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Thu, 05 Feb 2026 23:06:04 -0800 (PST) From: Qiliang Yuan Date: Fri, 06 Feb 2026 02:04:27 -0500 Subject: [PATCH RFC 06/12] watchdog: Allow runtime toggle of hardlockup detector on CPUs MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260206-feature-dynamic_isolcpus_dhei-v1-6-00a711eb0c74@gmail.com> References: <20260206-feature-dynamic_isolcpus_dhei-v1-0-00a711eb0c74@gmail.com> In-Reply-To: <20260206-feature-dynamic_isolcpus_dhei-v1-0-00a711eb0c74@gmail.com> To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , Thomas Gleixner , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Uladzislau Rezki , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Tejun Heo , Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Anna-Maria Behnsen , Ingo Molnar Cc: linux-kernel@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org, Qiliang Yuan , Qiliang Yuan X-Mailer: b4 0.14.3 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: EC0FE14000F X-Stat-Signature: siuui8n4n5n8nbn3xons5t3iiszcxj9r X-HE-Tag: 1770361565-773842 X-HE-Meta: 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 Gu8VPPZp dcsLGnezp6fRlfPbEN0YEjHZzDDS+A4EBv7lhf7RU7bKpDBDtpCf9toqljUp3bhxIpVtW5zXvez3wzWIKo4vfEfbbM+lOQ7lh6gYypkFpHOls0iu4Lfe+NmfQT7V3rbAkXvmyD/yqFW9hLkMnK9fn3y8ml3OGFHFzXlD8q1GDrSWMEiizwv1aCQ2/Ohp8hhEDic+Dpr8mXeBqBPlxqnTEOC2nfgdp63c5zRJhT7ayc7//wjelNFFtbjV/q7ZOda9rxPBEl6oQ1dg4/dNyBdsEEbIaB6mcJCE3a2F6z5Wt0KpWXCgVl0nAMMCc98y8ptxKT+z5b6WUyQN5eWQix1H+5Z9w7FIbT6rTauXZfAZJr5caSkwiRWxsi+kctcZ0vt5TM7aU+wn7C7tmNpmGAzUtKWrjNNAPeWeU2/1sMev5Zw5dv7B1SzEAZYX6rqXV6sDjBImL90ugbfmLWIHP6AAXd02k1xaaVUpecwymnQ8GwmXxuP95s4XGNo4q7KnV6QeAU5NIw/w/yS5kvmHZLlVIhNtzeISNf0LPVGnVYgBORefzDzU9EhbhAUV+1w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: The lockup detector (watchdog) affinity is initially set based on the HK_TYPE_TIMER housekeeping mask. However, if this mask is updated at runtime, the watchdog threads remain on their original CPUs. Register a housekeeping notifier to update watchdog_cpumask and trigger a reconfiguration via proc_watchdog_update() when the HK_TYPE_TIMER housekeeping mask changes. This ensures that watchdog threads are synchronized with the new isolation boundaries. Signed-off-by: Qiliang Yuan Signed-off-by: Qiliang Yuan --- kernel/watchdog.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 366122f4a0f8..2922d7f93d61 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -1359,6 +1360,28 @@ static int __init lockup_detector_check(void) } late_initcall_sync(lockup_detector_check); +static int watchdog_housekeeping_reconfigure(struct notifier_block *nb, + unsigned long action, void *data) +{ + if (action == HK_UPDATE_MASK) { + unsigned int type = (unsigned long)data; + + if (type == HK_TYPE_TIMER) { + mutex_lock(&watchdog_mutex); + cpumask_copy(&watchdog_cpumask, + housekeeping_cpumask(HK_TYPE_TIMER)); + proc_watchdog_update(false); + mutex_unlock(&watchdog_mutex); + } + } + + return NOTIFY_OK; +} + +static struct notifier_block watchdog_housekeeping_nb = { + .notifier_call = watchdog_housekeeping_reconfigure, +}; + void __init lockup_detector_init(void) { if (tick_nohz_full_enabled()) @@ -1373,4 +1396,5 @@ void __init lockup_detector_init(void) allow_lockup_detector_init_retry = true; lockup_detector_setup(); + housekeeping_register_notifier(&watchdog_housekeeping_nb); } -- 2.51.0