From patchwork Fri Aug 7 11:53:43 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Kirill A . Shutemov" X-Patchwork-Id: 6968421 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 70D11C05AC for ; Fri, 7 Aug 2015 11:54:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 8838F20603 for ; Fri, 7 Aug 2015 11:54:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9EAAD205FA for ; Fri, 7 Aug 2015 11:54:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752661AbbHGLyV (ORCPT ); Fri, 7 Aug 2015 07:54:21 -0400 Received: from mga09.intel.com ([134.134.136.24]:51156 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752140AbbHGLyU (ORCPT ); Fri, 7 Aug 2015 07:54:20 -0400 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP; 07 Aug 2015 04:54:20 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,629,1432623600"; d="scan'208";a="763968079" Received: from black.fi.intel.com ([10.237.72.157]) by fmsmga001.fm.intel.com with ESMTP; 07 Aug 2015 04:54:18 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id 7359123D; Fri, 7 Aug 2015 14:53:47 +0300 (EEST) From: "Kirill A. Shutemov" To: Andrew Morton , Matthew Wilcox Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCH] mm: take i_mmap_lock in unmap_mapping_range() for DAX Date: Fri, 7 Aug 2015 14:53:43 +0300 Message-Id: <1438948423-128882-1-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.4.6 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-7.0 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 DAX is not so special: we need i_mmap_lock to protect mapping->i_mmap. __dax_pmd_fault() uses unmap_mapping_range() shoot out zero page from all mappings. We need to drop i_mmap_lock there to avoid lock deadlock. Re-aquiring the lock should be fine since we check i_size after the point. Not-yet-signed-off-by: Matthew Wilcox Signed-off-by: Kirill A. Shutemov --- fs/dax.c | 35 +++++++++++++++++++---------------- mm/memory.c | 11 ++--------- 2 files changed, 21 insertions(+), 25 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 9ef9b80cc132..ed54efedade6 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -554,6 +554,25 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if (!buffer_size_valid(&bh) || bh.b_size < PMD_SIZE) goto fallback; + if (buffer_unwritten(&bh) || buffer_new(&bh)) { + int i; + for (i = 0; i < PTRS_PER_PMD; i++) + clear_page(kaddr + i * PAGE_SIZE); + count_vm_event(PGMAJFAULT); + mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); + result |= VM_FAULT_MAJOR; + } + + /* + * If we allocated new storage, make sure no process has any + * zero pages covering this hole + */ + if (buffer_new(&bh)) { + i_mmap_unlock_write(mapping); + unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); + i_mmap_lock_write(mapping); + } + /* * If a truncate happened while we were allocating blocks, we may * leave blocks allocated to the file that are beyond EOF. We can't @@ -568,13 +587,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if ((pgoff | PG_PMD_COLOUR) >= size) goto fallback; - /* - * If we allocated new storage, make sure no process has any - * zero pages covering this hole - */ - if (buffer_new(&bh)) - unmap_mapping_range(mapping, pgoff << PAGE_SHIFT, PMD_SIZE, 0); - if (!write && !buffer_mapped(&bh) && buffer_uptodate(&bh)) { spinlock_t *ptl; pmd_t entry; @@ -605,15 +617,6 @@ int __dax_pmd_fault(struct vm_area_struct *vma, unsigned long address, if ((length < PMD_SIZE) || (pfn & PG_PMD_COLOUR)) goto fallback; - if (buffer_unwritten(&bh) || buffer_new(&bh)) { - int i; - for (i = 0; i < PTRS_PER_PMD; i++) - clear_page(kaddr + i * PAGE_SIZE); - count_vm_event(PGMAJFAULT); - mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); - result |= VM_FAULT_MAJOR; - } - result |= vmf_insert_pfn_pmd(vma, address, pmd, pfn, write); } diff --git a/mm/memory.c b/mm/memory.c index 5a3427bb3f32..670cdfa9f33e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2426,17 +2426,10 @@ void unmap_mapping_range(struct address_space *mapping, if (details.last_index < details.first_index) details.last_index = ULONG_MAX; - - /* - * DAX already holds i_mmap_lock to serialise file truncate vs - * page fault and page fault vs page fault. - */ - if (!IS_DAX(mapping->host)) - i_mmap_lock_write(mapping); + i_mmap_lock_write(mapping); if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) unmap_mapping_range_tree(&mapping->i_mmap, &details); - if (!IS_DAX(mapping->host)) - i_mmap_unlock_write(mapping); + i_mmap_unlock_write(mapping); } EXPORT_SYMBOL(unmap_mapping_range);