought that you submitted that patchset :-/ My bad. Seth -- 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