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=unavailable 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 3B676C43465 for ; Fri, 18 Sep 2020 02:57:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B04820870 for ; Fri, 18 Sep 2020 02:57:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600397824; bh=hWxEemS0CtcU8+GmrUgxR9sUWie9zveuyVgl/2YQdms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LZiLO3WGfGS0vyuTDwlYzGmyq73S/BLBYMAEGsgzg8nJD/+I+i/42oVuOAe4Qss2h OvJPzxnBE7cY9FZupJZPxlC36wKbmQ25y8+XjafpBWV8tedxOopohsVq8iFhPkQgM1 6zQv/T5N9vrLZMOYKO4y8jeNuTktWO90M0h3oB+4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727902AbgIRC46 (ORCPT ); Thu, 17 Sep 2020 22:56:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:56486 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726573AbgIRCGt (ORCPT ); Thu, 17 Sep 2020 22:06:49 -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 F0B31238E5; Fri, 18 Sep 2020 02:06:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600394803; bh=hWxEemS0CtcU8+GmrUgxR9sUWie9zveuyVgl/2YQdms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Jc9f+nCQFXXFqKUYGhS4trw59OWh14hNnCO/GUrtuQzwFKo293uGLLhhFGdoMPhWP CE1pIDE8uVl7MkhM5n8Uu9To30MmtGVwGIcd6/F+pwPVfr8mgKzRInhC1UCEN7emLz 0My3ldMazIDtqzWZs6yW1/a09gyt6L6Pp+vqwY3I= 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 5.4 272/330] fuse: don't check refcount after stealing page Date: Thu, 17 Sep 2020 22:00:12 -0400 Message-Id: <20200918020110.2063155-272-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org> References: <20200918020110.2063155-1-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 06dd38e76c62a..f9022b7028754 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -764,7 +764,6 @@ 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