During suspend, we see failures to suspend 1 in 300-500 suspends.
Looking closer, it appears that we are queuing lazy callbacks even
though rcu_gp_is_expedited(). These delays appear to not be very welcome
by the suspend/resume code as evidenced by these occasional suspend
failures.
This commit therefore checks if rcu_gp_is_expedited() and ignores the
lazy hint if so.
Ignoring the lazy hint if rcu_gp_is_expedited() makes the 3000
suspend/resume cycles pass reliably on a 12th gen 12-core Intel CPU.
Fixes: 3cb278e73be5 ("rcu: Make call_rcu() lazy to save power")
Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
Paul, could we take this for 6.2 -rc cycle? Thanks.
kernel/rcu/tree.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 63545d79da51..93eb03f8ed99 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2594,12 +2594,12 @@ 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;
struct rcu_data *rdp;
- bool was_alldone;
+ bool was_alldone, lazy;
/* Misaligned rcu_head! */
WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1));
@@ -2622,6 +2622,7 @@ __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_gp_is_expedited();
/* Add the callback to our list. */
if (unlikely(!rcu_segcblist_is_enabled(&rdp->cblist))) {
--
2.39.0.314.g84b9a713c41-goog
