From patchwork Tue Nov 27 21:16:33 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 10701439 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D41D7109C for ; Tue, 27 Nov 2018 21:16:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C2E082B3A5 for ; Tue, 27 Nov 2018 21:16:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B720A2B49D; Tue, 27 Nov 2018 21:16:51 +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=-2.7 required=2.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 50B952B3A5 for ; Tue, 27 Nov 2018 21:16:51 +0000 (UTC) Received: from [127.0.0.1] (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 1E6242119309E; Tue, 27 Nov 2018 13:16:51 -0800 (PST) X-Original-To: linux-nvdimm@lists.01.org Delivered-To: linux-nvdimm@lists.01.org Received-SPF: None (no SPF record) identity=mailfrom; client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=willy@infradead.org; receiver=linux-nvdimm@lists.01.org Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id F1DC62119309E for ; Tue, 27 Nov 2018 13:16:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=References:In-Reply-To:Message-Id: Date:Subject:Cc:To:From:Sender:Reply-To:MIME-Version:Content-Type: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=OT1rLectPsqnpoX38b5gmExIoodFcyMH7TxgRaRoKWk=; b=mNl7qObxx93XmALMsbxDLTZzb /LVNM0Sqxm8s0DuJeO4HpK08mFvPilqQfThYTUTWo/0+x+fQHcWyVMOpu7AhHw9jJcKVR4/c9jJc5 audhzbqFEN3iIu6IupClUlm00Zi9d8o3jx8b4BItq8ORwmZWoPGhmR+B3oJUp/caVowaewTOf7KeK xg0pVkAAe27dCFcs+cKpG3D4A+xUi4zj9bd4a3xR5EW62ROyST/kwigFQ7+JEt9z1RjGdkbwYzZdz HjsKA1dBAQKmXvD99rck7ecDYN0YJfqut/AUNH6Ncsc1HBvz+bwSlWkBDIrIGn3450R4Yv494LjE6 hPQUcnYkA==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gRkir-0001OL-Qm; Tue, 27 Nov 2018 21:16:45 +0000 From: Matthew Wilcox To: Dan Williams Subject: [PATCH 1/2] dax: Check page->mapping isn't NULL Date: Tue, 27 Nov 2018 13:16:33 -0800 Message-Id: <20181127211634.4995-2-willy@infradead.org> X-Mailer: git-send-email 2.14.5 In-Reply-To: <20181127211634.4995-1-willy@infradead.org> References: <20181127211634.4995-1-willy@infradead.org> X-BeenThere: linux-nvdimm@lists.01.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Linux-nvdimm developer list." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-nvdimm@lists.01.org, stable@vger.kernel.org, Matthew Wilcox , linux-fsdevel@vger.kernel.org, Jan Kara MIME-Version: 1.0 Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" X-Virus-Scanned: ClamAV using ClamSMTP If we race with inode destroy, it's possible for page->mapping to be NULL before we even enter this routine, as well as after having slept waiting for the dax entry to become unlocked. Fixes: c2a7d2a11552 ("filesystem-dax: Introduce dax_lock_mapping_entry()") Cc: stable@vger.kernel.org Reported-by: Jan Kara Signed-off-by: Matthew Wilcox Reviewed-by: Johannes Thumshirn Reviewed-by: Jan Kara --- fs/dax.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 9bcce89ea18e..e69fc231833b 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -365,7 +365,7 @@ bool dax_lock_mapping_entry(struct page *page) struct address_space *mapping = READ_ONCE(page->mapping); locked = false; - if (!dax_mapping(mapping)) + if (!mapping || !dax_mapping(mapping)) break; /*