From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with ESMTP id 811BB6B0206 for ; Sun, 4 Apr 2010 15:55:52 -0400 (EDT) Date: Sun, 4 Apr 2010 21:55:33 +0200 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: why are some low-level MM routines being exported? Message-ID: <20100404195533.GA8836@logfs.org> References: <1270396784.1814.92.camel@barrios-desktop> <20100404160328.GA30540@ioremap.net> <1270398112.1814.114.camel@barrios-desktop> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1270398112.1814.114.camel@barrios-desktop> Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Evgeniy Polyakov , "Robert P. J. Day" , linux-mm@kvack.org List-ID: On Mon, 5 April 2010 01:21:52 +0900, Minchan Kim wrote: > > > Until now, other file system don't need it. > Why do you need? To avoid deadlocks. You tell logfs to write out some locked page, logfs determines that it needs to run garbage collection first. Garbage collection can read any page. If it called find_or_create_page() for the locked page, you have a deadlock. I don't know how (or if) jffs2 and ubifs can avoid this particular scenario. The other filesystems lack garbage collection, so the problem does not exist. JA?rn -- Joern's library part 5: http://www.faqs.org/faqs/compression-faq/part2/section-9.html -- 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