From: Peter Zijlstra <peterz@infradead.org> mainline inclusion from mainline-5.4-rc2 commit 73956fc07dd7b25d4a33ab3fdd6247c60d0b237c category: bugfix bugzilla: 28332 CVE: NA ------------------------------------------------- The following commit: 227a4aadc75b ("sched/membarrier: Fix p->mm->membarrier_state racy load") got fat fingered by me when merging it with other patches. It meant to move the RCU section out of the for loop but ended up doing it partially, leaving a superfluous rcu_read_lock() inside, causing havok. Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Borislav Petkov <bp@alien8.de> 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: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> 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> Cc: linux-tip-commits@vger.kernel.org Fixes: 227a4aadc75b ("sched/membarrier: Fix p->mm->membarrier_state racy load") Link: https://lkml.kernel.org/r/20191001085033.GP4519@hirez.programming.kicks-ass.... Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com> Reviewed-By: Xie XiuQi <xiexiuqi@huawei.com> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> --- kernel/sched/membarrier.c | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 436c427..c4ea07e 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -183,7 +183,6 @@ static int membarrier_private_expedited(int flags) */ if (cpu == raw_smp_processor_id()) continue; - rcu_read_lock(); p = task_rcu_dereference(&cpu_rq(cpu)->curr); if (p && p->mm == mm) __cpumask_set_cpu(cpu, tmpmask); -- 1.8.3