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> <1085522860.15315.133.camel@gaston> <1085530867.14969.143.camel@gaston> <1085541906.14969.412.camel@gaston> <1085544720.5580.9.camel@gaston> <1085545114.5578.11.camel@gaston> Content-Type: text/plain Message-Id: <1085546972.5580.23.camel@gaston> Mime-Version: 1.0 Date: Wed, 26 May 2004 14:49:32 +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 14:50, Linus Torvalds wrote: > On Wed, 26 May 2004, Benjamin Herrenschmidt wrote: > > > > Hrm... Still dies, some kind of loop it seems, I'll have a look > > Are you sure the it's not just taking infinite page fault because we keep > reloading the old value from the hash tables? That "hash fault" thing > still doesn't convince me. Why should the hash-refill fastpath ever look > at the software page tables? Where do you think the hash PTE is filled from ? :) We even use one of the linux PTE bits as a lock bit during the hash refill (the PAGE_BUSY bit) to avoid a race where we can end up filling more than one hash entry from the same linux PTE. 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