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 184F2C7EE23 for ; Fri, 19 May 2023 21:28:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229523AbjESV25 (ORCPT ); Fri, 19 May 2023 17:28:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229449AbjESV2y (ORCPT ); Fri, 19 May 2023 17:28:54 -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 443D9BC for ; Fri, 19 May 2023 14:28:53 -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 C13E465788 for ; Fri, 19 May 2023 21:28:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 207DFC433EF; Fri, 19 May 2023 21:28:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1684531732; bh=OhGB8Cxhp/VimtTSIzObKbHxF5LenY6X3FcljzNzYA8=; h=Date:To:From:Subject:From; b=CCx/Opij4JnZ49GkSoaQAfR/A52DYUbk/q+2H5yWLFzWCSdQ/lHZbMUTNouc2q15m kPVCb9c18R5cvG72srZtGLe+lWG1HSvGBqI1kzNcmoOuz/VMRIEf2af+uAbjdts13J UkF0DWkO/0omUaHDZoCiupCqOC31K/EOrcwLx5Vk= Date: Fri, 19 May 2023 14:28:51 -0700 To: mm-commits@vger.kernel.org, will@kernel.org, wens@csie.org, tzungbi@chromium.org, swboyd@chromium.org, sumit.garg@linaro.org, ricardo.neri@intel.com, rdunlap@infradead.org, ravi.v.shankar@intel.com, pmladek@suse.com, npiggin@gmail.com, msys.mizuma@gmail.com, mpe@ellerman.id.au, mka@chromium.org, maz@kernel.org, mark.rutland@arm.com, lecopzer.chen@mediatek.com, kernelfans@gmail.com, irogers@google.com, groeck@chromium.org, eranian@google.com, davem@davemloft.net, daniel.thompson@linaro.org, christophe.leroy@csgroup.eu, ccross@android.com, catalin.marinas@arm.com, ak@linux.intel.com, dianders@chromium.org, akpm@linux-foundation.org From: Andrew Morton Subject: + watchdog-perf-more-properly-prevent-false-positives-with-turbo-modes.patch added to mm-nonmm-unstable branch Message-Id: <20230519212852.207DFC433EF@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: watchdog/perf: more properly prevent false positives with turbo modes has been added to the -mm mm-nonmm-unstable branch. Its filename is watchdog-perf-more-properly-prevent-false-positives-with-turbo-modes.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/watchdog-perf-more-properly-prevent-false-positives-with-turbo-modes.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Douglas Anderson Subject: watchdog/perf: more properly prevent false positives with turbo modes Date: Fri, 19 May 2023 10:18:26 -0700 Currently, in the watchdog_overflow_callback() we first check to see if the watchdog had been touched and _then_ we handle the workaround for turbo mode. This order should be reversed. Specifically, "touching" the hardlockup detector's watchdog should avoid lockups being detected for one period that should be roughly the same regardless of whether we're running turbo or not. That means that we should do the extra accounting for turbo _before_ we look at (and clear) the global indicating that we've been touched. NOTE: this fix is made based on code inspection. I am not aware of any reports where the old code would have generated false positives. That being said, this order seems more correct and also makes it easier down the line to share code with the "buddy" hardlockup detector. Link: https://lkml.kernel.org/r/20230519101840.v5.2.I843b0d1de3e096ba111a179f3adb16d576bef5c7@changeid Fixes: 7edaeb6841df ("kernel/watchdog: Prevent false positives with turbo modes") Signed-off-by: Douglas Anderson Cc: Andi Kleen Cc: Catalin Marinas Cc: Chen-Yu Tsai Cc: Christophe Leroy Cc: Colin Cross Cc: Daniel Thompson Cc: "David S. Miller" Cc: Guenter Roeck Cc: Ian Rogers Cc: Lecopzer Chen Cc: Marc Zyngier Cc: Mark Rutland Cc: Masayoshi Mizuma Cc: Matthias Kaehlcke Cc: Michael Ellerman Cc: Nicholas Piggin Cc: Petr Mladek Cc: Pingfan Liu Cc: Randy Dunlap Cc: "Ravi V. Shankar" Cc: Ricardo Neri Cc: Stephane Eranian Cc: Stephen Boyd Cc: Sumit Garg Cc: Tzung-Bi Shih Cc: Will Deacon Signed-off-by: Andrew Morton --- kernel/watchdog_hld.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/watchdog_hld.c~watchdog-perf-more-properly-prevent-false-positives-with-turbo-modes +++ a/kernel/watchdog_hld.c @@ -114,14 +114,14 @@ static void watchdog_overflow_callback(s /* Ensure the watchdog never gets throttled */ event->hw.interrupts = 0; + if (!watchdog_check_timestamp()) + return; + if (__this_cpu_read(watchdog_nmi_touch) == true) { __this_cpu_write(watchdog_nmi_touch, false); return; } - if (!watchdog_check_timestamp()) - return; - /* check for a hardlockup * This is done by making sure our timer interrupt * is incrementing. The timer interrupt should have _ Patches currently in -mm which might be from dianders@chromium.org are migrate_pages-avoid-blocking-for-io-in-migrate_sync_light.patch watchdog-perf-define-dummy-watchdog_update_hrtimer_threshold-on-correct-config.patch watchdog-perf-more-properly-prevent-false-positives-with-turbo-modes.patch watchdog-hardlockup-add-comments-to-touch_nmi_watchdog.patch watchdog-perf-rename-watchdog_hldc-to-watchdog_perfc.patch watchdog-hardlockup-move-perf-hardlockup-checking-panic-to-common-watchdogc.patch watchdog-hardlockup-style-changes-to-watchdog_hardlockup_check-is_hardlockup.patch watchdog-hardlockup-add-a-cpu-param-to-watchdog_hardlockup_check.patch watchdog-hardlockup-move-perf-hardlockup-watchdog-petting-to-watchdogc.patch watchdog-hardlockup-rename-some-nmi-watchdog-constants-function.patch watchdog-hardlockup-have-the-perf-hardlockup-use-__weak-functions-more-cleanly.patch watchdog-hardlockup-detect-hard-lockups-using-secondary-buddy-cpus.patch watchdog-perf-add-a-weak-function-for-an-arch-to-detect-if-perf-can-use-nmis.patch arm64-enable-perf-events-based-hard-lockup-detector.patch