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. Add a new statically allocated cs_tmp_cpus cpumask (protected by cpuset_mutex) for internal use so that all the three temporary cpumasks can be freely used.

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().

Also add a init_tmpmasks() helper to handle initialization of the tmpmasks structure when cpumasks are too big to be statically allocated on stack.

Signed-off-by: Waiman Long longman@redhat.com --- kernel/cgroup/cpuset.c | 66 ++++++++++++++++++++++++------------------ 1 file changed, 38 insertions(+), 28 deletions(-)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 12a0b583aca4..8604c919e1e4 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -208,6 +208,8 @@ struct cpuset { struct cgroup_file partition_file; };

+static cpumask_var_t cs_tmp_cpus; /* Temp cpumask for partition */ + /* * Partition root states: * @@ -668,6 +670,24 @@ static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp) } }

+/* + * init_tmpmasks - Initialize the cpumasks in tmpmasks with the given ones + */ +#ifdef CONFIG_CPUMASK_OFFSTACK +static inline void +init_tmpmasks(struct tmpmasks *tmp, struct cpumask *new_cpus, + struct cpumask *addmask, struct cpumask *delmask) +{ + tmp->new_cpus = new_cpus; + tmp->addmask = addmask; + tmp->delmask = delmask; +} +#else +static inline void +init_tmpmasks(struct tmpmasks *tmp, struct cpumask *new_cpus, + struct cpumask *addmask, struct cpumask *delmask) { } +#endif + /** * alloc_trial_cpuset - allocate a trial cpuset * @cs: the cpuset that the trial cpuset duplicates @@ -1300,6 +1320,8 @@ 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 @@ -1463,7 +1485,7 @@ 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; @@ -1583,8 +1605,11 @@ 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 @@ -1839,18 +1864,13 @@ 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. + * to allocated cpumasks & save the newmask into cs_tmp_cpus. */ - tmp.addmask = trialcs->subparts_cpus; - tmp.delmask = trialcs->effective_cpus; - tmp.new_cpus = NULL; -#endif + cpumask_copy(cs_tmp_cpus, trialcs->cpus_allowed); + init_tmpmasks(&tmp, trialcs->cpus_allowed, trialcs->subparts_cpus, + trialcs->effective_cpus);

retval = validate_change(cs, trialcs);

@@ -1870,7 +1890,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, parent = parent_cs(cs); cpuset_for_each_child(cp, css, parent) if (is_partition_valid(cp) && - cpumask_intersects(trialcs->cpus_allowed, cp->cpus_allowed)) { + cpumask_intersects(cs_tmp_cpus, cp->cpus_allowed)) { rcu_read_unlock(); update_parent_subparts_cpumask(cp, partcmd_invalidate, NULL, &tmp); rcu_read_lock(); @@ -1887,13 +1907,15 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs, NULL, &tmp); else update_parent_subparts_cpumask(cs, partcmd_update, - trialcs->cpus_allowed, &tmp); + cs_tmp_cpus, &tmp); }

+ /* Restore trialcs->cpus_allowed */ + cpumask_copy(trialcs->cpus_allowed, cs_tmp_cpus); compute_effective_cpumask(trialcs->effective_cpus, trialcs, parent_cs(cs)); spin_lock_irq(&callback_lock); - cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed); + cpumask_copy(cs->cpus_allowed, cs_tmp_cpus);

/* * Make sure that subparts_cpus, if not empty, is a subset of @@ -1914,11 +1936,6 @@ 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);

@@ -2343,13 +2360,11 @@ 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 @@ -2369,12 +2384,6 @@ 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 @@ -3500,6 +3509,7 @@ int __init cpuset_init(void) BUG_ON(!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL)); BUG_ON(!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL)); BUG_ON(!zalloc_cpumask_var(&top_cpuset.subparts_cpus, GFP_KERNEL)); + BUG_ON(!zalloc_cpumask_var(&cs_tmp_cpus, GFP_KERNEL));

cpumask_setall(top_cpuset.cpus_allowed); nodes_setall(top_cpuset.mems_allowed);