From patchwork Thu Mar 10 19:18:54 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 8559621 Return-Path: X-Original-To: patchwork-linux-nvdimm@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 0ACFAC0554 for ; Thu, 10 Mar 2016 19:18:45 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 23A6120386 for ; Thu, 10 Mar 2016 19:18:44 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 385B920377 for ; Thu, 10 Mar 2016 19:18:43 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id A0C001A1F73; Thu, 10 Mar 2016 11:18:57 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 45D4C1A1F5F for ; Thu, 10 Mar 2016 11:18:54 -0800 (PST) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 59907ACCC; Thu, 10 Mar 2016 19:18:36 +0000 (UTC) Received: by quack.suse.cz (Postfix, from userid 1000) id 4B2D082529; Thu, 10 Mar 2016 20:18:57 +0100 (CET) From: Jan Kara To: linux-fsdevel@vger.kernel.org Subject: [PATCH 11/12] dax: Disable huge page handling Date: Thu, 10 Mar 2016 20:18:54 +0100 Message-Id: <1457637535-21633-12-git-send-email-jack@suse.cz> X-Mailer: git-send-email 2.6.2 In-Reply-To: <1457637535-21633-1-git-send-email-jack@suse.cz> References: <1457637535-21633-1-git-send-email-jack@suse.cz> Cc: Jan Kara , linux-nvdimm@lists.01.org, NeilBrown , "Wilcox, Matthew R" X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, 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 3951237ff248..7148fcdb2c92 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -715,7 +715,7 @@ 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 *,