rcu: Disable laziness if lazy-tracking says so

During suspend, we see failures to suspend 1 in 300-500 suspends.
Looking closer, it appears that asynchronous RCU callbacks are being
queued as lazy even though synchronous callbacks are expedited. These
delays appear to not be very welcome by the suspend/resume code as
evidenced by these occasional suspend failures.

This commit modifies call_rcu() to check if rcu_async_should_hurry(),
which will return true if we are in suspend or in-kernel boot.

[ paulmck: Alphabetize local variables. ]

Ignoring the lazy hint makes the 3000 suspend/resume cycles pass
reliably on a 12th gen 12-core Intel CPU, and there is some evidence
that it also slightly speeds up boot performance.

Fixes: 3cb278e73be5 ("rcu: Make call_rcu() lazy to save power")
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 712c4e7..4374d7a 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2575,10 +2575,11 @@ static void check_cb_ovld(struct rcu_data *rdp)
 }
 
 static void
-__call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy)
+__call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy_in)
 {
        static atomic_t doublefrees;
        unsigned long flags;
+       bool lazy;
        struct rcu_data *rdp;
        bool was_alldone;
 
@@ -2603,6 +2604,7 @@ __call_rcu_common(struct rcu_head *head, rcu_callback_t func, bool lazy)
        kasan_record_aux_stack_noalloc(head);
        local_irq_save(flags);
        rdp = this_cpu_ptr(&rcu_data);
+       lazy = lazy_in && !rcu_async_should_hurry();
 
        /* Add the callback to our list. */
        if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist))) {