From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 19 Feb 2007 19:16:20 -0500 From: Chris Mason Subject: Re: dirty balancing deadlock Message-ID: <20070220001620.GK6133@think.oraclecorp.com> References: <20070218125307.4103c04a.akpm@linux-foundation.org> <20070218145929.547c21c7.akpm@linux-foundation.org> <20070218155916.0d3c73a9.akpm@linux-foundation.org> <20070219004537.GB9289@think.oraclecorp.com> <20070219010102.GC9289@think.oraclecorp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Miklos Szeredi Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Mon, Feb 19, 2007 at 02:14:15AM +0100, Miklos Szeredi wrote: > > > > In general, writepage is supposed to do work without blocking on > > > > expensive locks that will get pdflush and dirty reclaim stuck in this > > > > fashion. You'll probably have to take the same approach reiserfs does > > > > in data=journal mode, which is leaving the page dirty if fuse_get_req_wp > > > > is going to block without making progress. > > > > > > Pdflush, and dirty reclaim set wbc->nonblocking to true. > > > balance_dirty_pages and fsync don't. The problem here is that > > > Andrew's patch is wrong to let balance_dirty_pages() try to write back > > > pages from a different queue. > > > > async or sync, writepage is supposed to either make progress or bail. > > loopback aside, if the fuse call is blocking long term, you're going to > > run into problems. > > Hmm, like what? Something a little different from what you're seeing. Basically if the PF_MEMALLOC paths end up waiting on a filesystem transaction, and that transaction is waiting for more ram, the system will eventually grind to a halt. data=journal is the easiest way to hit it, since writepage always logs at least 4k. WB_SYNC_NONE and wbc->nonblocking aren't a great test, in reiser I resorted to testing PF_MEMALLOC. -chris -- 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