This is a note to let you know that I've just added the patch titled
sched/psi: Use task->psi_flags to clear in CPU migration
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-psi-use-task-psi_flags-to-clear-in-cpu-migrati.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 8c3963a7a694007864917926be335df6aac13f0d
Author: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Date: Mon Sep 26 16:19:31 2022 +0800
sched/psi: Use task->psi_flags to clear in CPU migration
[ Upstream commit 52b33d87b9197c51e8ffdc61873739d90dd0a16f ]
The commit d583d360a620 ("psi: Fix psi state corruption when schedule()
races with cgroup move") fixed a race problem by making cgroup_move_task()
use task->psi_flags instead of looking at the scheduler state.
We can extend task->psi_flags usage to CPU migration, which should be
a minor optimization for performance and code simplicity.
Signed-off-by: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220926081931.45420-1-zhouchengming@xxxxxxxxxxxxx
Stable-dep-of: a430d99e3490 ("sched/fair: Fix value reported by hot tasks pulled in /proc/schedstat")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/sched.h b/include/linux/sched.h
index e87a68b136da9..6c82d71fab113 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -888,9 +888,6 @@ struct task_struct {
unsigned sched_reset_on_fork:1;
unsigned sched_contributes_to_load:1;
unsigned sched_migrated:1;
-#ifdef CONFIG_PSI
- unsigned sched_psi_wake_requeue:1;
-#endif
/* Force alignment to the next boundary: */
unsigned :0;
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 54af671e8d510..f54d2da2f9a67 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2049,7 +2049,7 @@ static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
if (!(flags & ENQUEUE_RESTORE)) {
sched_info_enqueue(rq, p);
- psi_enqueue(p, flags & ENQUEUE_WAKEUP);
+ psi_enqueue(p, (flags & ENQUEUE_WAKEUP) && !(flags & ENQUEUE_MIGRATED));
}
uclamp_rq_inc(rq, p);
diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index b49a96fad1d2f..b02dfc3229510 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -132,11 +132,9 @@ static inline void psi_enqueue(struct task_struct *p, bool wakeup)
if (p->in_memstall)
set |= TSK_MEMSTALL_RUNNING;
- if (!wakeup || p->sched_psi_wake_requeue) {
+ if (!wakeup) {
if (p->in_memstall)
set |= TSK_MEMSTALL;
- if (p->sched_psi_wake_requeue)
- p->sched_psi_wake_requeue = 0;
} else {
if (p->in_iowait)
clear |= TSK_IOWAIT;
@@ -147,8 +145,6 @@ static inline void psi_enqueue(struct task_struct *p, bool wakeup)
static inline void psi_dequeue(struct task_struct *p, bool sleep)
{
- int clear = TSK_RUNNING;
-
if (static_branch_likely(&psi_disabled))
return;
@@ -161,10 +157,7 @@ static inline void psi_dequeue(struct task_struct *p, bool sleep)
if (sleep)
return;
- if (p->in_memstall)
- clear |= (TSK_MEMSTALL | TSK_MEMSTALL_RUNNING);
-
- psi_task_change(p, clear, 0);
+ psi_task_change(p, p->psi_flags, 0);
}
static inline void psi_ttwu_dequeue(struct task_struct *p)
@@ -176,19 +169,12 @@ static inline void psi_ttwu_dequeue(struct task_struct *p)
* deregister its sleep-persistent psi states from the old
* queue, and let psi_enqueue() know it has to requeue.
*/
- if (unlikely(p->in_iowait || p->in_memstall)) {
+ if (unlikely(p->psi_flags)) {
struct rq_flags rf;
struct rq *rq;
- int clear = 0;
-
- if (p->in_iowait)
- clear |= TSK_IOWAIT;
- if (p->in_memstall)
- clear |= TSK_MEMSTALL;
rq = __task_rq_lock(p, &rf);
- psi_task_change(p, clear, 0);
- p->sched_psi_wake_requeue = 1;
+ psi_task_change(p, p->psi_flags, 0);
__task_rq_unlock(rq, &rf);
}
}
