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 2EA72C7EE2F for ; Mon, 12 Jun 2023 20:57:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238731AbjFLU5L (ORCPT ); Mon, 12 Jun 2023 16:57:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47876 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238583AbjFLU4u (ORCPT ); Mon, 12 Jun 2023 16:56:50 -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 9B331E54 for ; Mon, 12 Jun 2023 13:52:37 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 5B02A62150 for ; Mon, 12 Jun 2023 20:50:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF844C433D2; Mon, 12 Jun 2023 20:50:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686603037; bh=+6bWbNlMMY6DSoL9TFRSEX0OALiJJGb4tKRRiWQ49+c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bItv31sJeirjsOFKBsE1dogUy5MHsWfB0+vvt2xRVGFKCPiCIXIgwpCMg7WjwxvzB 2eKvPoQ3X4RbxTdwdexd1N1i7GefSZNsPqf5yOBe/qtqeD3Trgli4BrYVR8fMdboi/ sWe/SED+XUtjw2EhHbM0rdMjqU9+gi9eMvIfamtECeAaxkEPx73mlhyIXGxWKP7G77 2azpPIoNEy42mvgL97b7Zom19DDqX8hpYT40t6dYatHUdBUOqUjr7AlbW+Bpz/LRZd Vp527MQpZNNVIDVBYYHBiY0BahikGz8PMwyXBJS/0/dePSlAQj/8OyUdGg4eV3y9tJ kLoWBlT1ceTfw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 6C1BBCE09E7; Mon, 12 Jun 2023 13:50:37 -0700 (PDT) From: "Paul E. McKenney" To: peterz@infradead.org, jgross@suse.com, vschneid@redhat.com, yury.norov@gmail.com Cc: linux-kernel@vger.kernel.org, imran.f.khan@oracle.com, kernel-team@meta.com, "Paul E . McKenney" Subject: [PATCH csd-lock 1/2] smp: Reduce logging due to dump_stack of CSD waiters Date: Mon, 12 Jun 2023 13:50:35 -0700 Message-Id: <20230612205036.292542-1-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <3ee27fe5-cbea-46b6-adb0-48c4dde92b4f@paulmck-laptop> References: <3ee27fe5-cbea-46b6-adb0-48c4dde92b4f@paulmck-laptop> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Imran Khan If a waiter is waiting for CSD lock, its call stack will not change between first and subsequent hang detection for the same CSD lock. Therefore, do dump_stack only for first-time detection for a given waiter. This avoids excessive logging on systems with hundreds of CPUs where repetitive dump_stack from hundreds of CPUs would otherwise flood the console. Signed-off-by: Imran Khan Cc: Peter Zijlstra Cc: Juergen Gross Cc: Valentin Schneider Cc: Yury Norov Signed-off-by: Paul E. McKenney --- kernel/smp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/smp.c b/kernel/smp.c index ab3e5dad6cfe..b7ccba677a0a 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -248,7 +248,8 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * arch_send_call_function_single_ipi(cpu); } } - dump_stack(); + if (firsttime) + dump_stack(); *ts1 = ts2; return false; -- 2.40.1