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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-13 21:22:32 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-09-13 21:22:32 +0200 |
commit | ec846ecd6350857a8b8b9a6b78c763d45e0f09b8 (patch) | |
tree | 44896da8501c42f2c41b7fc17975dc7fe16b2789 | |
parent | Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/ker... (diff) | |
parent | sched/debug: Add debugfs knob for "sched_debug" (diff) | |
download | linux-ec846ecd6350857a8b8b9a6b78c763d45e0f09b8.tar.xz linux-ec846ecd6350857a8b8b9a6b78c763d45e0f09b8.zip |
Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
"Three CPU hotplug related fixes and a debugging improvement"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Add debugfs knob for "sched_debug"
sched/core: WARN() when migrating to an offline CPU
sched/fair: Plug hole between hotplug and active_load_balance()
sched/fair: Avoid newidle balance for !active CPUs
-rw-r--r-- | kernel/sched/core.c | 4 | ||||
-rw-r--r-- | kernel/sched/debug.c | 5 | ||||
-rw-r--r-- | kernel/sched/fair.c | 13 | ||||
-rw-r--r-- | kernel/sched/sched.h | 2 | ||||
-rw-r--r-- | kernel/sched/topology.c | 4 |
5 files changed, 25 insertions, 3 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 136a76d80dbf..18a6966567da 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1173,6 +1173,10 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) || lockdep_is_held(&task_rq(p)->lock))); #endif + /* + * Clearly, migrating tasks to offline CPUs is a fairly daft thing. + */ + WARN_ON_ONCE(!cpu_online(new_cpu)); #endif trace_sched_migrate_task(p, new_cpu); diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 8e536d963652..01217fb5a5de 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -181,11 +181,16 @@ static const struct file_operations sched_feat_fops = { .release = single_release, }; +__read_mostly bool sched_debug_enabled; + static __init int sched_init_debug(void) { debugfs_create_file("sched_features", 0644, NULL, NULL, &sched_feat_fops); + debugfs_create_bool("sched_debug", 0644, NULL, + &sched_debug_enabled); + return 0; } late_initcall(sched_init_debug); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0a85641e62ce..70ba32e08a23 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8437,6 +8437,12 @@ static int idle_balance(struct rq *this_rq, struct rq_flags *rf) this_rq->idle_stamp = rq_clock(this_rq); /* + * Do not pull tasks towards !active CPUs... + */ + if (!cpu_active(this_cpu)) + return 0; + + /* * This is OK, because current is on_cpu, which avoids it being picked * for load-balance and preemption/IRQs are still disabled avoiding * further scheduler activity on it and we're being very careful to @@ -8543,6 +8549,13 @@ static int active_load_balance_cpu_stop(void *data) struct rq_flags rf; rq_lock_irq(busiest_rq, &rf); + /* + * Between queueing the stop-work and running it is a hole in which + * CPUs can become inactive. We should not move tasks from or to + * inactive CPUs. + */ + if (!cpu_active(busiest_cpu) || !cpu_active(target_cpu)) + goto out_unlock; /* make sure the requested cpu hasn't gone down in the meantime */ if (unlikely(busiest_cpu != smp_processor_id() || diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 746ac78ff492..14db76cd496f 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1951,6 +1951,8 @@ extern struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq); extern struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq); #ifdef CONFIG_SCHED_DEBUG +extern bool sched_debug_enabled; + extern void print_cfs_stats(struct seq_file *m, int cpu); extern void print_rt_stats(struct seq_file *m, int cpu); extern void print_dl_stats(struct seq_file *m, int cpu); diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 5d0062cc10cb..f1cf4f306a82 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -14,11 +14,9 @@ cpumask_var_t sched_domains_tmpmask2; #ifdef CONFIG_SCHED_DEBUG -static __read_mostly int sched_debug_enabled; - static int __init sched_debug_setup(char *str) { - sched_debug_enabled = 1; + sched_debug_enabled = true; return 0; } |