From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755825AbYKMACt (ORCPT ); Wed, 12 Nov 2008 19:02:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753624AbYKMACk (ORCPT ); Wed, 12 Nov 2008 19:02:40 -0500 Received: from mga01.intel.com ([192.55.52.88]:61936 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753597AbYKMACk convert rfc822-to-8bit (ORCPT ); Wed, 12 Nov 2008 19:02:40 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.33,592,1220252400"; d="scan'208";a="402959137" From: "Pallipadi, Venkatesh" To: Nick Piggin CC: Ingo Molnar , Thomas Gleixner , H Peter Anvin , Hugh Dickins , Roland Dreier , Jesse Barnes , Jeremy Fitzhardinge , Arjan van de Ven , "linux-kernel@vger.kernel.org" , "Siddha, Suresh B" Date: Wed, 12 Nov 2008 16:02:47 -0800 Subject: RE: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn Thread-Topic: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn Thread-Index: AclFHafQxzuoc2l2QPWPiQyZvDNKcgABFZzg Message-ID: <7E82351C108FA840AB1866AC776AEC46426F30E5@orsmsx505.amr.corp.intel.com> References: <20081112212647.259698000@intel.com> <20081112212900.151113000@intel.com> <20081112232312.GB29363@wotan.suse.de> In-Reply-To: <20081112232312.GB29363@wotan.suse.de> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >-----Original Message----- >From: Nick Piggin [mailto:npiggin@suse.de] >Sent: Wednesday, November 12, 2008 3:23 PM >To: Pallipadi, Venkatesh >Cc: Ingo Molnar; Thomas Gleixner; H.Peter Anvin; Hugh Dickins; >Roland Dreier; Jesse Barnes; Jeremy Fitzhardinge; Arjan van de >Ven; linux-kernel@vger.kernel.org; Siddha, Suresh B >Subject: Re: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn > >You have to be careful of this, because it can be called with mmap_sem >held for read only. Hmm, I guess vm_insert_page is doing the >same thing. >Probably mostly works because all other modifiers of vm_flags >are holding >mmap_sem. Yes. I did the patch looking at vm_insert_page doing similar thing. > >However, in some cases, code can do vm_insert_pfn and vm_insert_page >(actually hmm, no vm_insert_mixed actually should cover most of those >cases). > >Still, I'd be much happier if we could make these into BUG_ON, and then >teach callers to set it in their .mmap routines. Actually, vm_insert_pfn() already has a BUG_ON() at the start for cases where neither (or both) MIXEDMAP and PFNMAP is not set. So, that should cover the case we are worried about it here and we can eliminate this patch altogether. Only part I am not sure about is why we are looking for MIXEDMAP here. Shouldn't they be using vm_insert_mixed instead? Thanks, Venki