diff options
author | Thomas Gleixner <tglx@linutronix.de> | 2011-06-06 12:20:33 +0200 |
---|---|---|
committer | Clark Williams <williams@redhat.com> | 2012-02-15 10:32:47 -0600 |
commit | 2ee05a75c070ce8c1b5577eb8909c762966d278f (patch) | |
tree | 1564e53b9429edb88410cb0d7ddd2e0db0f6c0ba | |
parent | a2feba07d064c8ea60e0b8904801526c048a0c7c (diff) |
sched-mmdrop-delayed.patch
Needs thread context (pgd_lock) -> ifdeffed. workqueues wont work with
RT
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r-- | include/linux/mm_types.h | 4 | ||||
-rw-r--r-- | include/linux/sched.h | 12 | ||||
-rw-r--r-- | kernel/fork.c | 15 | ||||
-rw-r--r-- | kernel/sched.c | 21 |
4 files changed, 49 insertions, 3 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 1ec126f23eaa..c303a27981fe 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -12,6 +12,7 @@ #include <linux/completion.h> #include <linux/cpumask.h> #include <linux/page-debug-flags.h> +#include <linux/rcupdate.h> #include <asm/page.h> #include <asm/mmu.h> @@ -393,6 +394,9 @@ struct mm_struct { #ifdef CONFIG_CPUMASK_OFFSTACK struct cpumask cpumask_allocation; #endif +#ifdef CONFIG_PREEMPT_RT_BASE + struct rcu_head delayed_drop; +#endif }; static inline void mm_init_cpumask(struct mm_struct *mm) diff --git a/include/linux/sched.h b/include/linux/sched.h index fb5e51fc5af6..e6f37cacf751 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2268,12 +2268,24 @@ extern struct mm_struct * mm_alloc(void); /* mmdrop drops the mm and the page tables */ extern void __mmdrop(struct mm_struct *); + static inline void mmdrop(struct mm_struct * mm) { if (unlikely(atomic_dec_and_test(&mm->mm_count))) __mmdrop(mm); } +#ifdef CONFIG_PREEMPT_RT_BASE +extern void __mmdrop_delayed(struct rcu_head *rhp); +static inline void mmdrop_delayed(struct mm_struct *mm) +{ + if (atomic_dec_and_test(&mm->mm_count)) + call_rcu(&mm->delayed_drop, __mmdrop_delayed); +} +#else +# define mmdrop_delayed(mm) mmdrop(mm) +#endif + /* mmput gets rid of the mappings and all user-space */ extern void mmput(struct mm_struct *); /* Grab a reference to a task's mm, if it is not already going away */ diff --git a/kernel/fork.c b/kernel/fork.c index 6679093b31e2..56188b0c9d21 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -201,7 +201,7 @@ EXPORT_SYMBOL_GPL(__put_task_struct); #else void __put_task_struct_cb(struct rcu_head *rhp) { - struct task_struct *tsk = container_of(rhp, struct task_struct, rcu); + struct task_struct *tsk = container_of(rhp, struct task_struct, put_rcu); __put_task_struct(tsk); @@ -552,6 +552,19 @@ void __mmdrop(struct mm_struct *mm) } EXPORT_SYMBOL_GPL(__mmdrop); +#ifdef CONFIG_PREEMPT_RT_BASE +/* + * RCU callback for delayed mm drop. Not strictly rcu, but we don't + * want another facility to make this work. + */ +void __mmdrop_delayed(struct rcu_head *rhp) +{ + struct mm_struct *mm = container_of(rhp, struct mm_struct, delayed_drop); + + __mmdrop(mm); +} +#endif + /* * Decrement the use count and release all resources for an mm. */ diff --git a/kernel/sched.c b/kernel/sched.c index 6e2bf9e29ca5..3ff2d0f1fcfe 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3174,8 +3174,12 @@ static void finish_task_switch(struct rq *rq, struct task_struct *prev) finish_lock_switch(rq, prev); fire_sched_in_preempt_notifiers(current); + /* + * We use mmdrop_delayed() here so we don't have to do the + * full __mmdrop() when we are the last user. + */ if (mm) - mmdrop(mm); + mmdrop_delayed(mm); if (unlikely(prev_state == TASK_DEAD)) { /* * Remove function-return probe instances associated with this @@ -6303,6 +6307,8 @@ static int migration_cpu_stop(void *data) #ifdef CONFIG_HOTPLUG_CPU +static DEFINE_PER_CPU(struct mm_struct *, idle_last_mm); + /* * Ensures that the idle task is using init_mm right before its cpu goes * offline. @@ -6315,7 +6321,12 @@ void idle_task_exit(void) if (mm != &init_mm) switch_mm(mm, &init_mm, current); - mmdrop(mm); + + /* + * Defer the cleanup to an alive cpu. On RT we can neither + * call mmdrop() nor mmdrop_delayed() from here. + */ + per_cpu(idle_last_mm, smp_processor_id()) = mm; } /* @@ -6660,6 +6671,12 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) migrate_nr_uninterruptible(rq); calc_global_load_remove(rq); break; + case CPU_DEAD: + if (per_cpu(idle_last_mm, cpu)) { + mmdrop(per_cpu(idle_last_mm, cpu)); + per_cpu(idle_last_mm, cpu) = NULL; + } + break; #endif } |