From patchwork Mon Mar 21 13:22:52 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 8632771 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 95016C0554 for ; Mon, 21 Mar 2016 13:22:40 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id BF0BA201EF for ; Mon, 21 Mar 2016 13:22:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C611020304 for ; Mon, 21 Mar 2016 13:22:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755466AbcCUNWf (ORCPT ); Mon, 21 Mar 2016 09:22:35 -0400 Received: from mx2.suse.de ([195.135.220.15]:51712 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755146AbcCUNWd (ORCPT ); Mon, 21 Mar 2016 09:22:33 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 06A71AD22; Mon, 21 Mar 2016 13:22:31 +0000 (UTC) Received: by quack.suse.cz (Postfix, from userid 1000) id C482882525; Mon, 21 Mar 2016 14:22:58 +0100 (CET) From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: "Wilcox, Matthew R" , Ross Zwisler , Dan Williams , linux-nvdimm@lists.01.org, NeilBrown , Jan Kara Subject: [PATCH 07/10] dax: Disable huge page handling Date: Mon, 21 Mar 2016 14:22:52 +0100 Message-Id: <1458566575-28063-8-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1458566575-28063-1-git-send-email-jack@suse.cz> References: <1458566575-28063-1-git-send-email-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Spam-Status: No, score=-6.9 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 Currently the handling of huge pages for DAX is racy. For example the following can happen: CPU0 (THP write fault) CPU1 (normal read fault) __dax_pmd_fault() __dax_fault() get_block(inode, block, &bh, 0) -> not mapped get_block(inode, block, &bh, 0) -> not mapped if (!buffer_mapped(&bh) && write) get_block(inode, block, &bh, 1) -> allocates blocks truncate_pagecache_range(inode, lstart, lend); dax_load_hole(); This results in data corruption since process on CPU1 won't see changes into the file done by CPU0. The race can happen even if two normal faults race however with THP the situation is even worse because the two faults don't operate on the same entries in the radix tree and we want to use these entries for serialization. So disable THP support in DAX code for now. Signed-off-by: Jan Kara --- fs/dax.c | 2 +- include/linux/dax.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/dax.c b/fs/dax.c index 0329ec0bee2e..444e9dd079ca 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -719,7 +719,7 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, } EXPORT_SYMBOL_GPL(dax_fault); -#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#if 0 /* * The 'colour' (ie low bits) within a PMD of a page offset. This comes up * more often than one might expect in the below function. diff --git a/include/linux/dax.h b/include/linux/dax.h index 4b63923e1f8d..fd28d824254b 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -29,7 +29,7 @@ static inline struct page *read_dax_sector(struct block_device *bdev, } #endif -#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#if 0 int dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *, unsigned int flags, get_block_t); int __dax_pmd_fault(struct vm_area_struct *, unsigned long addr, pmd_t *,