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 0CA46C433EF for ; Mon, 18 Apr 2022 12:31:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239081AbiDRMeK (ORCPT ); Mon, 18 Apr 2022 08:34:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239765AbiDRMdY (ORCPT ); Mon, 18 Apr 2022 08:33:24 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E1ACB1EACE; Mon, 18 Apr 2022 05:25:37 -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 99B9AB80ED6; Mon, 18 Apr 2022 12:25:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9092C385A1; Mon, 18 Apr 2022 12:25:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650284735; bh=OheKLmfXH/0ETv6AsmLPpvnGotO5nZR5o2vxS0ci7Fg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AuwHufPjomyMb7lTLMdJDK5W8CyJtiihdnkkgtjTbEH8IS0JYBueWurCvWxCSdsGY A79ZAmkL708y02glhaqlpseGH2PSv1l/GNHmA05mknGcwcQKVQOuxd0C2Fk63NYS23 WPtBiYjyqbmLCMAawBTYyIC2nluQHw6umQZLhkE4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nadav Amit , Thomas Gleixner Subject: [PATCH 5.17 210/219] smp: Fix offline cpu check in flush_smp_call_function_queue() Date: Mon, 18 Apr 2022 14:12:59 +0200 Message-Id: <20220418121212.746298475@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121203.462784814@linuxfoundation.org> References: <20220418121203.462784814@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 @@ -579,7 +579,7 @@ 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());