From: Petr Mladek <pmladek@suse.com> To: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>, Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Josh Triplett <josh@joshtriplett.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>, Michal Hocko <mhocko@suse.cz>, linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>, linux-watchdog@vger.kernel.org Subject: [PATCH v4 15/22] hung_task: Convert hungtaskd into kthread worker API Date: Mon, 25 Jan 2016 16:45:04 +0100 [thread overview] Message-ID: <1453736711-6703-16-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1453736711-6703-1-git-send-email-pmladek@suse.com> Kthreads are currently implemented as an infinite loop. Each has its own variant of checks for terminating, freezing, awakening. In many cases it is unclear to say in which state it is and sometimes it is done a wrong way. The plan is to convert kthreads into kthread_worker or workqueues API. It allows to split the functionality into separate operations. It helps to make a better structure. Also it defines a clean state where no locks are taken, IRQs blocked, the kthread might sleep or even be safely migrated. The kthread worker API is useful when we want to have a dedicated single thread for the work. It helps to make sure that it is available when needed. Also it allows a better control, e.g. define a scheduling priority. This patch converts hungtaskd() in kthread worker API because it modifies the priority. The conversion is pretty straightforward. One iteration of the main cycle is transferred into a self-queuing delayed kthread work. We do not longer need to check if it was waken earlier. Instead, the work timeout is modified when the timeout value is changed. The user nice value is set from hung_task_init(). Otherwise, we would need to add an extra init_work. The patch also handles the error when the kthead worker could not be crated from some reasons. It was broken before. For example, wake_up_process would have failed if watchdog_task inclueded an error code instead of a valid pointer. Signed-off-by: Petr Mladek <pmladek@suse.com> CC: linux-watchdog@vger.kernel.org --- kernel/hung_task.c | 41 +++++++++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 16 deletions(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index e0f90c2b57aa..65026f8b750e 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -41,7 +41,9 @@ int __read_mostly sysctl_hung_task_warnings = 10; static int __read_mostly did_panic; -static struct task_struct *watchdog_task; +static struct kthread_worker *watchdog_worker; +static void watchdog_func(struct kthread_work *dummy); +static DEFINE_DELAYED_KTHREAD_WORK(watchdog_work, watchdog_func); /* * Should we panic (and reboot, if panic_timeout= is set) when a @@ -205,7 +207,9 @@ int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, if (ret || !write) goto out; - wake_up_process(watchdog_task); + if (watchdog_worker) + mod_delayed_kthread_work(watchdog_worker, &watchdog_work, + timeout_jiffies(sysctl_hung_task_timeout_secs)); out: return ret; @@ -222,30 +226,35 @@ EXPORT_SYMBOL_GPL(reset_hung_task_detector); /* * kthread which checks for tasks stuck in D state */ -static int watchdog(void *dummy) +static void watchdog_func(struct kthread_work *dummy) { - set_user_nice(current, 0); + unsigned long timeout = sysctl_hung_task_timeout_secs; - for ( ; ; ) { - unsigned long timeout = sysctl_hung_task_timeout_secs; + if (atomic_xchg(&reset_hung_task, 0)) + goto next; - while (schedule_timeout_interruptible(timeout_jiffies(timeout))) - timeout = sysctl_hung_task_timeout_secs; + check_hung_uninterruptible_tasks(timeout); - if (atomic_xchg(&reset_hung_task, 0)) - continue; - - check_hung_uninterruptible_tasks(timeout); - } - - return 0; +next: + queue_delayed_kthread_work(watchdog_worker, &watchdog_work, + timeout_jiffies(timeout)); } static int __init hung_task_init(void) { + struct kthread_worker *worker; + atomic_notifier_chain_register(&panic_notifier_list, &panic_block); - watchdog_task = kthread_run(watchdog, NULL, "khungtaskd"); + worker = create_kthread_worker(0, "khungtaskd"); + if (IS_ERR(worker)) { + pr_warn("Failed to create khungtaskd\n"); + goto out; + } + watchdog_worker = worker; + set_user_nice(worker->task, 0); + queue_delayed_kthread_work(worker, &watchdog_work, 0); +out: return 0; } subsys_initcall(hung_task_init); -- 1.8.5.6
WARNING: multiple messages have this Message-ID (diff)
From: Petr Mladek <pmladek@suse.com> To: Andrew Morton <akpm@linux-foundation.org>, Oleg Nesterov <oleg@redhat.com>, Tejun Heo <tj@kernel.org>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Josh Triplett <josh@joshtriplett.org>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Jiri Kosina <jkosina@suse.cz>, Borislav Petkov <bp@suse.de>, Michal Hocko <mhocko@suse.cz>, linux-mm@kvack.org, Vlastimil Babka <vbabka@suse.cz>, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Petr Mladek <pmladek@suse.com>, linux-watchdog@vger.kernel.org Subject: [PATCH v4 15/22] hung_task: Convert hungtaskd into kthread worker API Date: Mon, 25 Jan 2016 16:45:04 +0100 [thread overview] Message-ID: <1453736711-6703-16-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1453736711-6703-1-git-send-email-pmladek@suse.com> Kthreads are currently implemented as an infinite loop. Each has its own variant of checks for terminating, freezing, awakening. In many cases it is unclear to say in which state it is and sometimes it is done a wrong way. The plan is to convert kthreads into kthread_worker or workqueues API. It allows to split the functionality into separate operations. It helps to make a better structure. Also it defines a clean state where no locks are taken, IRQs blocked, the kthread might sleep or even be safely migrated. The kthread worker API is useful when we want to have a dedicated single thread for the work. It helps to make sure that it is available when needed. Also it allows a better control, e.g. define a scheduling priority. This patch converts hungtaskd() in kthread worker API because it modifies the priority. The conversion is pretty straightforward. One iteration of the main cycle is transferred into a self-queuing delayed kthread work. We do not longer need to check if it was waken earlier. Instead, the work timeout is modified when the timeout value is changed. The user nice value is set from hung_task_init(). Otherwise, we would need to add an extra init_work. The patch also handles the error when the kthead worker could not be crated from some reasons. It was broken before. For example, wake_up_process would have failed if watchdog_task inclueded an error code instead of a valid pointer. Signed-off-by: Petr Mladek <pmladek@suse.com> CC: linux-watchdog@vger.kernel.org --- kernel/hung_task.c | 41 +++++++++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 16 deletions(-) diff --git a/kernel/hung_task.c b/kernel/hung_task.c index e0f90c2b57aa..65026f8b750e 100644 --- a/kernel/hung_task.c +++ b/kernel/hung_task.c @@ -41,7 +41,9 @@ int __read_mostly sysctl_hung_task_warnings = 10; static int __read_mostly did_panic; -static struct task_struct *watchdog_task; +static struct kthread_worker *watchdog_worker; +static void watchdog_func(struct kthread_work *dummy); +static DEFINE_DELAYED_KTHREAD_WORK(watchdog_work, watchdog_func); /* * Should we panic (and reboot, if panic_timeout= is set) when a @@ -205,7 +207,9 @@ int proc_dohung_task_timeout_secs(struct ctl_table *table, int write, if (ret || !write) goto out; - wake_up_process(watchdog_task); + if (watchdog_worker) + mod_delayed_kthread_work(watchdog_worker, &watchdog_work, + timeout_jiffies(sysctl_hung_task_timeout_secs)); out: return ret; @@ -222,30 +226,35 @@ EXPORT_SYMBOL_GPL(reset_hung_task_detector); /* * kthread which checks for tasks stuck in D state */ -static int watchdog(void *dummy) +static void watchdog_func(struct kthread_work *dummy) { - set_user_nice(current, 0); + unsigned long timeout = sysctl_hung_task_timeout_secs; - for ( ; ; ) { - unsigned long timeout = sysctl_hung_task_timeout_secs; + if (atomic_xchg(&reset_hung_task, 0)) + goto next; - while (schedule_timeout_interruptible(timeout_jiffies(timeout))) - timeout = sysctl_hung_task_timeout_secs; + check_hung_uninterruptible_tasks(timeout); - if (atomic_xchg(&reset_hung_task, 0)) - continue; - - check_hung_uninterruptible_tasks(timeout); - } - - return 0; +next: + queue_delayed_kthread_work(watchdog_worker, &watchdog_work, + timeout_jiffies(timeout)); } static int __init hung_task_init(void) { + struct kthread_worker *worker; + atomic_notifier_chain_register(&panic_notifier_list, &panic_block); - watchdog_task = kthread_run(watchdog, NULL, "khungtaskd"); + worker = create_kthread_worker(0, "khungtaskd"); + if (IS_ERR(worker)) { + pr_warn("Failed to create khungtaskd\n"); + goto out; + } + watchdog_worker = worker; + set_user_nice(worker->task, 0); + queue_delayed_kthread_work(worker, &watchdog_work, 0); +out: return 0; } subsys_initcall(hung_task_init); -- 1.8.5.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-01-25 15:52 UTC|newest] Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-01-25 15:44 [PATCH v4 00/22] kthread: Use kthread worker API more widely Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 01/22] timer: Allow to check when the timer callback has not finished yet Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 18:44 ` Tejun Heo 2016-01-25 18:44 ` Tejun Heo 2016-01-25 15:44 ` [PATCH v4 02/22] kthread/smpboot: Do not park in kthread_create_on_cpu() Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 03/22] kthread: Allow to call __kthread_create_on_node() with va_list args Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 04/22] kthread: Add create_kthread_worker*() Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 18:53 ` Tejun Heo 2016-01-25 18:53 ` Tejun Heo 2016-02-16 15:44 ` Petr Mladek 2016-02-16 15:44 ` Petr Mladek 2016-02-16 16:08 ` Tejun Heo 2016-02-16 16:08 ` Tejun Heo 2016-02-16 16:08 ` Tejun Heo 2016-02-16 16:10 ` Petr Mladek 2016-02-16 16:10 ` Petr Mladek 2016-02-16 16:10 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 05/22] kthread: Add drain_kthread_worker() Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 06/22] kthread: Add destroy_kthread_worker() Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 07/22] kthread: Detect when a kthread work is used by more workers Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 18:57 ` Tejun Heo 2016-01-25 18:57 ` Tejun Heo 2016-01-25 18:57 ` Tejun Heo 2016-02-16 16:38 ` Petr Mladek 2016-02-16 16:38 ` Petr Mladek 2016-02-16 16:38 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 08/22] kthread: Initial support for delayed kthread work Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 19:04 ` Tejun Heo 2016-01-25 19:04 ` Tejun Heo 2016-01-25 19:04 ` Tejun Heo 2016-01-25 15:44 ` [PATCH v4 09/22] kthread: Allow to cancel " Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 19:17 ` Tejun Heo 2016-01-25 19:17 ` Tejun Heo 2016-02-19 16:22 ` Petr Mladek 2016-02-19 16:22 ` Petr Mladek 2016-01-25 15:44 ` [PATCH v4 10/22] kthread: Allow to modify delayed " Petr Mladek 2016-01-25 15:44 ` Petr Mladek 2016-01-25 19:19 ` Tejun Heo 2016-01-25 19:19 ` Tejun Heo 2016-01-25 15:45 ` [PATCH v4 11/22] kthread: Better support freezable kthread workers Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 19:21 ` Tejun Heo 2016-01-25 19:21 ` Tejun Heo 2016-01-25 15:45 ` [PATCH v4 12/22] kthread: Use try_lock_kthread_work() in flush_kthread_work() Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 13/22] mm/huge_page: Convert khugepaged() into kthread worker API Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 14/22] ring_buffer: Convert benchmark kthreads " Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` Petr Mladek [this message] 2016-01-25 15:45 ` [PATCH v4 15/22] hung_task: Convert hungtaskd " Petr Mladek 2016-01-25 15:45 ` [PATCH v4 16/22] kmemleak: Convert kmemleak kthread " Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 17/22] ipmi: Convert kipmi " Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 18/22] IB/fmr_pool: Convert the cleanup thread " Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 19/22] memstick/r592: Better synchronize debug messages in r592_io kthread Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 20/22] memstick/r592: convert r592_io kthread into kthread worker API Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 15:45 ` [PATCH v4 21/22] thermal/intel_powerclamp: Remove duplicated code that starts the kthread Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 16:23 ` Jacob Pan 2016-01-25 16:23 ` Jacob Pan 2016-01-25 15:45 ` [PATCH v4 22/22] thermal/intel_powerclamp: Convert the kthread to kthread worker API Petr Mladek 2016-01-25 15:45 ` Petr Mladek 2016-01-25 16:28 ` Jacob Pan 2016-01-25 16:28 ` Jacob Pan
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