From: Mathieu Desnoyers mathieu.desnoyers@efficios.com
[ Upstream commit fc0d77387cb5ae883fd774fc559e056a8dde024c ]
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 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/20190919173705.2181-2-mathieu.desnoyers@efficios.c... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@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 76e0eaf4654e0..dd27e632b1bab 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -235,7 +235,7 @@ 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)