From: "Paul E. McKenney" <[email protected]> Currently, synchronize_sched_expedited() will call synchronize_sched() if there is danger of counter wrap. But if configuration says to always do expedited grace periods, synchronize_sched() will just call synchronize_sched_expedited() right back again. In theory, the old expedited operations will complete, the counters will get back in synch, and the recursion will end. But we could easily run out of stack long before that time. This commit therefore makes synchronize_sched_expedited() invoke the underlying wait_rcu_gp(call_rcu_sched) instead of synchronize_sched(), the same as all the other calls out from synchronize_sched_expedited().
This bug was introduced by commit 1924bcb02597 (Avoid counter wrap in synchronize_sched_expedited()). Reported-by: Rik van Riel <[email protected]> Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 5b573e75e0f8..647dee075d99 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3288,7 +3288,7 @@ void synchronize_sched_expedited(void) if (ULONG_CMP_GE((ulong)atomic_long_read(&rsp->expedited_start), (ulong)atomic_long_read(&rsp->expedited_done) + ULONG_MAX / 8)) { - synchronize_sched(); + wait_rcu_gp(call_rcu_sched); atomic_long_inc(&rsp->expedited_wrap); return; } -- 1.8.1.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
