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 95D2EC33C9B for ; Tue, 7 Jan 2020 21:14:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 69A822072A for ; Tue, 7 Jan 2020 21:14:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431686; bh=PzOiKsjF1/umswGqVpZDzDrBAh8I1IAG4egqRoftmpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=GF/oxdYFEhE8FMZcHhPHvwe5LG3w4nlHp8zXvV3qHabIznGyGqse5910cnKQz8oZ8 w7xUp/X7Gg9alT+1xrCEiJE2HaAnQu5MGCqvKJaXrwoOiORupRKmCvEnhK9rXsnioy DsokSk1go+MOabLtXPwnFTcXhUK1K8dGjzC1x7MU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730113AbgAGVOp (ORCPT ); Tue, 7 Jan 2020 16:14:45 -0500 Received: from mail.kernel.org ([198.145.29.99]:34080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729782AbgAGVJG (ORCPT ); Tue, 7 Jan 2020 16:09:06 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 B2B572077B; Tue, 7 Jan 2020 21:09:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431345; bh=PzOiKsjF1/umswGqVpZDzDrBAh8I1IAG4egqRoftmpc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dI5chXwr3JsE1n4OYWl64VrmI+BtlS41iLREMjPoikPOoZSU+29bZNEvJOiYltCP+ h5TKhcFZGFOGsw4kiTcUw+6XhLg34FYfSujHC8epcqoOTaEyv5rrnu1r5Nl0a3AoMC W2E0P4qjCsrp0NWFXHgcVHBhqoAyRNV4x+JFiG4w= 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 4.14 19/74] PM / hibernate: memory_bm_find_bit(): Tighten node optimisation Date: Tue, 7 Jan 2020 21:54:44 +0100 Message-Id: <20200107205148.756441076@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107205135.369001641@linuxfoundation.org> References: <20200107205135.369001641@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 0972a8e09d08..ff2aabb70de9 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -734,8 +734,15 @@ 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