[PATCH 6.12 0878/1376] block/kyber-iosched: flush per-cpu latency buckets over possible CPUs

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Tao Cui <cuitao@kylinos.cn>

[ Upstream commit 482fc257de95ab181688e9d1dfcc6b6a58857b1e ]

kyber_timer_fn() sums the per-cpu latency histograms with
for_each_online_cpu().  A CPU that goes offline mid-interval leaves its
bucket un-flushed; the samples are lost from the current decision and
re-appear (stale) when the CPU is onlined again.

Fixes: 6e25cb01ea20 ("kyber: implement improved heuristics")
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/20260720093726.28965-5-cui.tao@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/kyber-iosched.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index ccfefa6a36696..869e83054c48f 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -279,7 +279,7 @@ static void kyber_timer_fn(struct timer_list *t)
 	bool bad = false;
 
 	/* Sum all of the per-cpu latency histograms. */
-	for_each_online_cpu(cpu) {
+	for_each_possible_cpu(cpu) {
 		struct kyber_cpu_latency *cpu_latency;
 
 		cpu_latency = per_cpu_ptr(kqd->cpu_latency, cpu);
-- 
2.53.0