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cgroup: Fixes for v6.11-rc4

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Three patches addressing cpuset corner cases.
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Merge tag 'cgroup-for-6.11-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:
 "Three patches addressing cpuset corner cases"

* tag 'cgroup-for-6.11-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/cpuset: Eliminate unncessary sched domains rebuilds in hotplug
  cgroup/cpuset: Clear effective_xcpus on cpus_allowed clearing only if cpus.exclusive not set
  cgroup/cpuset: fix panic caused by partcmd_update
This commit is contained in:
Linus Torvalds 2024-08-24 10:39:18 +08:00
commit d2bafcf224
1 changed files with 21 additions and 17 deletions
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38
kernel/cgroup/cpuset.c
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@ -232,6 +232,13 @@ static cpumask_var_t isolated_cpus;
/* List of remote partition root children */
static struct list_head remote_children;
/*
* A flag to force sched domain rebuild at the end of an operation while
* inhibiting it in the intermediate stages when set. Currently it is only
* set in hotplug code.
*/
static bool force_sd_rebuild;
/*
* Partition root states:
*
@ -1475,7 +1482,7 @@ static void update_partition_sd_lb(struct cpuset *cs, int old_prs)
clear_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
}
if (rebuild_domains)
if (rebuild_domains && !force_sd_rebuild)
rebuild_sched_domains_locked();
}
@ -1833,7 +1840,7 @@ static void remote_partition_check(struct cpuset *cs, struct cpumask *newmask,
remote_partition_disable(child, tmp);
disable_cnt++;
}
if (disable_cnt)
if (disable_cnt && !force_sd_rebuild)
rebuild_sched_domains_locked();
}
@ -1991,6 +1998,8 @@ static int update_parent_effective_cpumask(struct cpuset *cs, int cmd,
part_error = PERR_CPUSEMPTY;
goto write_error;
}
/* Check newmask again, whether cpus are available for parent/cs */
nocpu |= tasks_nocpu_error(parent, cs, newmask);
/*
* partcmd_update with newmask:
@ -2440,7 +2449,8 @@ static void update_cpumasks_hier(struct cpuset *cs, struct tmpmasks *tmp,
}
rcu_read_unlock();
if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD))
if (need_rebuild_sched_domains && !(flags & HIER_NO_SD_REBUILD) &&
!force_sd_rebuild)
rebuild_sched_domains_locked();
}
@ -2523,7 +2533,8 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
*/
if (!*buf) {
cpumask_clear(trialcs->cpus_allowed);
cpumask_clear(trialcs->effective_xcpus);
if (cpumask_empty(trialcs->exclusive_cpus))
cpumask_clear(trialcs->effective_xcpus);
} else {
retval = cpulist_parse(buf, trialcs->cpus_allowed);
if (retval < 0)
@ -3101,7 +3112,8 @@ static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
cs->flags = trialcs->flags;
spin_unlock_irq(&callback_lock);
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed &&
!force_sd_rebuild)
rebuild_sched_domains_locked();
if (spread_flag_changed)
@ -4498,11 +4510,9 @@ hotplug_update_tasks(struct cpuset *cs,
update_tasks_nodemask(cs);
}
static bool force_rebuild;
void cpuset_force_rebuild(void)
{
force_rebuild = true;
force_sd_rebuild = true;
}
/**
@ -4650,15 +4660,9 @@ static void cpuset_handle_hotplug(void)
!cpumask_empty(subpartitions_cpus);
mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
/*
* In the rare case that hotplug removes all the cpus in
* subpartitions_cpus, we assumed that cpus are updated.
*/
if (!cpus_updated && !cpumask_empty(subpartitions_cpus))
cpus_updated = true;
/* For v1, synchronize cpus_allowed to cpu_active_mask */
if (cpus_updated) {
cpuset_force_rebuild();
spin_lock_irq(&callback_lock);
if (!on_dfl)
cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
@ -4714,8 +4718,8 @@ static void cpuset_handle_hotplug(void)
}
/* rebuild sched domains if cpus_allowed has changed */
if (cpus_updated || force_rebuild) {
force_rebuild = false;
if (force_sd_rebuild) {
force_sd_rebuild = false;
rebuild_sched_domains_cpuslocked();
}