From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 30 May 2003 18:00:27 -0700 From: Andrew Morton Subject: Re: [RFC][PATCH] Convert do_no_page() to a hook to avoid DFS race Message-Id: <20030530180027.75680efd.akpm@digeo.com> In-Reply-To: <20030530164150.A26766@us.ibm.com> References: <20030530164150.A26766@us.ibm.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: paulmck@us.ibm.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, hch@infradead.org List-ID: "Paul E. McKenney" wrote: > > Rediffed to 2.5.70-mm2. > > This patch allows a distributed filesystem to avoid the > pagefault/cross-node-invalidate race described in: > > http://marc.theaimsgroup.com/?l=linux-kernel&m=105286345316249&w=2 > > This patch converts the bulk of do_no_page() into a hook that may > be called from the ->nopage vm_operations_struct callout. Seems reasonable. > There > is still an inlined do_no_page() wrapper due to the fact that > do_anonymous_page() requires that the mm->page_table_lock be > held on entry, while the ->nopage callouts require that this > lock be dropped. I sugest you change the ->nopage definition so that page_table_lock is held on entry to ->nopage, and ->nopage must drop it at some point. This gives the nopage implementations some more flexibility and may perhaps eliminate that special case? > This patch is untested. I don't think there's a lot of point in making changes until the code which requires those changes is accepted into the tree. Otherwise it may be pointless churn, and there's nothing in-tree to exercise the new features. > An alternative to this patch includes the nopagedone() patch posted > moments ago. hch has also suggested that do_anonymous_page() be > converted to a ->nopage callout, but this would require that all > of the other ->nopage callouts drop mm->page_table_lock as their > first action. If people believe that this is the right thing to > do, I will happily produce such a patch. That sounds better to me. -- 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