From: "tip-bot2 for Mathieu Desnoyers" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Chris Metcalf <cmetcalf@ezchip.com>,
Christoph Lameter <cl@linux.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Kirill Tkhai <tkhai@yandex.ru>,
Linus Torvalds <torvalds@linux-foundation.org>,
Mike Galbraith <efault@gmx.de>, Oleg Nesterov <oleg@redhat.com>,
"Paul E. McKenney" <paulmck@linux.ibm.com>,
"Russell King - ARM Linux admin" <linux@armlinux.org.uk>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@alien8.de>,
linux-kernel@vger.kernel.org
Subject: [tip: sched/urgent] sched/membarrier: Skip IPIs when mm->mm_users == 1
Date: Fri, 27 Sep 2019 08:10:42 -0000 [thread overview]
Message-ID: <156957184275.9866.9051290983348883537.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20190919173705.2181-7-mathieu.desnoyers@efficios.com>
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: c6d68c1c4a4d6611fc0f8145d764226571d737ca
Gitweb: https://git.kernel.org/tip/c6d68c1c4a4d6611fc0f8145d764226571d737ca
Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
AuthorDate: Thu, 19 Sep 2019 13:37:04 -04:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 25 Sep 2019 17:42:31 +02:00
sched/membarrier: Skip IPIs when mm->mm_users == 1
If there is only a single mm_user for the mm, the private expedited
membarrier command can skip the IPIs, because only a single thread
is using the mm.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190919173705.2181-7-mathieu.desnoyers@efficios.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/membarrier.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index 070cf43..fced54a 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -145,20 +145,21 @@ static int membarrier_private_expedited(int flags)
int cpu;
bool fallback = false;
cpumask_var_t tmpmask;
+ struct mm_struct *mm = current->mm;
if (flags & MEMBARRIER_FLAG_SYNC_CORE) {
if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE))
return -EINVAL;
- if (!(atomic_read(¤t->mm->membarrier_state) &
+ if (!(atomic_read(&mm->membarrier_state) &
MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY))
return -EPERM;
} else {
- if (!(atomic_read(¤t->mm->membarrier_state) &
+ if (!(atomic_read(&mm->membarrier_state) &
MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY))
return -EPERM;
}
- if (num_online_cpus() == 1)
+ if (atomic_read(&mm->mm_users) == 1 || num_online_cpus() == 1)
return 0;
/*
@@ -194,7 +195,7 @@ static int membarrier_private_expedited(int flags)
continue;
rcu_read_lock();
p = rcu_dereference(cpu_rq(cpu)->curr);
- if (p && p->mm == current->mm) {
+ if (p && p->mm == mm) {
if (!fallback)
__cpumask_set_cpu(cpu, tmpmask);
else
next prev parent reply other threads:[~2019-09-27 8:11 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 17:36 [RFC PATCH for 5.4 0/7] Membarrier fixes and cleanups Mathieu Desnoyers
2019-09-19 17:36 ` [RFC PATCH for 5.4 1/7] Fix: sched/membarrier: Private expedited registration check Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Fix private " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 2/7] Cleanup: sched/membarrier: Remove redundant check Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 3/7] Cleanup: sched/membarrier: Only sync_core before usermode for same mm Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Call sync_core only " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 4/7] Fix: sched/membarrier: p->mm->membarrier_state racy load (v4) Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] sched/membarrier: Fix p->mm->membarrier_state racy load tip-bot2 for Mathieu Desnoyers
2019-10-01 8:44 ` Ingo Molnar
2019-10-01 8:50 ` Peter Zijlstra
2019-10-01 19:34 ` [tip: sched/urgent] membarrier: Fix RCU locking bug caused by faulty merge tip-bot2 for Peter Zijlstra
2019-09-19 17:37 ` [RFC PATCH for 5.4 5/7] selftests: sched/membarrier: Add multi-threaded test Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] selftests, " tip-bot2 for Mathieu Desnoyers
2019-09-19 17:37 ` [RFC PATCH for 5.4 6/7] sched/membarrier: Skip IPIs when mm->mm_users == 1 Mathieu Desnoyers
2019-09-27 8:10 ` tip-bot2 for Mathieu Desnoyers [this message]
2019-09-19 17:37 ` [RFC PATCH for 5.4 7/7] sched/membarrier: Return -ENOMEM to userspace on memory allocation failure Mathieu Desnoyers
2019-09-27 8:10 ` [tip: sched/urgent] " tip-bot2 for Mathieu Desnoyers
2019-09-23 9:06 ` [RFC PATCH for 5.4 0/7] Membarrier fixes and cleanups Peter Zijlstra
2019-09-23 14:55 ` Mathieu Desnoyers
2019-09-25 8:07 ` Peter Zijlstra
2019-09-25 15:50 ` Mathieu Desnoyers
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