From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: [merged] kthread-smpboot-do-not-park-in-kthread_create_on_cpu.patch removed from -mm tree Date: Wed, 12 Oct 2016 12:26:06 -0700 Message-ID: <57fe8e4e.DFh0Pgj1JwrPAGEO%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33524 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755899AbcJLT0H (ORCPT ); Wed, 12 Oct 2016 15:26:07 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: pmladek@suse.com, bp@suse.de, jkosina@suse.cz, josh@joshtriplett.org, mhocko@suse.cz, mingo@redhat.com, oleg@redhat.com, paulmck@linux.vnet.ibm.com, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, tj@kernel.org, vbabka@suse.cz, mm-commits@vger.kernel.org The patch titled Subject: kthread/smpboot: do not park in kthread_create_on_cpu() has been removed from the -mm tree. Its filename was kthread-smpboot-do-not-park-in-kthread_create_on_cpu.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Petr Mladek Subject: kthread/smpboot: do not park in kthread_create_on_cpu() 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(). Link: http://lkml.kernel.org/r/1470754545-17632-4-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek Reviewed-by: Thomas Gleixner Cc: Oleg Nesterov Cc: Tejun Heo Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Steven Rostedt Cc: "Paul E. McKenney" Cc: Josh Triplett Cc: Jiri Kosina Cc: Borislav Petkov Cc: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- kernel/kthread.c | 8 ++++++-- kernel/smpboot.c | 5 +++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff -puN kernel/kthread.c~kthread-smpboot-do-not-park-in-kthread_create_on_cpu kernel/kthread.c --- a/kernel/kthread.c~kthread-smpboot-do-not-park-in-kthread_create_on_cpu +++ a/kernel/kthread.c @@ -390,10 +390,10 @@ struct task_struct *kthread_create_on_cp 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 * 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 -puN kernel/smpboot.c~kthread-smpboot-do-not-park-in-kthread_create_on_cpu kernel/smpboot.c --- a/kernel/smpboot.c~kthread-smpboot-do-not-park-in-kthread_create_on_cpu +++ a/kernel/smpboot.c @@ -186,6 +186,11 @@ __smpboot_create_thread(struct smp_hotpl 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) { _ Patches currently in -mm which might be from pmladek@suse.com are