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 512A4C04FDF for ; Wed, 2 Aug 2023 07:27:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232378AbjHBH1e (ORCPT ); Wed, 2 Aug 2023 03:27:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230072AbjHBH1c (ORCPT ); Wed, 2 Aug 2023 03:27:32 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 23FFF1999 for ; Wed, 2 Aug 2023 00:27:28 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id CD1151F8A4; Wed, 2 Aug 2023 07:27:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1690961240; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=7QuTI4px0svJS3sCffeA4A0UjcpYXiTrC7fEWOC9D6g=; b=q9GnhUzteZ7WeqCb/K2wNYIOgLHxWaC/qKVjPyIyujnATskvP+Wnb12IBTCJH0m9Te3so/ fK+SnyWvoq8h/gTxMm9+LHM0HothuAIAioO37nxLVKQ4J3bso7UZo+BCNcZsGKEn5MRl+h Vq2WqL/r+hNf1LGM7ABUqFF61o00WXg= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id AABD113909; Wed, 2 Aug 2023 07:27:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id Kg8sJ1gFymQ7HwAAMHmgww (envelope-from ); Wed, 02 Aug 2023 07:27:20 +0000 Date: Wed, 2 Aug 2023 09:27:20 +0200 From: Michal Hocko To: Doug Anderson Cc: Andrew Morton , Petr Mladek , kernel test robot , Lecopzer Chen , Pingfan Liu , linux-kernel@vger.kernel.org Subject: Re: [PATCH] watchdog/hardlockup: Avoid large stack frames in watchdog_hardlockup_check() Message-ID: References: <20230731091754.1.I501ab68cb926ee33a7c87e063d207abf09b9943c@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue 01-08-23 08:41:49, Doug Anderson wrote: [...] > Ah, I see what you mean. The one issue I have with your solution is > that the ordering of the stack crawls is less ideal in the "dump all" > case when cpu != this_cpu. We really want to see the stack crawl of > the locked up CPU first and _then_ see the stack crawls of other CPUs. > With your solution the locked up CPU will be interspersed with all the > others and will be harder to find in the output (you've got to match > it up with the "Watchdog detected hard LOCKUP on cpu N" message). > While that's probably not a huge deal, it's nicer to make the output > easy to understand for someone trying to parse it... Is it worth to waste memory for this arguably nicer output? Identifying the stack of the locked up CPU is trivial. -- Michal Hocko SUSE Labs