From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932669Ab2GEORJ (ORCPT ); Thu, 5 Jul 2012 10:17:09 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:62720 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932299Ab2GEORI (ORCPT ); Thu, 5 Jul 2012 10:17:08 -0400 Date: Thu, 5 Jul 2012 15:17:00 +0100 From: Will Deacon To: Hillf Danton Cc: "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "mhocko@suse.cz" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] mm: hugetlb: flush dcache before returning zeroed huge page to userspace Message-ID: <20120705141700.GI3399@mudshark.cambridge.arm.com> References: <1341412376-6272-1-git-send-email-will.deacon@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 05, 2012 at 01:37:46PM +0100, Hillf Danton wrote: > On Wed, Jul 4, 2012 at 10:32 PM, Will Deacon wrote: > > When allocating and returning clear huge pages to userspace as a > > response to a fault, we may zero and return a mapping to a previously > > dirtied physical region (for example, it may have been written by > > a private mapping which was freed as a result of an ftruncate on the > > backing file). On architectures with Harvard caches, this can lead to > > I/D inconsistency since the zeroed view may not be visible to the > > instruction stream. > > > > This patch solves the problem by flushing the region after allocating > > and clearing a new huge page. Note that PowerPC avoids this issue by > > performing the flushing in their clear_user_page implementation to keep > > the loader happy, however this is closely tied to the semantics of the > > PG_arch_1 page flag which is architecture-specific. > > > > Acked-by: Catalin Marinas > > Signed-off-by: Will Deacon > > --- > > Thanks:) > > Acked-by: Hillf Danton Thanks Hillf. Which tree does this stuff usually go through? Will From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx138.postini.com [74.125.245.138]) by kanga.kvack.org (Postfix) with SMTP id 4985C6B0071 for ; Thu, 5 Jul 2012 10:17:03 -0400 (EDT) Date: Thu, 5 Jul 2012 15:17:00 +0100 From: Will Deacon Subject: Re: [PATCH] mm: hugetlb: flush dcache before returning zeroed huge page to userspace Message-ID: <20120705141700.GI3399@mudshark.cambridge.arm.com> References: <1341412376-6272-1-git-send-email-will.deacon@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Hillf Danton Cc: "linux-mm@kvack.org" , "akpm@linux-foundation.org" , "mhocko@suse.cz" , "linux-kernel@vger.kernel.org" On Thu, Jul 05, 2012 at 01:37:46PM +0100, Hillf Danton wrote: > On Wed, Jul 4, 2012 at 10:32 PM, Will Deacon wrote: > > When allocating and returning clear huge pages to userspace as a > > response to a fault, we may zero and return a mapping to a previously > > dirtied physical region (for example, it may have been written by > > a private mapping which was freed as a result of an ftruncate on the > > backing file). On architectures with Harvard caches, this can lead to > > I/D inconsistency since the zeroed view may not be visible to the > > instruction stream. > > > > This patch solves the problem by flushing the region after allocating > > and clearing a new huge page. Note that PowerPC avoids this issue by > > performing the flushing in their clear_user_page implementation to keep > > the loader happy, however this is closely tied to the semantics of the > > PG_arch_1 page flag which is architecture-specific. > > > > Acked-by: Catalin Marinas > > Signed-off-by: Will Deacon > > --- > > Thanks:) > > Acked-by: Hillf Danton Thanks Hillf. Which tree does this stuff usually go through? Will -- 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