From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DCF873019B2 for ; Sun, 8 Feb 2026 08:14:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770538461; cv=none; b=M4ttFKoxwE0NzmNU7AxfzWlQDLLns7/wpWQlgg3C/wMgs5yYBOyFkb7ybI8uDVOdy9g8o44ag2C3e95bxQBfIMsJY53vXybfUZXrk2O8jgo3xoeH3/qVEDCXiL0wMgGQVc0/ehyQs10XTgUf4D1V5oAQWyoj0t+/6Hzm5F0w7os= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770538461; c=relaxed/simple; bh=+36Hwcg0wFPVeDUw2Ln0UvCyB/LouusOEJgzjkjBfPw=; h=Date:To:From:Subject:Message-Id; b=maeH2sxlYM8BByrRojYghKntHRmKg1QPv7hdNrl81LxfkzCE4xjHNCSnLIr8aMR90hUR5JDJzSFDno2TO2nOtj5ibjqJsSsuXkR011THdYI6VjBGHaju77cZEnMKGeH7xiTvHe56q+xio01KbSEmCq0zVAmuNQHDNjw3vR19fbk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=zmKMdnnq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="zmKMdnnq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ACAAEC4CEF7; Sun, 8 Feb 2026 08:14:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1770538461; bh=+36Hwcg0wFPVeDUw2Ln0UvCyB/LouusOEJgzjkjBfPw=; h=Date:To:From:Subject:From; b=zmKMdnnqosWOkGwQk5qKxMPkiBuvXQbJDsXtTrrQhJXVRC3OXRNuNkvF3j+XncMIb pP5lK7FN7EdDwvRxh71bk6mBzPigGQCxk4PFoJO6vdMAmrqKgbAwdLTyu1nF8qKUkS 14p/UowmNZ5Le+Wlp/CfCPKAjk6nrOUFv5LwP8CI= Date: Sun, 08 Feb 2026 00:14:21 -0800 To: mm-commits@vger.kernel.org,zhangjn11@chinatelecom.cn,yuanql9@chinatelecom.cn,yangyicong@hisilicon.com,wangjinchao600@gmail.com,thorsten.blum@linux.dev,sunshx@chinatelecom.cn,song@kernel.org,mingo@kernel.org,lihuafei1@huawei.com,dianders@chromium.org,realwujing@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-nonmm-stable] watchdog-hardlockup-simplify-perf-event-probe-and-remove-per-cpu-dependency.patch removed from -mm tree Message-Id: <20260208081421.ACAAEC4CEF7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency has been removed from the -mm tree. Its filename was watchdog-hardlockup-simplify-perf-event-probe-and-remove-per-cpu-dependency.patch This patch was dropped because it was merged into the mm-nonmm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Qiliang Yuan Subject: watchdog/hardlockup: simplify perf event probe and remove per-cpu dependency Date: Wed, 28 Jan 2026 21:26:14 -0500 Simplify the hardlockup detector's probe path and remove its implicit dependency on pinned per-cpu execution. Refactor hardlockup_detector_event_create() to be stateless. Return the created perf_event pointer to the caller instead of directly modifying the per-cpu 'watchdog_ev' variable. This allows the probe path to safely manage a temporary event without the risk of leaving stale pointers should task migration occur. Link: https://lkml.kernel.org/r/20260129022629.2201331-1-realwujing@gmail.com Signed-off-by: Shouxin Sun Signed-off-by: Junnan Zhang Signed-off-by: Qiliang Yuan Signed-off-by: Qiliang Yuan Reviewed-by: Douglas Anderson Cc: Jinchao Wang Cc: Ingo Molnar Cc: Li Huafei Cc: Song Liu Cc: Thorsten Blum Cc: Wang Jinchao Cc: Yicong Yang Signed-off-by: Andrew Morton --- kernel/watchdog_perf.c | 50 +++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 22 deletions(-) --- a/kernel/watchdog_perf.c~watchdog-hardlockup-simplify-perf-event-probe-and-remove-per-cpu-dependency +++ a/kernel/watchdog_perf.c @@ -118,18 +118,11 @@ static void watchdog_overflow_callback(s watchdog_hardlockup_check(smp_processor_id(), regs); } -static int hardlockup_detector_event_create(void) +static struct perf_event *hardlockup_detector_event_create(unsigned int cpu) { - unsigned int cpu; struct perf_event_attr *wd_attr; struct perf_event *evt; - /* - * Preemption is not disabled because memory will be allocated. - * Ensure CPU-locality by calling this in per-CPU kthread. - */ - WARN_ON(!is_percpu_thread()); - cpu = raw_smp_processor_id(); wd_attr = &wd_hw_attr; wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh); @@ -143,14 +136,7 @@ static int hardlockup_detector_event_cre watchdog_overflow_callback, NULL); } - if (IS_ERR(evt)) { - pr_debug("Perf event create on CPU %d failed with %ld\n", cpu, - PTR_ERR(evt)); - return PTR_ERR(evt); - } - WARN_ONCE(this_cpu_read(watchdog_ev), "unexpected watchdog_ev leak"); - this_cpu_write(watchdog_ev, evt); - return 0; + return evt; } /** @@ -159,17 +145,26 @@ static int hardlockup_detector_event_cre */ void watchdog_hardlockup_enable(unsigned int cpu) { + struct perf_event *evt; + WARN_ON_ONCE(cpu != smp_processor_id()); - if (hardlockup_detector_event_create()) + evt = hardlockup_detector_event_create(cpu); + if (IS_ERR(evt)) { + pr_debug("Perf event create on CPU %d failed with %ld\n", cpu, + PTR_ERR(evt)); return; + } /* use original value for check */ if (!atomic_fetch_inc(&watchdog_cpus)) pr_info("Enabled. Permanently consumes one hw-PMU counter.\n"); + WARN_ONCE(this_cpu_read(watchdog_ev), "unexpected watchdog_ev leak"); + this_cpu_write(watchdog_ev, evt); + watchdog_init_timestamp(); - perf_event_enable(this_cpu_read(watchdog_ev)); + perf_event_enable(evt); } /** @@ -263,19 +258,30 @@ bool __weak __init arch_perf_nmi_is_avai */ int __init watchdog_hardlockup_probe(void) { + struct perf_event *evt; + unsigned int cpu; int ret; if (!arch_perf_nmi_is_available()) return -ENODEV; - ret = hardlockup_detector_event_create(); + if (!hw_nmi_get_sample_period(watchdog_thresh)) + return -EINVAL; - if (ret) { + /* + * Test hardware PMU availability by creating a temporary perf event. + * The event is released immediately. + */ + cpu = raw_smp_processor_id(); + evt = hardlockup_detector_event_create(cpu); + if (IS_ERR(evt)) { pr_info("Perf NMI watchdog permanently disabled\n"); + ret = PTR_ERR(evt); } else { - perf_event_release_kernel(this_cpu_read(watchdog_ev)); - this_cpu_write(watchdog_ev, NULL); + perf_event_release_kernel(evt); + ret = 0; } + return ret; } _ Patches currently in -mm which might be from realwujing@gmail.com are