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> Subject: [PATCH v9 03/12] kthread/smpboot: Do not park in kthread_create_on_cpu() Date: Thu, 16 Jun 2016 13:17:22 +0200 [thread overview] Message-ID: <1466075851-24013-4-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1466075851-24013-1-git-send-email-pmladek@suse.com> kthread_create_on_cpu() was added by the commit 2a1d446019f9a5983e ("kthread: Implement park/unpark facility"). It is currently used only when enabling new CPU. For this purpose, the newly created kthread has to be parked. The CPU binding is a bit tricky. The kthread is parked when the CPU has not been allowed yet. And the CPU is bound when the kthread is unparked. The function would be useful for more per-CPU kthreads, e.g. bnx2fc_thread, fcoethread. For this purpose, the newly created kthread should stay in the uninterruptible state. This patch moves the parking into smpboot. It binds the thread already when created. Then the function might be used universally. Also the behavior is consistent with kthread_create() and kthread_create_on_node(). Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/kthread.c | 8 ++++++-- kernel/smpboot.c | 5 +++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 16cea43c3c2c..aea12c9fec98 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -390,10 +390,10 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), cpu); if (IS_ERR(p)) return p; + kthread_bind(p, cpu); + /* CPU hotplug need to bind once again when unparking the thread. */ set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); to_kthread(p)->cpu = cpu; - /* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */ - kthread_park(p); return p; } @@ -407,6 +407,10 @@ static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) * which might be about to be cleared. */ if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { + /* + * Newly created kthread was parked when the CPU was offline. + * The binding was lost and we need to set it again. + */ if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) __kthread_bind(k, kthread->cpu, TASK_PARKED); wake_up_state(k, TASK_PARKED); diff --git a/kernel/smpboot.c b/kernel/smpboot.c index 13bc43d1fb22..4a5c6e73ecd4 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -186,6 +186,11 @@ __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu) kfree(td); return PTR_ERR(tsk); } + /* + * Park the thread so that it could start right on the CPU + * when it is available. + */ + kthread_park(tsk); get_task_struct(tsk); *per_cpu_ptr(ht->store, cpu) = tsk; if (ht->create) { -- 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> Subject: [PATCH v9 03/12] kthread/smpboot: Do not park in kthread_create_on_cpu() Date: Thu, 16 Jun 2016 13:17:22 +0200 [thread overview] Message-ID: <1466075851-24013-4-git-send-email-pmladek@suse.com> (raw) In-Reply-To: <1466075851-24013-1-git-send-email-pmladek@suse.com> kthread_create_on_cpu() was added by the commit 2a1d446019f9a5983e ("kthread: Implement park/unpark facility"). It is currently used only when enabling new CPU. For this purpose, the newly created kthread has to be parked. The CPU binding is a bit tricky. The kthread is parked when the CPU has not been allowed yet. And the CPU is bound when the kthread is unparked. The function would be useful for more per-CPU kthreads, e.g. bnx2fc_thread, fcoethread. For this purpose, the newly created kthread should stay in the uninterruptible state. This patch moves the parking into smpboot. It binds the thread already when created. Then the function might be used universally. Also the behavior is consistent with kthread_create() and kthread_create_on_node(). Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> --- kernel/kthread.c | 8 ++++++-- kernel/smpboot.c | 5 +++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index 16cea43c3c2c..aea12c9fec98 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -390,10 +390,10 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), cpu); if (IS_ERR(p)) return p; + kthread_bind(p, cpu); + /* CPU hotplug need to bind once again when unparking the thread. */ set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags); to_kthread(p)->cpu = cpu; - /* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */ - kthread_park(p); return p; } @@ -407,6 +407,10 @@ static void __kthread_unpark(struct task_struct *k, struct kthread *kthread) * which might be about to be cleared. */ if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) { + /* + * Newly created kthread was parked when the CPU was offline. + * The binding was lost and we need to set it again. + */ if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) __kthread_bind(k, kthread->cpu, TASK_PARKED); wake_up_state(k, TASK_PARKED); diff --git a/kernel/smpboot.c b/kernel/smpboot.c index 13bc43d1fb22..4a5c6e73ecd4 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -186,6 +186,11 @@ __smpboot_create_thread(struct smp_hotplug_thread *ht, unsigned int cpu) kfree(td); return PTR_ERR(tsk); } + /* + * Park the thread so that it could start right on the CPU + * when it is available. + */ + kthread_park(tsk); get_task_struct(tsk); *per_cpu_ptr(ht->store, cpu) = tsk; if (ht->create) { -- 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:[~2016-06-16 11:18 UTC|newest] Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-06-16 11:17 [PATCH v9 00/12] kthread: Kthread worker API improvements Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-16 11:17 ` [PATCH v9 01/12] kthread: Rename probe_kthread_data() to kthread_probe_data() Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:16 ` Tejun Heo 2016-06-20 19:16 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 02/12] kthread: Kthread worker API cleanup Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:27 ` Tejun Heo 2016-06-20 19:27 ` Tejun Heo 2016-06-16 11:17 ` Petr Mladek [this message] 2016-06-16 11:17 ` [PATCH v9 03/12] kthread/smpboot: Do not park in kthread_create_on_cpu() Petr Mladek 2016-06-16 11:17 ` [PATCH v9 04/12] kthread: Allow to call __kthread_create_on_node() with va_list args Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:51 ` Tejun Heo 2016-06-20 19:51 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 05/12] kthread: Add kthread_create_worker*() Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:55 ` Tejun Heo 2016-06-20 19:55 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 06/12] kthread: Add kthread_drain_worker() Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:56 ` Tejun Heo 2016-06-20 19:56 ` Tejun Heo 2016-06-22 20:54 ` Peter Zijlstra 2016-06-22 20:54 ` Peter Zijlstra 2016-06-23 21:32 ` Tejun Heo 2016-06-23 21:32 ` Tejun Heo 2016-06-23 21:32 ` Tejun Heo 2016-06-24 7:05 ` Peter Zijlstra 2016-06-24 7:05 ` Peter Zijlstra 2016-06-24 9:08 ` Petr Mladek 2016-06-24 9:08 ` Petr Mladek 2016-06-24 15:54 ` Tejun Heo 2016-06-24 15:54 ` Tejun Heo 2016-06-27 14:33 ` Petr Mladek 2016-06-27 14:33 ` Petr Mladek 2016-06-27 14:33 ` Petr Mladek 2016-06-28 17:04 ` Tejun Heo 2016-06-28 17:04 ` Tejun Heo 2016-06-29 8:17 ` Petr Mladek 2016-06-29 8:17 ` Petr Mladek 2016-06-29 13:15 ` Tejun Heo 2016-06-29 13:15 ` Tejun Heo 2016-06-29 13:15 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 07/12] kthread: Add kthread_destroy_worker() Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 19:57 ` Tejun Heo 2016-06-20 19:57 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 08/12] kthread: Detect when a kthread work is used by more workers Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 20:10 ` Tejun Heo 2016-06-20 20:10 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 09/12] kthread: Initial support for delayed kthread work Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 20:20 ` Tejun Heo 2016-06-20 20:20 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 10/12] kthread: Allow to cancel " Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 20:27 ` Tejun Heo 2016-06-20 20:27 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 11/12] kthread: Allow to modify delayed " Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 20:29 ` Tejun Heo 2016-06-20 20:29 ` Tejun Heo 2016-06-16 11:17 ` [PATCH v9 12/12] kthread: Better support freezable kthread workers Petr Mladek 2016-06-16 11:17 ` Petr Mladek 2016-06-20 20:30 ` Tejun Heo 2016-06-20 20:30 ` Tejun Heo
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