From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16566.25617.363386.115466@napali.hpl.hp.com> Date: Thu, 27 May 2004 14:56:33 -0700 Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE In-Reply-To: <20040525045322.GX29378@dualathlon.random> References: <1085369393.15315.28.camel@gaston> <1085371988.15281.38.camel@gaston> <1085373839.14969.42.camel@gaston> <20040525034326.GT29378@dualathlon.random> <20040525042054.GU29378@dualathlon.random> <16562.52948.981913.814783@napali.hpl.hp.com> <20040525045322.GX29378@dualathlon.random> Reply-To: davidm@hpl.hp.com Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: davidm@hpl.hp.com, Linus Torvalds , Benjamin Herrenschmidt , Andrew Morton , Linux Kernel list , Ingo Molnar , Ben LaHaise , linux-mm@kvack.org, Architectures Group List-ID: >>>>> On Tue, 25 May 2004 06:53:22 +0200, Andrea Arcangeli said: >> If the "accessed" or "dirty" bits are zero, accessing/writing the >> page will cause a fault which will be handled in a low-level >> fault handler. The Linux version of these handlers simply turn >> on the respective bit. See daccess_bit(), iaccess_bit(), and dirty_bit() >> in arch/ia64/kernel/ivt.S. Andrea> so you mean, this is being set in the arch section before Andrea> ever reaching handle_mm_fault? Correct. The low-level fault handlers set the ACCESSED/DIRTY bits with an atomic compare-and-exchange (on SMP). They don't (normally) bubble up all the way to the Linux page-fault handler. --david -- 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