From patchwork Sat Apr 16 00:23:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "kirill.shutemov@linux.intel.com" X-Patchwork-Id: 8860321 Return-Path: X-Original-To: patchwork-linux-fsdevel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 49B1EBF29F for ; Sat, 16 Apr 2016 00:31:33 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 7D93F20259 for ; Sat, 16 Apr 2016 00:31:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9977B20107 for ; Sat, 16 Apr 2016 00:31:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752580AbcDPAYS (ORCPT ); Fri, 15 Apr 2016 20:24:18 -0400 Received: from mga14.intel.com ([192.55.52.115]:43113 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752554AbcDPAYR (ORCPT ); Fri, 15 Apr 2016 20:24:17 -0400 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga103.fm.intel.com with ESMTP; 15 Apr 2016 17:24:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,489,1455004800"; d="scan'208";a="933504976" Received: from black.fi.intel.com ([10.237.72.93]) by orsmga001.jf.intel.com with ESMTP; 15 Apr 2016 17:24:12 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 6781652A; Sat, 16 Apr 2016 03:24:06 +0300 (EEST) From: "Kirill A. Shutemov" To: Hugh Dickins , Andrea Arcangeli , Andrew Morton Cc: Dave Hansen , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Jerome Marchand , Yang Shi , Sasha Levin , Andres Lagar-Cavilla , Ning Qu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv7 10/29] thp: handle file COW faults Date: Sat, 16 Apr 2016 03:23:41 +0300 Message-Id: <1460766240-84565-11-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1460766240-84565-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1460766240-84565-1-git-send-email-kirill.shutemov@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-7.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP File COW for THP is handled on pte level: just split the pmd. It's not clear how benefitial would be allocation of huge pages on COW faults. And it would require some code to make them work. I think at some point we can consider teaching khugepaged to collapse pages in COW mappings, but allocating huge on fault is probably overkill. Signed-off-by: Kirill A. Shutemov --- mm/memory.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/mm/memory.c b/mm/memory.c index 23de0567db18..cba29c033702 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3388,6 +3388,11 @@ static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd) if (fe->vma->vm_ops->pmd_fault) return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd, fe->flags); + + /* COW handled on pte level: split pmd */ + VM_BUG_ON_VMA(fe->vma->vm_flags & VM_SHARED, fe->vma); + split_huge_pmd(fe->vma, fe->pmd, fe->address); + return VM_FAULT_FALLBACK; }