From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sat, 14 Oct 2000 14:33:09 +0100 From: Stephen Tweedie Subject: Re: [RFC] atomic pte updates and pae changes, take 2 Message-ID: <20001014143309.D5813@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ; from bcrl@redhat.com on Fri, Oct 13, 2000 at 08:17:42PM -0400 Sender: owner-linux-mm@kvack.org Return-Path: To: Ben LaHaise Cc: torvalds@transmeta.com, Ingo Molnar , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Stephen Tweedie List-ID: Hi, On Fri, Oct 13, 2000 at 08:17:42PM -0400, Ben LaHaise wrote: > > Below is take two of the patch making pte_clear use atomic xchg in an > effort to avoid the loss of dirty bits. PAE no longer uses cmpxchg8 for > updates; set_pte is two ordered long writes with a barrier. Looks good. The only trouble I can see left is that pte_clear() is still using set_pte(), which doesn't work right for PAE36. set_pte() is setting the high word first, which is fine for installing a new pte, but if you do that to clear a pte then you have left the old page-present bit intact while you've removed have of the pte. pte_clear() needs to clear the words in the other order (just as pte_get_and_clear correctly does). Cheers, Stephen -- 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.eu.org/Linux-MM/