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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3450C77B6F for ; Tue, 11 Apr 2023 13:48:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229920AbjDKNsE (ORCPT ); Tue, 11 Apr 2023 09:48:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230468AbjDKNr6 (ORCPT ); Tue, 11 Apr 2023 09:47:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 618505263 for ; Tue, 11 Apr 2023 06:47:42 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 97DAA620A1 for ; Tue, 11 Apr 2023 13:47:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC37AC433D2; Tue, 11 Apr 2023 13:47:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681220858; bh=+uZW0vXAk8wIfog/MTLW635WGPH/DPqt5eUq/QpD7po=; h=Subject:To:Cc:From:Date:From; b=n3NSxYfT3Im0sSqLG3gCjZxfXgaLzxx1eYJ6eXlVrjAAph/OLKYAg5GDN+YOjsIL2 xLTmMhxLR2VxnRsqClzLUesgeoGgyG6tEFXSFFHu2kC4tRP9i39b1+lfU62oD3QzcQ BR9n3ickeKhn8sx8NLIl21wo4ydWiUbsg1AbBxU4= Subject: FAILED: patch "[PATCH] maple_tree: add smp_rmb() to dead node detection" failed to apply to 6.2-stable tree To: Liam.Howlett@oracle.com, akpm@linux-foundation.org, stable@vger.kernel.org, surenb@google.com Cc: From: Date: Tue, 11 Apr 2023 15:47:33 +0200 Message-ID: <2023041133-corroding-underdone-8e9f@gregkh> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 6.2-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.2.y git checkout FETCH_HEAD git cherry-pick -x 0a2b18d948838e16912b3b627b504ab062b7d02a # git commit -s git send-email --to '' --in-reply-to '2023041133-corroding-underdone-8e9f@gregkh' --subject-prefix 'PATCH 6.2.y' HEAD^.. Possible dependencies: 0a2b18d94883 ("maple_tree: add smp_rmb() to dead node detection") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 0a2b18d948838e16912b3b627b504ab062b7d02a Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Mon, 27 Feb 2023 09:36:05 -0800 Subject: [PATCH] maple_tree: add smp_rmb() to dead node detection Add an smp_rmb() before reading the parent pointer to ensure that anything read from the node prior to the parent pointer hasn't been reordered ahead of this check. The is necessary for RCU mode. Link: https://lkml.kernel.org/r/20230227173632.3292573-7-surenb@google.com Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Signed-off-by: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 5202d89ba56e..72c89eb03393 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -539,9 +539,11 @@ static inline struct maple_node *mte_parent(const struct maple_enode *enode) */ static inline bool ma_dead_node(const struct maple_node *node) { - struct maple_node *parent = (void *)((unsigned long) - node->parent & ~MAPLE_NODE_MASK); + struct maple_node *parent; + /* Do not reorder reads from the node prior to the parent check */ + smp_rmb(); + parent = (void *)((unsigned long) node->parent & ~MAPLE_NODE_MASK); return (parent == node); } @@ -556,6 +558,8 @@ static inline bool mte_dead_node(const struct maple_enode *enode) struct maple_node *parent, *node; node = mte_to_node(enode); + /* Do not reorder reads from the node prior to the parent check */ + smp_rmb(); parent = mte_parent(enode); return (parent == node); }