From patchwork Fri Aug 12 18:37:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A . Shutemov" X-Patchwork-Id: 9277611 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id F1D1560780 for ; Fri, 12 Aug 2016 18:39:43 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E6E1628AA6 for ; Fri, 12 Aug 2016 18:39:43 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id DB74E28AD2; Fri, 12 Aug 2016 18:39:43 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8C67728AA6 for ; Fri, 12 Aug 2016 18:39:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752924AbcHLSjK (ORCPT ); Fri, 12 Aug 2016 14:39:10 -0400 Received: from mga14.intel.com ([192.55.52.115]:28738 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752921AbcHLSjI (ORCPT ); Fri, 12 Aug 2016 14:39:08 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 12 Aug 2016 11:38:44 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,512,1464678000"; d="scan'208";a="1024497183" Received: from black.fi.intel.com ([10.237.72.93]) by fmsmga001.fm.intel.com with ESMTP; 12 Aug 2016 11:38:40 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id D5E703B6; Fri, 12 Aug 2016 21:38:33 +0300 (EEST) From: "Kirill A. Shutemov" To: "Theodore Ts'o" , Andreas Dilger , Jan Kara , Andrew Morton Cc: Alexander Viro , Hugh Dickins , Andrea Arcangeli , Dave Hansen , Vlastimil Babka , Matthew Wilcox , Ross Zwisler , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv2 12/41] thp: handle write-protection faults for file THP Date: Fri, 12 Aug 2016 21:37:55 +0300 Message-Id: <1471027104-115213-13-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.8.1 In-Reply-To: <1471027104-115213-1-git-send-email-kirill.shutemov@linux.intel.com> References: <1471027104-115213-1-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-Virus-Scanned: ClamAV using ClamSMTP For filesystems that wants to be write-notified (has mkwrite), we will encount write-protection faults for huge PMDs in shared mappings. The easiest way to handle them is to clear the PMD and let it refault as wriable. Signed-off-by: Kirill A. Shutemov --- mm/memory.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/memory.c b/mm/memory.c index 4425b6059339..5b7f0ce44a27 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3448,8 +3448,17 @@ static int wp_huge_pmd(struct fault_env *fe, pmd_t orig_pmd) return fe->vma->vm_ops->pmd_fault(fe->vma, fe->address, fe->pmd, fe->flags); + if (fe->vma->vm_flags & VM_SHARED) { + /* Clear PMD */ + zap_page_range_single(fe->vma, fe->address, + HPAGE_PMD_SIZE, NULL); + VM_BUG_ON(!pmd_none(*fe->pmd)); + + /* Refault to establish writable PMD */ + return 0; + } + /* 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;