From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Russell King - ARM Linux admin <linux@armlinux.org.uk>,
Chris Metcalf <cmetcalf@ezchip.com>,
Christoph Lameter <cl@linux.com>, Kirill Tkhai <tkhai@yandex.ru>,
Mike Galbraith <efault@gmx.de>,
Thomas Gleixner <tglx@linutronix.de>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: [RFC PATCH 1/4] Fix: sched/membarrier: private expedited registration check
Date: Thu, 5 Sep 2019 23:12:57 -0400 [thread overview]
Message-ID: <20190906031300.1647-2-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20190906031300.1647-1-mathieu.desnoyers@efficios.com>
Fix a logic flaw in the way membarrier_register_private_expedited()
handles ready state checks for private expedited sync core and private
expedited registrations.
If a private expedited membarrier registration is first performed, and
then a private expedited sync_core registration is performed, the ready
state check will skip the second registration when it really should not.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Kirill Tkhai <tkhai@yandex.ru>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/membarrier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c
index aa8d75804108..5110d91b1b0e 100644
--- a/kernel/sched/membarrier.c
+++ b/kernel/sched/membarrier.c
@@ -226,7 +226,7 @@ static int membarrier_register_private_expedited(int flags)
* groups, which use the same mm. (CLONE_VM but not
* CLONE_THREAD).
*/
- if (atomic_read(&mm->membarrier_state) & state)
+ if ((atomic_read(&mm->membarrier_state) & state) == state)
return 0;
atomic_or(MEMBARRIER_STATE_PRIVATE_EXPEDITED, &mm->membarrier_state);
if (flags & MEMBARRIER_FLAG_SYNC_CORE)
--
2.17.1
next prev parent reply other threads:[~2019-09-06 3:13 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 3:12 [RFC PATCH 0/4] Membarrier fixes/cleanups Mathieu Desnoyers
2019-09-06 3:12 ` Mathieu Desnoyers [this message]
2019-09-06 3:12 ` [RFC PATCH 2/4] Cleanup: sched/membarrier: remove redundant check Mathieu Desnoyers
2019-09-06 3:12 ` [RFC PATCH 3/4] Cleanup: sched/membarrier: only sync_core before usermode for same mm Mathieu Desnoyers
2019-09-06 7:41 ` Peter Zijlstra
2019-09-06 13:40 ` Mathieu Desnoyers
2019-09-06 3:13 ` [RFC PATCH 4/4] Fix: sched/membarrier: p->mm->membarrier_state racy load Mathieu Desnoyers
2019-09-06 8:23 ` Peter Zijlstra
2019-09-08 13:49 ` [RFC PATCH 4/4] Fix: sched/membarrier: p->mm->membarrier_state racy load (v2) Mathieu Desnoyers
2019-09-08 16:51 ` Linus Torvalds
2019-09-10 9:48 ` Mathieu Desnoyers
2019-09-12 13:48 ` Will Deacon
2019-09-12 14:24 ` Linus Torvalds
2019-09-12 15:47 ` Will Deacon
2019-09-13 14:22 ` Mathieu Desnoyers
2019-09-19 16:26 ` Will Deacon
2019-09-19 17:33 ` Mathieu Desnoyers
2019-09-09 11:00 ` Oleg Nesterov
2019-09-13 15:20 ` Mathieu Desnoyers
2019-09-13 16:04 ` Oleg Nesterov
2019-09-13 17:07 ` Mathieu Desnoyers
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