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 944C5C433EF for ; Mon, 18 Apr 2022 12:53:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238386AbiDRMz7 (ORCPT ); Mon, 18 Apr 2022 08:55:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240308AbiDRMzK (ORCPT ); Mon, 18 Apr 2022 08:55:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D9D8B764F; Mon, 18 Apr 2022 05:36:21 -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 74DB461033; Mon, 18 Apr 2022 12:36:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69EC2C385A7; Mon, 18 Apr 2022 12:36:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1650285380; bh=OheKLmfXH/0ETv6AsmLPpvnGotO5nZR5o2vxS0ci7Fg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=STXlt6fljl6e5zLUIR7nH75gYgpMFD51hdTKuvQXLLWEp7NoqwiYUTe9veAC2znKR BUG7JE1JTC/jNM76KiEHZsXZdc78XBC/8pTU10VGINF1gsBw1PsqqXUGClmGwTIwYc x6RtZ5BkoQ+nhgKcK5xfrzNZnv82QCA+ShJH0ueg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nadav Amit , Thomas Gleixner Subject: [PATCH 5.15 172/189] smp: Fix offline cpu check in flush_smp_call_function_queue() Date: Mon, 18 Apr 2022 14:13:12 +0200 Message-Id: <20220418121207.655441253@linuxfoundation.org> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220418121200.312988959@linuxfoundation.org> References: <20220418121200.312988959@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());