From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A0EC1C43464 for ; Fri, 18 Sep 2020 02:25:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6139822211 for ; Fri, 18 Sep 2020 02:25:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395909; bh=hW6fRqiJnoP0f/soN1MX0TjBN2a7bTw19nIOCeIaSt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dnba3reL3da3u7K58i9CewzG2D8c4aH4VOJ+cGJ8/QPCjqVvHcX5ccJbgzNOeZ0r1 UO5QdvUyyjzHCZdP9w6sB2uoZI5VFT8vYssqYlpU34YB8NpPjuSujzdwpKYMxtxjit 5eZNm8RXexshg5VQ3tLzEgBmTnfkJoIcqx3ZkzDg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729812AbgIRCZI (ORCPT ); Thu, 17 Sep 2020 22:25:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:46076 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729398AbgIRCQY (ORCPT ); Thu, 17 Sep 2020 22:16:24 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9D9FA23787; Fri, 18 Sep 2020 02:16:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600395384; bh=hW6fRqiJnoP0f/soN1MX0TjBN2a7bTw19nIOCeIaSt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=pPvbVm3Qpr5+0jD79tIkHRts26zDPXG0rAuR5I2hYMZ+x7OVcdF/DAUnPxWPVxLYo IUVCrYP9JuoMnd/dVZ/kaotYfUFu/PAd9Ee7RjgZiPRXghs7E2FEJtL5lG4T7ZsPm6 BK/vc57z+4nmSyMkcwREPEExrlnhV0CpIVPVEGw8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Miklos Szeredi , Matthew Wilcox , Sasha Levin , fuse-devel@lists.sourceforge.net Subject: [PATCH AUTOSEL 4.9 75/90] fuse: don't check refcount after stealing page Date: Thu, 17 Sep 2020 22:14:40 -0400 Message-Id: <20200918021455.2067301-75-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918021455.2067301-1-sashal@kernel.org> References: <20200918021455.2067301-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi [ Upstream commit 32f98877c57bee6bc27f443a96f49678a2cd6a50 ] page_count() is unstable. Unless there has been an RCU grace period between when the page was removed from the page cache and now, a speculative reference may exist from the page cache. Reported-by: Matthew Wilcox Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin --- fs/fuse/dev.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index b99225e117120..f0129c033bd66 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -825,7 +825,6 @@ static int fuse_check_page(struct page *page) { if (page_mapcount(page) || page->mapping != NULL || - page_count(page) != 1 || (page->flags & PAGE_FLAGS_CHECK_AT_PREP & ~(1 << PG_locked | 1 << PG_referenced | -- 2.25.1