From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 11 Oct 2006 23:43:30 -0700 From: Andrew Morton Subject: Re: [RFC][PATCH] EXT3: problem with page fault inside a transaction Message-Id: <20061011234330.efae4265.akpm@osdl.org> In-Reply-To: <87mz82vzy1.fsf@sw.ru> References: <87mz82vzy1.fsf@sw.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Dmitriy Monakhov Cc: Linux Kernel , Linux Memory Management , devel@openvz.org, ext2-devel@lists.sourceforge.net, Andrey Savochkin List-ID: 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. > Our customers complain about this issue. Really? How often? What on earth are they doing to trigger this? writev() without the 2.6.18 writev() bugfix? -- 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