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cgroup/cpuset: Improve temporary cpumasks handling

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The limitation that update_parent_subparts_cpumask() can only use
addmask & delmask in the given tmp cpumasks is fragile and may lead to
unexpected error.

Fix this problem by allocating/freeing a struct tmpmasks in
update_cpumask() to avoid reusing the cpumasks in trial_cs.

With this change, we can move the update_tasks_cpumask() for the
parent and update_sibling_cpumasks() for the sibling to inside
update_parent_subparts_cpumask().

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Waiman Long 2023-06-27 10:35:02 -04:00 committed by Tejun Heo
parent a86ce68078
commit 99fe36ba6f
1 changed files with 13 additions and 29 deletions
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42
kernel/cgroup/cpuset.c
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@ -1277,6 +1277,8 @@ enum subparts_cmd {
static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
int turning_on);
static void update_sibling_cpumasks(struct cpuset *parent, struct cpuset *cs,
struct tmpmasks *tmp);
/*
* Update partition exclusive flag
@ -1447,7 +1449,7 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
adding = cpumask_andnot(tmp->addmask, tmp->addmask,
parent->subparts_cpus);
/*
* Empty cpumask is not allewed
* Empty cpumask is not allowed
*/
if (cpumask_empty(newmask)) {
part_error = PERR_CPUSEMPTY;
@ -1567,8 +1569,11 @@ static int update_parent_subparts_cpumask(struct cpuset *cs, int cmd,
spin_unlock_irq(&callback_lock);
if (adding || deleting)
if (adding || deleting) {
update_tasks_cpumask(parent, tmp->addmask);
if (parent->child_ecpus_count)
update_sibling_cpumasks(parent, cs, tmp);
}
/*
* For partcmd_update without newmask, it is being called from
@ -1842,18 +1847,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
return 0;
#ifdef CONFIG_CPUMASK_OFFSTACK
/*
* Use the cpumasks in trialcs for tmpmasks when they are pointers
* to allocated cpumasks.
*
* Note that update_parent_subparts_cpumask() uses only addmask &
* delmask, but not new_cpus.
*/
tmp.addmask = trialcs->subparts_cpus;
tmp.delmask = trialcs->effective_cpus;
tmp.new_cpus = NULL;
#endif
if (alloc_cpumasks(NULL, &tmp))
return -ENOMEM;
retval = validate_change(cs, trialcs);
@ -1882,7 +1877,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
retval = 0;
}
if (retval < 0)
return retval;
goto out_free;
if (cs->partition_root_state) {
if (invalidate)
@ -1917,11 +1912,6 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
}
spin_unlock_irq(&callback_lock);
#ifdef CONFIG_CPUMASK_OFFSTACK
/* Now trialcs->cpus_allowed is available */
tmp.new_cpus = trialcs->cpus_allowed;
#endif
/* effective_cpus will be updated here */
update_cpumasks_hier(cs, &tmp, false);
@ -1938,6 +1928,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
/* Update CS_SCHED_LOAD_BALANCE and/or sched_domains */
update_partition_sd_lb(cs, old_prs);
}
out_free:
free_cpumasks(NULL, &tmp);
return 0;
}
@ -2346,13 +2338,11 @@ static int update_prstate(struct cpuset *cs, int new_prs)
err = update_parent_subparts_cpumask(cs, partcmd_enable,
NULL, &tmpmask);
if (err)
goto out;
} else if (old_prs && new_prs) {
/*
* A change in load balance state only, no change in cpumasks.
*/
goto out;
;
} else {
/*
* Switching back to member is always allowed even if it
@ -2372,12 +2362,6 @@ static int update_prstate(struct cpuset *cs, int new_prs)
spin_unlock_irq(&callback_lock);
}
}
update_tasks_cpumask(parent, tmpmask.new_cpus);
if (parent->child_ecpus_count)
update_sibling_cpumasks(parent, cs, &tmpmask);
out:
/*
* Make partition invalid & disable CS_CPU_EXCLUSIVE if an error