From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 894F06B004D for ; Tue, 9 Jun 2009 07:41:35 -0400 (EDT) Date: Tue, 9 Jun 2009 14:17:22 +0200 From: Nick Piggin Subject: Re: [PATCH] [13/16] HWPOISON: The high level memory error handler in the VM v3 Message-ID: <20090609121722.GC9158@wotan.suse.de> References: <20090528134520.GH1065@one.firstfloor.org> <20090528145021.GA5503@localhost> <20090607160225.GA24315@localhost> <20090608123133.GA7944@localhost> <20090609064855.GB5490@localhost> <20090609104825.GJ14820@wotan.suse.de> <20090609121510.GB5589@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090609121510.GB5589@localhost> Sender: owner-linux-mm@kvack.org To: Wu Fengguang Cc: Nai Xia , Andi Kleen , "hugh@veritas.com" , "riel@redhat.com" , "akpm@linux-foundation.org" , "chris.mason@oracle.com" , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" List-ID: On Tue, Jun 09, 2009 at 08:15:10PM +0800, Wu Fengguang wrote: > On Tue, Jun 09, 2009 at 06:48:25PM +0800, Nick Piggin wrote: > > On Tue, Jun 09, 2009 at 02:48:55PM +0800, Wu Fengguang wrote: > > > On Mon, Jun 08, 2009 at 10:46:53PM +0800, Nai Xia wrote: > > > > I meant PG_writeback stops writers to index---->struct page mapping. > > > > > > It's protected by the radix tree RCU locks. Period. > > > > > > If you are referring to the reverse mapping: page->mapping is procted > > > by PG_lock. No one should make assumption that it won't change under > > > page writeback. > > > > Well... I think probably PG_writeback should be enough. Phrased another > > way: I think it is a very bad idea to truncate PG_writeback pages out of > > pagecache. Does anything actually do that? > > There shall be no one. OK I will follow that convention.. > > But as I stated it is only safe do rely on the fact "no one truncates > PG_writeback pages" in end_writeback_io handlers. And I suspect if > there does exist such a handler, it could be trivially converted to > take the page lock. Well, the writeback submitter first sets writeback, then unlocks the page. I don't think he wants a truncate coming in at that point. -- 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