From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <452DE82F.3080803@yahoo.com.au> Date: Thu, 12 Oct 2006 17:01:03 +1000 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction References: <87mz82vzy1.fsf@sw.ru> <20061011234330.efae4265.akpm@osdl.org> In-Reply-To: <20061011234330.efae4265.akpm@osdl.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Dmitriy Monakhov , Linux Kernel , Linux Memory Management , devel@openvz.org, ext2-devel@lists.sourceforge.net, Andrey Savochkin List-ID: Andrew Morton wrote: > On Thu, 12 Oct 2006 09:57:26 +0400 > Dmitriy Monakhov wrote: > > >>While reading Andrew's generic_file_buffered_write patches i've remembered >>one more EXT3 issue.journal_start() in prepare_write() causes different ranking >>violations if copy_from_user() triggers a page fault. It could cause >>GFP_FS allocation, re-entering into ext3 code possibly with a different >>superblock and journal, ranking violation of journalling serialization >>and mmap_sem and page lock and all other kinds of funny consequences. > > > With the stuff Nick and I are looking at, we won't take pagefaults inside > prepare_write()/commit_write() any more. Yep. Because the page is locked, it is too much to deal with even without a filesystem in the picture. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- 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