From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f72.google.com (mail-wm0-f72.google.com [74.125.82.72]) by kanga.kvack.org (Postfix) with ESMTP id 7CA352803A5 for ; Wed, 30 Aug 2017 01:27:01 -0400 (EDT) Received: by mail-wm0-f72.google.com with SMTP id v2so904487wmd.11 for ; Tue, 29 Aug 2017 22:27:01 -0700 (PDT) Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com. [148.163.158.5]) by mx.google.com with ESMTPS id p17si3538668wra.451.2017.08.29.22.26.59 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 29 Aug 2017 22:27:00 -0700 (PDT) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v7U5O1ZK112226 for ; Wed, 30 Aug 2017 01:26:59 -0400 Received: from e23smtp06.au.ibm.com (e23smtp06.au.ibm.com [202.81.31.148]) by mx0b-001b2d01.pphosted.com with ESMTP id 2cndnvvdut-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 30 Aug 2017 01:26:58 -0400 Received: from localhost by e23smtp06.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 30 Aug 2017 15:26:56 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay07.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v7U5Pdm240108270 for ; Wed, 30 Aug 2017 15:25:39 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v7U5PTP2016996 for ; Wed, 30 Aug 2017 15:25:29 +1000 Subject: Re: [PATCH v2 14/20] mm: Provide speculative fault infrastructure References: <1503007519-26777-1-git-send-email-ldufour@linux.vnet.ibm.com> <1503007519-26777-15-git-send-email-ldufour@linux.vnet.ibm.com> <20170827001823.n5wgkfq36z6snvf2@node.shutemov.name> From: Anshuman Khandual Date: Wed, 30 Aug 2017 10:55:27 +0530 MIME-Version: 1.0 In-Reply-To: <20170827001823.n5wgkfq36z6snvf2@node.shutemov.name> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Message-Id: Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" , Laurent Dufour Cc: paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox , benh@kernel.crashing.org, mpe@ellerman.id.au, paulus@samba.org, Thomas Gleixner , Ingo Molnar , hpa@zytor.com, Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, bsingharora@gmail.com, Tim Chen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org On 08/27/2017 05:48 AM, Kirill A. Shutemov wrote: >> + /* Transparent huge pages are not supported. */ >> + if (unlikely(pmd_trans_huge(*pmd))) >> + goto out_walk; > That's looks like a blocker to me. > > Is there any problem with making it supported (besides plain coding)? IIUC we would have to reattempt once for each PMD level fault because of the lack of a page table entry there. Besides do we want to support huge pages in general as part of speculative page fault path ? The number of faults will be very less (256 times lower on POWER and 512 times lower on X86). So is it worth it ? BTW calling hugetlb_fault() after figuring out the VMA, works correctly inside handle_speculative _fault() last time I checked. -- 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