From: tip-bot for Oleg Nesterov <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org,
ktkhai@parallels.com, tkhai@yandex.ru, oleg@redhat.com,
efault@gmx.de, mingo@kernel.org, peterz@infradead.org,
torvalds@linux-foundation.org, cl@linux.com,
vdavydov@parallels.com, hpa@zytor.com, cmetcalf@ezchip.com
Subject: [tip:sched/core] sched/fair: Use task_rcu_dereference()
Date: Fri, 3 Jun 2016 03:49:03 -0700 [thread overview]
Message-ID: <tip-bac7857319bcf7fed329a10bb760053e761115c0@git.kernel.org> (raw)
In-Reply-To: <20160518195733.GA15914@redhat.com>
Commit-ID: bac7857319bcf7fed329a10bb760053e761115c0
Gitweb: http://git.kernel.org/tip/bac7857319bcf7fed329a10bb760053e761115c0
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Wed, 18 May 2016 21:57:33 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 3 Jun 2016 09:18:58 +0200
sched/fair: Use task_rcu_dereference()
Simplify task_numa_compare()'s task reference magic by using
task_rcu_dereference().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vladimir Davydov <vdavydov@parallels.com>
Link: http://lkml.kernel.org/r/20160518195733.GA15914@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/fair.c | 34 ++++------------------------------
1 file changed, 4 insertions(+), 30 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 1e87bb6..c6dd8ba 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1305,6 +1305,8 @@ static void task_numa_assign(struct task_numa_env *env,
{
if (env->best_task)
put_task_struct(env->best_task);
+ if (p)
+ get_task_struct(p);
env->best_task = p;
env->best_imp = imp;
@@ -1372,31 +1374,11 @@ static void task_numa_compare(struct task_numa_env *env,
long imp = env->p->numa_group ? groupimp : taskimp;
long moveimp = imp;
int dist = env->dist;
- bool assigned = false;
rcu_read_lock();
-
- raw_spin_lock_irq(&dst_rq->lock);
- cur = dst_rq->curr;
- /*
- * No need to move the exiting task or idle task.
- */
- if ((cur->flags & PF_EXITING) || is_idle_task(cur))
+ cur = task_rcu_dereference(&dst_rq->curr);
+ if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur)))
cur = NULL;
- else {
- /*
- * The task_struct must be protected here to protect the
- * p->numa_faults access in the task_weight since the
- * numa_faults could already be freed in the following path:
- * finish_task_switch()
- * --> put_task_struct()
- * --> __put_task_struct()
- * --> task_numa_free()
- */
- get_task_struct(cur);
- }
-
- raw_spin_unlock_irq(&dst_rq->lock);
/*
* Because we have preemption enabled we can get migrated around and
@@ -1479,7 +1461,6 @@ balance:
*/
if (!load_too_imbalanced(src_load, dst_load, env)) {
imp = moveimp - 1;
- put_task_struct(cur);
cur = NULL;
goto assign;
}
@@ -1505,16 +1486,9 @@ balance:
env->dst_cpu = select_idle_sibling(env->p, env->dst_cpu);
assign:
- assigned = true;
task_numa_assign(env, cur, imp);
unlock:
rcu_read_unlock();
- /*
- * The dst_rq->curr isn't assigned. The protection for task_struct is
- * finished.
- */
- if (cur && !assigned)
- put_task_struct(cur);
}
static void task_numa_find_cpu(struct task_numa_env *env,
next prev parent reply other threads:[~2016-06-03 10:49 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-22 7:17 [PATCH v4] sched/numa: fix unsafe get_task_struct() in task_numa_assign() Kirill Tkhai
2014-10-22 21:30 ` introduce task_rcu_dereference? Oleg Nesterov
2014-10-22 22:23 ` Oleg Nesterov
2014-10-23 18:15 ` Oleg Nesterov
2014-10-23 8:10 ` Kirill Tkhai
2014-10-23 18:18 ` Oleg Nesterov
2014-10-24 7:51 ` Kirill Tkhai
2014-10-27 19:53 ` [PATCH 0/3] introduce task_rcu_dereference() Oleg Nesterov
2014-10-27 19:54 ` [PATCH 1/3] probe_kernel_address() can use __probe_kernel_read() Oleg Nesterov
2014-10-27 19:54 ` [PATCH 2/3] introduce probe_slab_address() Oleg Nesterov
2014-10-27 19:21 ` Christoph Lameter
2014-10-28 5:44 ` Kirill Tkhai
2014-10-28 5:48 ` Kirill Tkhai
2014-10-28 15:01 ` Peter Zijlstra
2014-10-28 17:56 ` Kirill Tkhai
2014-10-28 18:00 ` Kirill Tkhai
2014-10-28 19:55 ` Oleg Nesterov
2014-10-28 20:12 ` Oleg Nesterov
2014-10-29 5:10 ` Kirill Tkhai
2014-10-27 19:54 ` [PATCH 3/3] introduce task_rcu_dereference() Oleg Nesterov
2014-10-28 6:22 ` Kirill Tkhai
2016-05-18 17:02 ` Peter Zijlstra
2016-05-18 18:23 ` Oleg Nesterov
2016-05-18 19:10 ` Peter Zijlstra
2016-05-18 19:57 ` Oleg Nesterov
2016-05-26 11:34 ` Peter Zijlstra
2016-06-03 10:49 ` tip-bot for Oleg Nesterov [this message]
2016-06-03 10:48 ` [tip:sched/core] sched/api: Introduce task_rcu_dereference() and try_get_task_struct() tip-bot for Oleg Nesterov
2014-10-28 11:02 ` [tip:sched/core] sched/numa: Fix unsafe get_task_struct() in task_numa_assign() tip-bot for Kirill Tkhai
2014-11-08 3:48 ` [PATCH v4] sched/numa: fix " Sasha Levin
2014-11-09 14:07 ` Kirill Tkhai
2014-11-10 10:03 ` Peter Zijlstra
2014-11-10 15:48 ` Sasha Levin
2014-11-10 16:01 ` Peter Zijlstra
2014-11-16 9:50 ` [tip:sched/urgent] sched/numa: Avoid selecting oneself as swap target tip-bot for Peter Zijlstra
2014-11-10 16:03 ` [PATCH v4] sched/numa: fix unsafe get_task_struct() in task_numa_assign() Peter Zijlstra
2014-11-10 16:09 ` Sasha Levin
2014-11-10 16:16 ` Peter Zijlstra
2014-11-10 16:10 ` Kirill Tkhai
2014-11-10 16:36 ` Kirill Tkhai
2014-11-10 16:44 ` Sasha Levin
2014-11-10 20:01 ` Kirill Tkhai
2014-11-12 9:49 ` Kirill Tkhai
2014-11-15 2:38 ` Sasha Levin
2014-11-18 17:30 ` Sasha Levin
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