* [PATCH 0/3] sched: fix tg_has_rt_tasks(), tasklist_lock cleanups
@ 2014-09-21 19:33 Oleg Nesterov
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Oleg Nesterov @ 2014-09-21 19:33 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra; +Cc: Kirill Tkhai, Mike Galbraith, linux-kernel
This textually depends on
5d07f4202c5d63b73ba1734ed38e08461a689313
"sched: s/do_each_thread/for_each_process_thread/ in core.c"
d38e83c715270cc2e137bbf6f25206c8c023896b
"sched: s/do_each_thread/for_each_process_thread/ in debug.c"
in -tip tree.
Kirill, you seem to agree with 1/3, I'll appreciate your ack.
Oleg.
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks()
2014-09-21 19:33 [PATCH 0/3] sched: fix tg_has_rt_tasks(), tasklist_lock cleanups Oleg Nesterov
@ 2014-09-21 19:33 ` Oleg Nesterov
2014-09-22 6:54 ` Kirill Tkhai
2014-09-24 14:55 ` [tip:sched/core] sched: Fix " tip-bot for Oleg Nesterov
2014-09-21 19:33 ` [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock() Oleg Nesterov
2014-09-21 19:33 ` [PATCH 3/3] sched: print_rq: don't use tasklist_lock Oleg Nesterov
2 siblings, 2 replies; 8+ messages in thread
From: Oleg Nesterov @ 2014-09-21 19:33 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra; +Cc: Kirill Tkhai, Mike Galbraith, linux-kernel
tg_has_rt_tasks() wants to find an RT task in this task_group, but
task_rq(p)->rt.tg wrongly checks the root rt_rq.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/sched/core.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index eee12b3..9023f56 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7354,7 +7354,7 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
struct task_struct *g, *p;
for_each_process_thread(g, p) {
- if (rt_task(p) && task_rq(p)->rt.tg == tg)
+ if (rt_task(p) && task_group(p) == tg)
return 1;
}
--
1.5.5.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock()
2014-09-21 19:33 [PATCH 0/3] sched: fix tg_has_rt_tasks(), tasklist_lock cleanups Oleg Nesterov
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
@ 2014-09-21 19:33 ` Oleg Nesterov
2014-09-24 14:56 ` [tip:sched/core] sched: normalize_rt_tasks(): Don' t " tip-bot for Oleg Nesterov
2014-09-21 19:33 ` [PATCH 3/3] sched: print_rq: don't use tasklist_lock Oleg Nesterov
2 siblings, 1 reply; 8+ messages in thread
From: Oleg Nesterov @ 2014-09-21 19:33 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra; +Cc: Kirill Tkhai, Mike Galbraith, linux-kernel
1. read_lock(tasklist_lock) does not need to disable irqs.
2. ->mm != NULL is the common mistake, use PF_KTHREAD.
3. The second ->mm check can be simply removed.
4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) +
__task_rq_lock().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/sched/core.c | 16 ++++++----------
1 files changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8a6506f..eee12b3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7137,12 +7137,12 @@ void normalize_rt_tasks(void)
unsigned long flags;
struct rq *rq;
- read_lock_irqsave(&tasklist_lock, flags);
+ read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
/*
* Only normalize user tasks:
*/
- if (!p->mm)
+ if (p->flags & PF_KTHREAD)
continue;
p->se.exec_start = 0;
@@ -7157,20 +7157,16 @@ void normalize_rt_tasks(void)
* Renice negative nice level userspace
* tasks back to 0:
*/
- if (task_nice(p) < 0 && p->mm)
+ if (task_nice(p) < 0)
set_user_nice(p, 0);
continue;
}
- raw_spin_lock(&p->pi_lock);
- rq = __task_rq_lock(p);
-
+ rq = task_rq_lock(p, &flags);
normalize_task(rq, p);
-
- __task_rq_unlock(rq);
- raw_spin_unlock(&p->pi_lock);
+ task_rq_unlock(rq, p, &flags);
}
- read_unlock_irqrestore(&tasklist_lock, flags);
+ read_unlock(&tasklist_lock);
}
#endif /* CONFIG_MAGIC_SYSRQ */
--
1.5.5.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [PATCH 3/3] sched: print_rq: don't use tasklist_lock
2014-09-21 19:33 [PATCH 0/3] sched: fix tg_has_rt_tasks(), tasklist_lock cleanups Oleg Nesterov
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
2014-09-21 19:33 ` [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock() Oleg Nesterov
@ 2014-09-21 19:33 ` Oleg Nesterov
2014-09-24 14:56 ` [tip:sched/core] sched: print_rq(): Don't " tip-bot for Oleg Nesterov
2 siblings, 1 reply; 8+ messages in thread
From: Oleg Nesterov @ 2014-09-21 19:33 UTC (permalink / raw)
To: Ingo Molnar, Peter Zijlstra; +Cc: Kirill Tkhai, Mike Galbraith, linux-kernel
read_lock_irqsave(tasklist_lock) in print_rq() looks strange. We do
not need to disable irqs, and they are already disabled by the caller.
And afaics this lock buys nothing, we can rely on rcu_read_lock().
In this case it makes sense to also move rcu_read_lock/unlock from
the caller to print_rq().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/sched/debug.c | 7 ++-----
1 files changed, 2 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c7fe1ea..ce33780 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -150,7 +150,6 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
{
struct task_struct *g, *p;
- unsigned long flags;
SEQ_printf(m,
"\nrunnable tasks:\n"
@@ -159,14 +158,14 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
"------------------------------------------------------"
"----------------------------------------------------\n");
- read_lock_irqsave(&tasklist_lock, flags);
+ rcu_read_lock();
for_each_process_thread(g, p) {
if (task_cpu(p) != rq_cpu)
continue;
print_task(m, rq, p);
}
- read_unlock_irqrestore(&tasklist_lock, flags);
+ rcu_read_unlock();
}
void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
@@ -331,9 +330,7 @@ do { \
print_cfs_stats(m, cpu);
print_rt_stats(m, cpu);
- rcu_read_lock();
print_rq(m, rq, cpu);
- rcu_read_unlock();
spin_unlock_irqrestore(&sched_debug_lock, flags);
SEQ_printf(m, "\n");
}
--
1.5.5.1
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks()
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
@ 2014-09-22 6:54 ` Kirill Tkhai
2014-09-24 14:55 ` [tip:sched/core] sched: Fix " tip-bot for Oleg Nesterov
1 sibling, 0 replies; 8+ messages in thread
From: Kirill Tkhai @ 2014-09-22 6:54 UTC (permalink / raw)
To: Oleg Nesterov; +Cc: Ingo Molnar, Peter Zijlstra, Mike Galbraith, linux-kernel
В Вс, 21/09/2014 в 21:33 +0200, Oleg Nesterov пишет:
> tg_has_rt_tasks() wants to find an RT task in this task_group, but
> task_rq(p)->rt.tg wrongly checks the root rt_rq.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@parallels.com>
> ---
> kernel/sched/core.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index eee12b3..9023f56 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7354,7 +7354,7 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
> struct task_struct *g, *p;
>
> for_each_process_thread(g, p) {
> - if (rt_task(p) && task_rq(p)->rt.tg == tg)
> + if (rt_task(p) && task_group(p) == tg)
> return 1;
> }
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [tip:sched/core] sched: Fix the task-group check in tg_has_rt_tasks()
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
2014-09-22 6:54 ` Kirill Tkhai
@ 2014-09-24 14:55 ` tip-bot for Oleg Nesterov
1 sibling, 0 replies; 8+ messages in thread
From: tip-bot for Oleg Nesterov @ 2014-09-24 14:55 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, ktkhai, hpa, mingo, peterz, umgwanakikbuti, tglx, oleg
Commit-ID: 8651c65844e93af44554272b7e0d2b142837b244
Gitweb: http://git.kernel.org/tip/8651c65844e93af44554272b7e0d2b142837b244
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Sun, 21 Sep 2014 21:33:36 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 Sep 2014 14:47:00 +0200
sched: Fix the task-group check in tg_has_rt_tasks()
tg_has_rt_tasks() wants to find an RT task in this task_group, but
task_rq(p)->rt.tg wrongly checks the root rt_rq.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Link: http://lkml.kernel.org/r/20140921193336.GA28618@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 09bde2a..0abfb7e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7441,7 +7441,7 @@ static inline int tg_has_rt_tasks(struct task_group *tg)
struct task_struct *g, *p;
for_each_process_thread(g, p) {
- if (rt_task(p) && task_rq(p)->rt.tg == tg)
+ if (rt_task(p) && task_group(p) == tg)
return 1;
}
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [tip:sched/core] sched: normalize_rt_tasks(): Don' t use _irqsave for tasklist_lock, use task_rq_lock()
2014-09-21 19:33 ` [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock() Oleg Nesterov
@ 2014-09-24 14:56 ` tip-bot for Oleg Nesterov
0 siblings, 0 replies; 8+ messages in thread
From: tip-bot for Oleg Nesterov @ 2014-09-24 14:56 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, torvalds, peterz, umgwanakikbuti,
tkhai, tglx, oleg
Commit-ID: 3472eaa1f12e217e2b8b0ef658ff861b2308cbbd
Gitweb: http://git.kernel.org/tip/3472eaa1f12e217e2b8b0ef658ff861b2308cbbd
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Sun, 21 Sep 2014 21:33:38 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 Sep 2014 14:47:03 +0200
sched: normalize_rt_tasks(): Don't use _irqsave for tasklist_lock, use task_rq_lock()
1. read_lock(tasklist_lock) does not need to disable irqs.
2. ->mm != NULL is a common mistake, use PF_KTHREAD.
3. The second ->mm check can be simply removed.
4. task_rq_lock() looks better than raw_spin_lock(&p->pi_lock) +
__task_rq_lock().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921193338.GA28621@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/core.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0abfb7e..d65566d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7220,12 +7220,12 @@ void normalize_rt_tasks(void)
unsigned long flags;
struct rq *rq;
- read_lock_irqsave(&tasklist_lock, flags);
+ read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
/*
* Only normalize user tasks:
*/
- if (!p->mm)
+ if (p->flags & PF_KTHREAD)
continue;
p->se.exec_start = 0;
@@ -7240,20 +7240,16 @@ void normalize_rt_tasks(void)
* Renice negative nice level userspace
* tasks back to 0:
*/
- if (task_nice(p) < 0 && p->mm)
+ if (task_nice(p) < 0)
set_user_nice(p, 0);
continue;
}
- raw_spin_lock(&p->pi_lock);
- rq = __task_rq_lock(p);
-
+ rq = task_rq_lock(p, &flags);
normalize_task(rq, p);
-
- __task_rq_unlock(rq);
- raw_spin_unlock(&p->pi_lock);
+ task_rq_unlock(rq, p, &flags);
}
- read_unlock_irqrestore(&tasklist_lock, flags);
+ read_unlock(&tasklist_lock);
}
#endif /* CONFIG_MAGIC_SYSRQ */
^ permalink raw reply related [flat|nested] 8+ messages in thread
* [tip:sched/core] sched: print_rq(): Don't use tasklist_lock
2014-09-21 19:33 ` [PATCH 3/3] sched: print_rq: don't use tasklist_lock Oleg Nesterov
@ 2014-09-24 14:56 ` tip-bot for Oleg Nesterov
0 siblings, 0 replies; 8+ messages in thread
From: tip-bot for Oleg Nesterov @ 2014-09-24 14:56 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, torvalds, peterz, umgwanakikbuti,
tkhai, tglx, oleg
Commit-ID: 5bd96ab6fef66ec6b9f54134364e618fd0f8f2f3
Gitweb: http://git.kernel.org/tip/5bd96ab6fef66ec6b9f54134364e618fd0f8f2f3
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Sun, 21 Sep 2014 21:33:41 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 Sep 2014 14:47:04 +0200
sched: print_rq(): Don't use tasklist_lock
read_lock_irqsave(tasklist_lock) in print_rq() looks strange. We do
not need to disable irqs, and they are already disabled by the caller.
And afaics this lock buys nothing, we can rely on rcu_read_lock().
In this case it makes sense to also move rcu_read_lock/unlock from
the caller to print_rq().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140921193341.GA28628@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/debug.c | 7 ++-----
1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index c7fe1ea0..ce33780 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -150,7 +150,6 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
{
struct task_struct *g, *p;
- unsigned long flags;
SEQ_printf(m,
"\nrunnable tasks:\n"
@@ -159,14 +158,14 @@ static void print_rq(struct seq_file *m, struct rq *rq, int rq_cpu)
"------------------------------------------------------"
"----------------------------------------------------\n");
- read_lock_irqsave(&tasklist_lock, flags);
+ rcu_read_lock();
for_each_process_thread(g, p) {
if (task_cpu(p) != rq_cpu)
continue;
print_task(m, rq, p);
}
- read_unlock_irqrestore(&tasklist_lock, flags);
+ rcu_read_unlock();
}
void print_cfs_rq(struct seq_file *m, int cpu, struct cfs_rq *cfs_rq)
@@ -331,9 +330,7 @@ do { \
print_cfs_stats(m, cpu);
print_rt_stats(m, cpu);
- rcu_read_lock();
print_rq(m, rq, cpu);
- rcu_read_unlock();
spin_unlock_irqrestore(&sched_debug_lock, flags);
SEQ_printf(m, "\n");
}
^ permalink raw reply related [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-09-24 15:06 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2014-09-21 19:33 [PATCH 0/3] sched: fix tg_has_rt_tasks(), tasklist_lock cleanups Oleg Nesterov
2014-09-21 19:33 ` [PATCH 1/3] sched: fix the task-group check in tg_has_rt_tasks() Oleg Nesterov
2014-09-22 6:54 ` Kirill Tkhai
2014-09-24 14:55 ` [tip:sched/core] sched: Fix " tip-bot for Oleg Nesterov
2014-09-21 19:33 ` [PATCH 2/3] sched: normalize_rt_tasks: don't use _irqsave for tasklist_lock, use task_rq_lock() Oleg Nesterov
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