From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 25 May 2004 13:57:48 -0700 From: "David S. Miller" Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE Message-Id: <20040525135748.296ba888.davem@redhat.com> In-Reply-To: References: <1085369393.15315.28.camel@gaston> <1085371988.15281.38.camel@gaston> <1085373839.14969.42.camel@gaston> <20040525034326.GT29378@dualathlon.random> <20040525114437.GC29154@parcelfarce.linux.theplanet.co.uk> <20040525153501.GA19465@foobazco.org> <20040525102547.35207879.davem@redhat.com> <20040525105442.2ebdc355.davem@redhat.com> <20040525133543.753fc5a5.davem@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: wesolows@foobazco.org, willy@debian.org, andrea@suse.de, benh@kernel.crashing.org, akpm@osdl.org, linux-kernel@vger.kernel.org, mingo@elte.hu, bcrl@kvack.org, linux-mm@kvack.org, linux-arch@vger.kernel.org List-ID: On Tue, 25 May 2004 13:49:57 -0700 (PDT) Linus Torvalds wrote: > So it sounds like the SWAP loop basically ends up being just something > like ... > Right? Note that the reason we can do the "dirty and accessed bit both > set" case with a simple write is exactly because that's already the > "maximal" bits anybody can write to the thing, so we don't need to loop, > we can just write it directly. I believe so. So it's still possible for the mmu to write something with less bits, ie. say we're adding dirty, we write dirty+accessed but the TLB has the pre-dirty PTE and writes that with just the accessed bit set. And this is exactly what you code is trying to handle. Perfect. -- 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: aart@kvack.org