From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE From: Benjamin Herrenschmidt 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> <1085521251.24948.127.camel@gaston> Content-Type: text/plain Message-Id: <1085523563.15281.136.camel@gaston> Mime-Version: 1.0 Date: Wed, 26 May 2004 08:19:24 +1000 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Linus Torvalds Cc: "David S. Miller" , wesolows@foobazco.org, willy@debian.org, Andrea Arcangeli , Andrew Morton , Linux Kernel list , mingo@elte.hu, bcrl@kvack.org, linux-mm@kvack.org, Linux Arch list List-ID: On Wed, 2004-05-26 at 08:09, Linus Torvalds wrote: > But if we don't update the hash tables, how will the TLB entry _ever_ say > that the page is writable? So we won't take just _one_ extra fault on the > next write, we'll _keep_ taking them, since the hash tables will continue > to claim that the page is read-only, even if the linux sw page tables say > it is writable. > > So I think the code needs to invalidate the hash after having updated the > pte. No? No, we'll take a hash fault, not a page fault. The hash fault is an asm fast path, which in this case, will update the HPTE RW permission when the PTE has PAGE_RW (and will set PAGE_DIRTY again, but that's fine). Ben. -- 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