From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 12 Jun 2008 15:29:05 -0400 From: Rik van Riel Subject: Re: 2.6.26-rc5-mm2 Message-ID: <20080612152905.6cb294ae@cuia.bos.redhat.com> In-Reply-To: <200806120958.38545.nickpiggin@yahoo.com.au> References: <20080609223145.5c9a2878.akpm@linux-foundation.org> <200806101848.22237.nickpiggin@yahoo.com.au> <20080611140902.544e59ec@bree.surriel.com> <200806120958.38545.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Andrew Morton , linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org, linux-mm@kvack.org List-ID: On Thu, 12 Jun 2008 09:58:38 +1000 Nick Piggin wrote: > > Does loopback over tmpfs use a different allocation path? > > I'm sorry, hmm I didn't look closely enough and forgot that > write_begin/write_end requires the callee to allocate the page > as well, and that Hugh had nicely unified most of that. > > So maybe it's not that. It's pretty easy to hit I found with > ext2 mounted over loopback on a tmpfs file. Turns out the loopback driver uses splice, which moves the pages from one place to another. This is why you were seeing the problem with loopback, but not with just a really big file on tmpfs. I'm trying to make sense of all the splice code now and will send fix as soon as I know how to fix this problem in a nice way. -- All Rights Reversed -- 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