This is a note to let you know that I've just added the patch titled
cgroup/cpuset: Free DL BW in case can_attach() fails
to the 6.4-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:
cgroup-cpuset-free-dl-bw-in-case-can_attach-fails.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable-owner@xxxxxxxxxxxxxxx Tue Aug 22 00:20:48 2023
From: Qais Yousef <qyousef@xxxxxxxxxxx>
Date: Mon, 21 Aug 2023 23:19:56 +0100
Subject: cgroup/cpuset: Free DL BW in case can_attach() fails
To: stable@xxxxxxxxxxxxxxx
Cc: Juri Lelli <juri.lelli@xxxxxxxxxx>, Waiman Long <longman@xxxxxxxxxx>, Tejun Heo <tj@xxxxxxxxxx>, Dietmar Eggemann <dietmar.eggemann@xxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Vincent Guittot <vincent.guittot@xxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Hao Luo <haoluo@xxxxxxxxxx>, John Stultz <jstultz@xxxxxxxxxx>, cgroups@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, Qais Yousef <qyousef@xxxxxxxxxxx>
Message-ID: <20230821221956.698117-7-qyousef@xxxxxxxxxxx>
From: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
commit 2ef269ef1ac006acf974793d975539244d77b28f upstream.
cpuset_can_attach() can fail. Postpone DL BW allocation until all tasks
have been checked. DL BW is not allocated per-task but as a sum over
all DL tasks migrating.
If multiple controllers are attached to the cgroup next to the cpuset
controller a non-cpuset can_attach() can fail. In this case free DL BW
in cpuset_cancel_attach().
Finally, update cpuset DL task count (nr_deadline_tasks) only in
cpuset_attach().
Suggested-by: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx>
Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Qais Yousef (Google) <qyousef@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/sched.h | 2 -
kernel/cgroup/cpuset.c | 53 ++++++++++++++++++++++++++++++++++++++++++++-----
kernel/sched/core.c | 17 +--------------
3 files changed, 51 insertions(+), 21 deletions(-)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1852,7 +1852,7 @@ current_restore_flags(unsigned long orig
}
extern int cpuset_cpumask_can_shrink(const struct cpumask *cur, const struct cpumask *trial);
-extern int task_can_attach(struct task_struct *p, const struct cpumask *cs_effective_cpus);
+extern int task_can_attach(struct task_struct *p);
extern int dl_bw_alloc(int cpu, u64 dl_bw);
extern void dl_bw_free(int cpu, u64 dl_bw);
#ifdef CONFIG_SMP
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -198,6 +198,8 @@ struct cpuset {
* know when to rebuild associated root domain bandwidth information.
*/
int nr_deadline_tasks;
+ int nr_migrate_dl_tasks;
+ u64 sum_migrate_dl_bw;
/* Invalid partition error code, not lock protected */
enum prs_errcode prs_err;
@@ -2496,16 +2498,23 @@ static int cpuset_can_attach_check(struc
return 0;
}
+static void reset_migrate_dl_data(struct cpuset *cs)
+{
+ cs->nr_migrate_dl_tasks = 0;
+ cs->sum_migrate_dl_bw = 0;
+}
+
/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
static int cpuset_can_attach(struct cgroup_taskset *tset)
{
struct cgroup_subsys_state *css;
- struct cpuset *cs;
+ struct cpuset *cs, *oldcs;
struct task_struct *task;
int ret;
/* used later by cpuset_attach() */
cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
+ oldcs = cpuset_attach_old_cs;
cs = css_cs(css);
mutex_lock(&cpuset_mutex);
@@ -2516,7 +2525,7 @@ static int cpuset_can_attach(struct cgro
goto out_unlock;
cgroup_taskset_for_each(task, css, tset) {
- ret = task_can_attach(task, cs->effective_cpus);
+ ret = task_can_attach(task);
if (ret)
goto out_unlock;
ret = security_task_setscheduler(task);
@@ -2524,11 +2533,31 @@ static int cpuset_can_attach(struct cgro
goto out_unlock;
if (dl_task(task)) {
- cs->nr_deadline_tasks++;
- cpuset_attach_old_cs->nr_deadline_tasks--;
+ cs->nr_migrate_dl_tasks++;
+ cs->sum_migrate_dl_bw += task->dl.dl_bw;
}
}
+ if (!cs->nr_migrate_dl_tasks)
+ goto out_success;
+
+ if (!cpumask_intersects(oldcs->effective_cpus, cs->effective_cpus)) {
+ int cpu = cpumask_any_and(cpu_active_mask, cs->effective_cpus);
+
+ if (unlikely(cpu >= nr_cpu_ids)) {
+ reset_migrate_dl_data(cs);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ ret = dl_bw_alloc(cpu, cs->sum_migrate_dl_bw);
+ if (ret) {
+ reset_migrate_dl_data(cs);
+ goto out_unlock;
+ }
+ }
+
+out_success:
/*
* Mark attach is in progress. This makes validate_change() fail
* changes which zero cpus/mems_allowed.
@@ -2551,6 +2580,14 @@ static void cpuset_cancel_attach(struct
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
+
+ if (cs->nr_migrate_dl_tasks) {
+ int cpu = cpumask_any(cs->effective_cpus);
+
+ dl_bw_free(cpu, cs->sum_migrate_dl_bw);
+ reset_migrate_dl_data(cs);
+ }
+
mutex_unlock(&cpuset_mutex);
}
@@ -2651,6 +2688,12 @@ static void cpuset_attach(struct cgroup_
out:
cs->old_mems_allowed = cpuset_attach_nodemask_to;
+ if (cs->nr_migrate_dl_tasks) {
+ cs->nr_deadline_tasks += cs->nr_migrate_dl_tasks;
+ oldcs->nr_deadline_tasks -= cs->nr_migrate_dl_tasks;
+ reset_migrate_dl_data(cs);
+ }
+
cs->attach_in_progress--;
if (!cs->attach_in_progress)
wake_up(&cpuset_attach_wq);
@@ -3330,7 +3373,7 @@ static int cpuset_can_fork(struct task_s
if (ret)
goto out_unlock;
- ret = task_can_attach(task, cs->effective_cpus);
+ ret = task_can_attach(task);
if (ret)
goto out_unlock;
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -9294,8 +9294,7 @@ int cpuset_cpumask_can_shrink(const stru
return ret;
}
-int task_can_attach(struct task_struct *p,
- const struct cpumask *cs_effective_cpus)
+int task_can_attach(struct task_struct *p)
{
int ret = 0;
@@ -9308,21 +9307,9 @@ int task_can_attach(struct task_struct *
* success of set_cpus_allowed_ptr() on all attached tasks
* before cpus_mask may be changed.
*/
- if (p->flags & PF_NO_SETAFFINITY) {
+ if (p->flags & PF_NO_SETAFFINITY)
ret = -EINVAL;
- goto out;
- }
- if (dl_task(p) && !cpumask_intersects(task_rq(p)->rd->span,
- cs_effective_cpus)) {
- int cpu = cpumask_any_and(cpu_active_mask, cs_effective_cpus);
-
- if (unlikely(cpu >= nr_cpu_ids))
- return -EINVAL;
- ret = dl_bw_alloc(cpu, p->dl.dl_bw);
- }
-
-out:
return ret;
}
Patches currently in stable-queue which might be from stable-owner@xxxxxxxxxxxxxxx are
queue-6.4/cgroup-cpuset-free-dl-bw-in-case-can_attach-fails.patch
queue-6.4/sched-cpuset-keep-track-of-sched_deadline-task-in-cpusets.patch
queue-6.4/cgroup-cpuset-rename-functions-dealing-with-deadline-accounting.patch
queue-6.4/cgroup-cpuset-iterate-only-if-deadline-tasks-are-present.patch
queue-6.4/sched-cpuset-bring-back-cpuset_mutex.patch
queue-6.4/sched-deadline-create-dl-bw-alloc-free-check-overflow-interface.patch
