From 25834c73f93af7f0712c98ca4593691592e6b360 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 15 May 2015 17:43:34 +0200 Subject: sched: Fix a race between __kthread_bind() and sched_setaffinity() Because sched_setscheduler() checks p->flags & PF_NO_SETAFFINITY without locks, a caller might observe an old value and race with the set_cpus_allowed_ptr() call from __kthread_bind() and effectively undo it: __kthread_bind() do_set_cpus_allowed() sched_setaffinity() if (p->flags & PF_NO_SETAFFINITIY) set_cpus_allowed_ptr() p->flags |= PF_NO_SETAFFINITY Fix the bug by putting everything under the regular scheduler locks. This also closes a hole in the serialization of task_struct::{nr_,}cpus_allowed. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Mike Galbraith Cc: Oleg Nesterov Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dedekind1@gmail.com Cc: juri.lelli@arm.com Cc: mgorman@suse.de Cc: riel@redhat.com Cc: rostedt@goodmis.org Link: http://lkml.kernel.org/r/20150515154833.545640346@infradead.org Signed-off-by: Ingo Molnar --- include/linux/kthread.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kthread.h') diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 13d55206ccf6..869b21dcf503 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -38,6 +38,7 @@ struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), }) void kthread_bind(struct task_struct *k, unsigned int cpu); +void kthread_bind_mask(struct task_struct *k, const struct cpumask *mask); int kthread_stop(struct task_struct *k); bool kthread_should_stop(void); bool kthread_should_park(void); -- cgit v1.2.3 From e9f069868d60550c4b46f084ac9276a57c1b4711 Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Fri, 4 Sep 2015 15:42:42 -0700 Subject: kernel/kthread.c:kthread_create_on_node(): clarify documentation - Make it clear that the `node' arg refers to memory allocations only: kthread_create_on_node() does not pin the new thread to that node's CPUs. - Encourage the use of NUMA_NO_NODE. [nzimmer@sgi.com: use NUMA_NO_NODE in kthread_create() also] Cc: Nathan Zimmer Cc: Tejun Heo Cc: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kthread.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/kthread.h') diff --git a/include/linux/kthread.h b/include/linux/kthread.h index 869b21dcf503..e691b6a23f72 100644 --- a/include/linux/kthread.h +++ b/include/linux/kthread.h @@ -11,7 +11,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), const char namefmt[], ...); #define kthread_create(threadfn, data, namefmt, arg...) \ - kthread_create_on_node(threadfn, data, -1, namefmt, ##arg) + kthread_create_on_node(threadfn, data, NUMA_NO_NODE, namefmt, ##arg) struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data), -- cgit v1.2.3