Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751099AbWEaQ05 (ORCPT ); Wed, 31 May 2006 12:26:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751687AbWEaQ05 (ORCPT ); Wed, 31 May 2006 12:26:57 -0400 Received: from smtp102.mail.mud.yahoo.com ([209.191.85.212]:10370 "HELO smtp102.mail.mud.yahoo.com") by vger.kernel.org with SMTP id S1750957AbWEaQ04 (ORCPT ); Wed, 31 May 2006 12:26:56 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=q37AapZlLJatddbbdDcSpMeY9B1mJX3pC7FUS9NbnLUfjGE+aaQeJvoaQIx66anaMCn6Ql7ue9CibTINYadqI4Nv0Z48DGWXXq/oUZH7JWKXcpeJ45h0W7r/f8dc5eJmSVCHWyj49DB2KdU//MTVusjOjXVjccewON7DJW4uKvQ= ; Message-ID: <447DC3C6.3030709@yahoo.com.au> Date: Thu, 01 Jun 2006 02:26:46 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Linus Torvalds CC: linux-kernel@vger.kernel.org, hugh@veritas.com, axboe@suse.de Subject: Re: [rfc][patch] remove racy sync_page? References: <447AC011.8050708@yahoo.com.au> <20060529121556.349863b8.akpm@osdl.org> <447B8CE6.5000208@yahoo.com.au> <20060529183201.0e8173bc.akpm@osdl.org> <447BB3FD.1070707@yahoo.com.au> <447BD31E.7000503@yahoo.com.au> <447BD63D.2080900@yahoo.com.au> <447CE43A.6030700@yahoo.com.au> <447D9A41.8040601@yahoo.com.au> <447DAEDE.5070305@yahoo.com.au> <447DB765.6030702@yahoo.com.au> In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1292 Lines: 31 Linus Torvalds wrote: > And I suspect your objection to unplugging is not really about unplugging > itself. It's literally about the fact that we use the same page lock for > IO and for the ->mapping thing, isn't it? Nearly, but not quite that far: it's that we sync_page in lock_page. I don't think using the single lock for both is too bad (in many ways they are related eg. you don't want the page to be truncated while IO is in progress). > > IOW, you don't actually dislike plugging itself, you dislike it due to the > effects of a totally unrelated locking issue, namely that we use the same > lock for two totally independent things. If the ->mapping thing were to > use a PG_map_lock that didn't affect plugging one way or the other, you > wouldn't have any issues with unplugging, would you? > > And I think _that_ is what really gets us to the problem. No I don't dislike plugging at all ;) Just this tangle as you say. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/