From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 30 Jan 2008 01:05:59 +0100 From: Andrea Arcangeli Subject: Re: [patch 2/6] mmu_notifier: Callbacks to invalidate address ranges Message-ID: <20080130000559.GB7233@v2.random> References: <20080128202840.974253868@sgi.com> <20080128202923.849058104@sgi.com> <20080129162004.GL7233@v2.random> <20080129211759.GV7233@v2.random> <20080129220212.GX7233@v2.random> <20080130000039.GA7233@v2.random> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080130000039.GA7233@v2.random> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Robin Holt , Avi Kivity , Izik Eidus , Nick Piggin , kvm-devel@lists.sourceforge.net, Benjamin Herrenschmidt , Peter Zijlstra , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com, Hugh Dickins List-ID: On Wed, Jan 30, 2008 at 01:00:39AM +0100, Andrea Arcangeli wrote: > get_user_pages, regular linux writes don't fault unless it's > explicitly writeprotect, which is mandatory in a few archs, x86 not). actually get_user_pages doesn't fault either but it calls into set_page_dirty, however get_user_pages (unlike a userland-write) at least requires mmap_sem in read mode and the PT lock as serialization, userland writes don't, they just go ahead and mark the pte in hardware w/o faults. Anyway anonymous memory these days always mapped with dirty bit set regardless, even for read-faults, after Nick finally rightfully cleaned up the zero-page trick. -- 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