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 7617AC433F5 for ; Mon, 18 Apr 2022 14:17:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344095AbiDROUg (ORCPT ); Mon, 18 Apr 2022 10:20:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37142 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344984AbiDROSj (ORCPT ); Mon, 18 Apr 2022 10:18:39 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 94B234BB92; Mon, 18 Apr 2022 06:14:26 -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 ams.source.kernel.org (Postfix) with ESMTPS id 041C3B80EC0; Mon, 18 Apr 2022 13:13:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CF04C385A1; Mon, 18 Apr 2022 13:13:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650287637; bh=jlbYAnne9Y+hPCHXuiK/M0vgClZgsk1PxnfMkIar79I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=naUnvBqPP0M8F9rX96Qg4zuizsA3TKAJUUQ4Uj2Z3S624XXUDZDy0A/K/8C7SuGt8 kvMHSuiotGq5J0ECL8XNi2OPIJy2D4/AA+1HVaMts1SlUfqdUNEt1lF7mwt8eSYCfZ uWWUYOjMM/XwX14LvPFeEwENujLeCw3mkG0SVKRw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nadav Amit , Thomas Gleixner Subject: [PATCH 4.9 216/218] smp: Fix offline cpu check in flush_smp_call_function_queue() Date: Mon, 18 Apr 2022 14:14:42 +0200 Message-Id: <20220418121208.532799769@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121158.636999985@linuxfoundation.org> References: <20220418121158.636999985@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nadav Amit commit 9e949a3886356fe9112c6f6f34a6e23d1d35407f upstream. The check in flush_smp_call_function_queue() for callbacks that are sent to offline CPUs currently checks whether the queue is empty. However, flush_smp_call_function_queue() has just deleted all the callbacks from the queue and moved all the entries into a local list. This checks would only be positive if some callbacks were added in the short time after llist_del_all() was called. This does not seem to be the intention of this check. Change the check to look at the local list to which the entries were moved instead of the queue from which all the callbacks were just removed. Fixes: 8d056c48e4862 ("CPU hotplug, smp: flush any pending IPI callbacks before CPU offline") Signed-off-by: Nadav Amit Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20220319072015.1495036-1-namit@vmware.com Signed-off-by: Greg Kroah-Hartman --- kernel/smp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/smp.c +++ b/kernel/smp.c @@ -209,7 +209,7 @@ static void flush_smp_call_function_queu /* There shouldn't be any pending callbacks on an offline CPU. */ if (unlikely(warn_cpu_offline && !cpu_online(smp_processor_id()) && - !warned && !llist_empty(head))) { + !warned && entry != NULL)) { warned = true; WARN(1, "IPI on offline CPU %d\n", smp_processor_id());