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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 86E0EC33C9E for ; Sat, 11 Jan 2020 10:00:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DE452077C for ; Sat, 11 Jan 2020 10:00:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578736824; bh=J5k4I5PjDOISQmUJ+K3wvYYqJ/TLF/0wPiYvQi9KZAA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i4vdGMrHaotdcqOghmDcu/shA5ToYqcvk/SE11Tp7KuPDJNYNBXkBBii7jvv6GN72 GQcuS3yko2v3RGFHgTLIgglHUSykmsfooDK2ylp7SBTC6M4Z6hVfldPRRZNDz71hnY Z2s1Wx2aDxUK1cIvoP9vq9Nnzyu2RFEeiVYwuPvM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729008AbgAKKAW (ORCPT ); Sat, 11 Jan 2020 05:00:22 -0500 Received: from mail.kernel.org ([198.145.29.99]:56368 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728991AbgAKKAV (ORCPT ); Sat, 11 Jan 2020 05:00:21 -0500 Received: from localhost (unknown [62.119.166.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E26222077C; Sat, 11 Jan 2020 10:00:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578736820; bh=J5k4I5PjDOISQmUJ+K3wvYYqJ/TLF/0wPiYvQi9KZAA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EizOxTpT1H3WTSyMQKaCyEPKQBqaKYYFr4/dvtC72Qg9PdJKQ7P0Y0d1IlIQm17Lq a/Fnhd+5Z3//bYMnOygNuSrQcUh+6yj3s+9alecWMc+X5ajJlajchCRoeYQpMOsMfH 7bFrjniYLmtHx4Shak0Czp/texS0tUuARYMGPr+A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andrea Righi , Andy Whitcroft , "Rafael J. Wysocki" , Sasha Levin Subject: [PATCH 4.9 14/91] PM / hibernate: memory_bm_find_bit(): Tighten node optimisation Date: Sat, 11 Jan 2020 10:49:07 +0100 Message-Id: <20200111094848.319826655@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200111094844.748507863@linuxfoundation.org> References: <20200111094844.748507863@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andy Whitcroft [ Upstream commit da6043fe85eb5ec621e34a92540735dcebbea134 ] When looking for a bit by number we make use of the cached result from the preceding lookup to speed up operation. Firstly we check if the requested pfn is within the cached zone and if not lookup the new zone. We then check if the offset for that pfn falls within the existing cached node. This happens regardless of whether the node is within the zone we are now scanning. With certain memory layouts it is possible for this to false trigger creating a temporary alias for the pfn to a different bit. This leads the hibernation code to free memory which it was never allocated with the expected fallout. Ensure the zone we are scanning matches the cached zone before considering the cached node. Deep thanks go to Andrea for many, many, many hours of hacking and testing that went into cornering this bug. Reported-by: Andrea Righi Tested-by: Andrea Righi Signed-off-by: Andy Whitcroft Signed-off-by: Rafael J. Wysocki Signed-off-by: Sasha Levin --- kernel/power/snapshot.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 4f0f0604f1c4..5dfac92521fa 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -732,8 +732,15 @@ static int memory_bm_find_bit(struct memory_bitmap *bm, unsigned long pfn, * We have found the zone. Now walk the radix tree to find the leaf node * for our PFN. */ + + /* + * If the zone we wish to scan is the the current zone and the + * pfn falls into the current node then we do not need to walk + * the tree. + */ node = bm->cur.node; - if (((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn) + if (zone == bm->cur.zone && + ((pfn - zone->start_pfn) & ~BM_BLOCK_MASK) == bm->cur.node_pfn) goto node_found; node = zone->rtree; -- 2.20.1