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cpuset: add cpuset1_online_css helper for v1-specific operations

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This commit introduces the cpuset1_online_css helper to centralize
v1-specific handling during cpuset online. It performs operations such as
updating the CS_SPREAD_PAGE, CS_SPREAD_SLAB, and CGRP_CPUSET_CLONE_CHILDREN
flags, which are unique to the cpuset v1 control group interface.

The helper is now placed in cpuset-v1.c to maintain clear separation
between v1 and v2 logic.

Signed-off-by: Chen Ridong <chenridong@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Chen Ridong 2025-12-18 09:31:37 +00:00 committed by Tejun Heo
parent 14c11e1b2a
commit 56805c1bb1
3 changed files with 51 additions and 38 deletions
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2
kernel/cgroup/cpuset-internal.h
View File

@ -293,6 +293,7 @@ void cpuset1_hotplug_update_tasks(struct cpuset *cs,
struct cpumask *new_cpus, nodemask_t *new_mems,
bool cpus_updated, bool mems_updated);
int cpuset1_validate_change(struct cpuset *cur, struct cpuset *trial);
void cpuset1_online_css(struct cgroup_subsys_state *css);
#else
static inline void fmeter_init(struct fmeter *fmp) {}
static inline void cpuset1_update_task_spread_flags(struct cpuset *cs,
@ -303,6 +304,7 @@ static inline void cpuset1_hotplug_update_tasks(struct cpuset *cs,
bool cpus_updated, bool mems_updated) {}
static inline int cpuset1_validate_change(struct cpuset *cur,
struct cpuset *trial) { return 0; }
static inline void cpuset1_online_css(struct cgroup_subsys_state *css) {}
#endif /* CONFIG_CPUSETS_V1 */
#endif /* __CPUSET_INTERNAL_H */

48
kernel/cgroup/cpuset-v1.c
View File

@ -499,6 +499,54 @@ static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
return retval;
}
void cpuset1_online_css(struct cgroup_subsys_state *css)
{
struct cpuset *tmp_cs;
struct cgroup_subsys_state *pos_css;
struct cpuset *cs = css_cs(css);
struct cpuset *parent = parent_cs(cs);
lockdep_assert_cpus_held();
lockdep_assert_cpuset_lock_held();
if (is_spread_page(parent))
set_bit(CS_SPREAD_PAGE, &cs->flags);
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
return;
/*
* Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
* set. This flag handling is implemented in cgroup core for
* historical reasons - the flag may be specified during mount.
*
* Currently, if any sibling cpusets have exclusive cpus or mem, we
* refuse to clone the configuration - thereby refusing the task to
* be entered, and as a result refusing the sys_unshare() or
* clone() which initiated it. If this becomes a problem for some
* users who wish to allow that scenario, then this could be
* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
* (and likewise for mems) to the new cgroup.
*/
rcu_read_lock();
cpuset_for_each_child(tmp_cs, pos_css, parent) {
if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
rcu_read_unlock();
return;
}
}
rcu_read_unlock();
cpuset_callback_lock_irq();
cs->mems_allowed = parent->mems_allowed;
cs->effective_mems = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
cpuset_callback_unlock_irq();
}
/*
* for the common functions, 'private' gives the type of file
*/

39
kernel/cgroup/cpuset.c
View File

@ -3616,17 +3616,11 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
{
struct cpuset *cs = css_cs(css);
struct cpuset *parent = parent_cs(cs);
struct cpuset *tmp_cs;
struct cgroup_subsys_state *pos_css;
if (!parent)
return 0;
cpuset_full_lock();
if (is_spread_page(parent))
set_bit(CS_SPREAD_PAGE, &cs->flags);
if (is_spread_slab(parent))
set_bit(CS_SPREAD_SLAB, &cs->flags);
/*
* For v2, clear CS_SCHED_LOAD_BALANCE if parent is isolated
*/
@ -3641,39 +3635,8 @@ static int cpuset_css_online(struct cgroup_subsys_state *css)
cs->effective_mems = parent->effective_mems;
}
spin_unlock_irq(&callback_lock);
cpuset1_online_css(css);
if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
goto out_unlock;
/*
* Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
* set. This flag handling is implemented in cgroup core for
* historical reasons - the flag may be specified during mount.
*
* Currently, if any sibling cpusets have exclusive cpus or mem, we
* refuse to clone the configuration - thereby refusing the task to
* be entered, and as a result refusing the sys_unshare() or
* clone() which initiated it. If this becomes a problem for some
* users who wish to allow that scenario, then this could be
* changed to grant parent->cpus_allowed-sibling_cpus_exclusive
* (and likewise for mems) to the new cgroup.
*/
rcu_read_lock();
cpuset_for_each_child(tmp_cs, pos_css, parent) {
if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
rcu_read_unlock();
goto out_unlock;
}
}
rcu_read_unlock();
spin_lock_irq(&callback_lock);
cs->mems_allowed = parent->mems_allowed;
cs->effective_mems = parent->mems_allowed;
cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
spin_unlock_irq(&callback_lock);
out_unlock:
cpuset_full_unlock();
return 0;
}