diff options
| author | Guopeng Zhang <zhangguopeng@kylinos.cn> | 2026-04-17 11:37:41 +0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-04-17 08:57:37 -1000 |
| commit | 41d701ddc36d5301b44ea79529f3cf03c541c1e1 (patch) | |
| tree | 523c05c96efdf4fa91257c96bf42b15b0c6e2c51 /kernel | |
| parent | c802f460dd485c1332b5a35e7adcfb2bc22536a2 (diff) | |
cgroup/cpuset: record DL BW alloc CPU for attach rollback
cpuset_can_attach() allocates DL bandwidth only when migrating
deadline tasks to a disjoint CPU mask, but cpuset_cancel_attach()
rolls back based only on nr_migrate_dl_tasks. This makes the DL
bandwidth alloc/free paths asymmetric: rollback can call dl_bw_free()
even when no dl_bw_alloc() was done.
Rollback also needs to undo the reservation against the same CPU/root
domain that was charged. Record the CPU used by dl_bw_alloc() and use
that state in cpuset_cancel_attach(). If no allocation happened,
dl_bw_cpu stays at -1 and rollback skips dl_bw_free(). If allocation
did happen, bandwidth is returned to the same CPU/root domain.
Successful attach paths are unchanged. This only fixes failed attach
rollback accounting.
Fixes: 2ef269ef1ac0 ("cgroup/cpuset: Free DL BW in case can_attach() fails")
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cpuset-internal.h | 5 | ||||
| -rw-r--r-- | kernel/cgroup/cpuset.c | 13 |
2 files changed, 14 insertions, 4 deletions
diff --git a/kernel/cgroup/cpuset-internal.h b/kernel/cgroup/cpuset-internal.h index fd7d19842ded..bb4e692bea30 100644 --- a/kernel/cgroup/cpuset-internal.h +++ b/kernel/cgroup/cpuset-internal.h @@ -168,6 +168,11 @@ struct cpuset { int nr_deadline_tasks; int nr_migrate_dl_tasks; u64 sum_migrate_dl_bw; + /* + * CPU used for temporary DL bandwidth allocation during attach; + * -1 if no DL bandwidth was allocated in the current attach. + */ + int dl_bw_cpu; /* Invalid partition error code, not lock protected */ enum prs_errcode prs_err; diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 1335e437098e..e3a081a07c6d 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -288,6 +288,7 @@ struct cpuset top_cpuset = { .flags = BIT(CS_CPU_EXCLUSIVE) | BIT(CS_MEM_EXCLUSIVE) | BIT(CS_SCHED_LOAD_BALANCE), .partition_root_state = PRS_ROOT, + .dl_bw_cpu = -1, }; /** @@ -579,6 +580,8 @@ static struct cpuset *dup_or_alloc_cpuset(struct cpuset *cs) if (!trial) return NULL; + trial->dl_bw_cpu = -1; + /* Setup cpumask pointer array */ cpumask_var_t *pmask[4] = { &trial->cpus_allowed, @@ -2980,6 +2983,7 @@ static void reset_migrate_dl_data(struct cpuset *cs) { cs->nr_migrate_dl_tasks = 0; cs->sum_migrate_dl_bw = 0; + cs->dl_bw_cpu = -1; } /* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */ @@ -3056,6 +3060,8 @@ static int cpuset_can_attach(struct cgroup_taskset *tset) reset_migrate_dl_data(cs); goto out_unlock; } + + cs->dl_bw_cpu = cpu; } out_success: @@ -3080,12 +3086,11 @@ static void cpuset_cancel_attach(struct cgroup_taskset *tset) mutex_lock(&cpuset_mutex); dec_attach_in_progress_locked(cs); - if (cs->nr_migrate_dl_tasks) { - int cpu = cpumask_any(cs->effective_cpus); + if (cs->dl_bw_cpu >= 0) + dl_bw_free(cs->dl_bw_cpu, cs->sum_migrate_dl_bw); - dl_bw_free(cpu, cs->sum_migrate_dl_bw); + if (cs->nr_migrate_dl_tasks) reset_migrate_dl_data(cs); - } mutex_unlock(&cpuset_mutex); } |