sched/fair: Use RCU accessors consistently for ->numa_group
The old code used RCU annotations and accessors inconsistently for
->numa_group, which can lead to use-after-frees and NULL dereferences.
Let all accesses to ->numa_group use proper RCU helpers to prevent such
issues.
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Fixes: 8c8a743c50 ("sched/numa: Use {cpu, pid} to create task groups for shared faults")
Link: https://lkml.kernel.org/r/20190716152047.14424-3-jannh@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Jann Horn
Ingo Molnar
Родитель
16d51a590a
Коммит
cb361d8cde
|
|
@ -1092,7 +1092,15 @@ struct task_struct {
|
|||
u64 last_sum_exec_runtime;
|
||||
struct callback_head numa_work;
|
||||
|
||||
struct numa_group *numa_group;
|
||||
/*
|
||||
* This pointer is only modified for current in syscall and
|
||||
* pagefault context (and for tasks being destroyed), so it can be read
|
||||
* from any of the following contexts:
|
||||
* - RCU read-side critical section
|
||||
* - current->numa_group from everywhere
|
||||
* - task's runqueue locked, task not running
|
||||
*/
|
||||
struct numa_group __rcu *numa_group;
|
||||
|
||||
/*
|
||||
* numa_faults is an array split into four regions:
|
||||
|
|
|
|||
|
|
@ -1086,6 +1086,21 @@ struct numa_group {
|
|||
unsigned long faults[0];
|
||||
};
|
||||
|
||||
/*
|
||||
* For functions that can be called in multiple contexts that permit reading
|
||||
* ->numa_group (see struct task_struct for locking rules).
|
||||
*/
|
||||
static struct numa_group *deref_task_numa_group(struct task_struct *p)
|
||||
{
|
||||
return rcu_dereference_check(p->numa_group, p == current ||
|
||||
(lockdep_is_held(&task_rq(p)->lock) && !READ_ONCE(p->on_cpu)));
|
||||
}
|
||||
|
||||
static struct numa_group *deref_curr_numa_group(struct task_struct *p)
|
||||
{
|
||||
return rcu_dereference_protected(p->numa_group, p == current);
|
||||
}
|
||||
|
||||
static inline unsigned long group_faults_priv(struct numa_group *ng);
|
||||
static inline unsigned long group_faults_shared(struct numa_group *ng);
|
||||
|
||||
|
|
@ -1129,10 +1144,12 @@ static unsigned int task_scan_start(struct task_struct *p)
|
|||
{
|
||||
unsigned long smin = task_scan_min(p);
|
||||
unsigned long period = smin;
|
||||
struct numa_group *ng;
|
||||
|
||||
/* Scale the maximum scan period with the amount of shared memory. */
|
||||
if (p->numa_group) {
|
||||
struct numa_group *ng = p->numa_group;
|
||||
rcu_read_lock();
|
||||
ng = rcu_dereference(p->numa_group);
|
||||
if (ng) {
|
||||
unsigned long shared = group_faults_shared(ng);
|
||||
unsigned long private = group_faults_priv(ng);
|
||||
|
||||
|
|
@ -1140,6 +1157,7 @@ static unsigned int task_scan_start(struct task_struct *p)
|
|||
period *= shared + 1;
|
||||
period /= private + shared + 1;
|
||||
}
|
||||
rcu_read_unlock();
|
||||
|
||||
return max(smin, period);
|
||||
}
|
||||
|
|
@ -1148,13 +1166,14 @@ static unsigned int task_scan_max(struct task_struct *p)
|
|||
{
|
||||
unsigned long smin = task_scan_min(p);
|
||||
unsigned long smax;
|
||||
struct numa_group *ng;
|
||||
|
||||
/* Watch for min being lower than max due to floor calculations */
|
||||
smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p);
|
||||
|
||||
/* Scale the maximum scan period with the amount of shared memory. */
|
||||
if (p->numa_group) {
|
||||
struct numa_group *ng = p->numa_group;
|
||||
ng = deref_curr_numa_group(p);
|
||||
if (ng) {
|
||||
unsigned long shared = group_faults_shared(ng);
|
||||
unsigned long private = group_faults_priv(ng);
|
||||
unsigned long period = smax;
|
||||
|
|
@ -1186,7 +1205,7 @@ void init_numa_balancing(unsigned long clone_flags, struct task_struct *p)
|
|||
p->numa_scan_period = sysctl_numa_balancing_scan_delay;
|
||||
p->numa_work.next = &p->numa_work;
|
||||
p->numa_faults = NULL;
|
||||
p->numa_group = NULL;
|
||||
RCU_INIT_POINTER(p->numa_group, NULL);
|
||||
p->last_task_numa_placement = 0;
|
||||
p->last_sum_exec_runtime = 0;
|
||||
|
||||
|
|
@ -1233,7 +1252,16 @@ static void account_numa_dequeue(struct rq *rq, struct task_struct *p)
|
|||
|
||||
pid_t task_numa_group_id(struct task_struct *p)
|
||||
{
|
||||
return p->numa_group ? p->numa_group->gid : 0;
|
||||
struct numa_group *ng;
|
||||
pid_t gid = 0;
|
||||
|
||||
rcu_read_lock();
|
||||
ng = rcu_dereference(p->numa_group);
|
||||
if (ng)
|
||||
gid = ng->gid;
|
||||
rcu_read_unlock();
|
||||
|
||||
return gid;
|
||||
}
|
||||
|
||||
/*
|
||||
|
|
@ -1258,11 +1286,13 @@ static inline unsigned long task_faults(struct task_struct *p, int nid)
|
|||
|
||||
static inline unsigned long group_faults(struct task_struct *p, int nid)
|
||||
{
|
||||
if (!p->numa_group)
|
||||
struct numa_group *ng = deref_task_numa_group(p);
|
||||
|
||||
if (!ng)
|
||||
return 0;
|
||||
|
||||
return p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
|
||||
p->numa_group->faults[task_faults_idx(NUMA_MEM, nid, 1)];
|
||||
return ng->faults[task_faults_idx(NUMA_MEM, nid, 0)] +
|
||||
ng->faults[task_faults_idx(NUMA_MEM, nid, 1)];
|
||||
}
|
||||
|
||||
static inline unsigned long group_faults_cpu(struct numa_group *group, int nid)
|
||||
|
|
@ -1400,12 +1430,13 @@ static inline unsigned long task_weight(struct task_struct *p, int nid,
|
|||
static inline unsigned long group_weight(struct task_struct *p, int nid,
|
||||
int dist)
|
||||
{
|
||||
struct numa_group *ng = deref_task_numa_group(p);
|
||||
unsigned long faults, total_faults;
|
||||
|
||||
if (!p->numa_group)
|
||||
if (!ng)
|
||||
return 0;
|
||||
|
||||
total_faults = p->numa_group->total_faults;
|
||||
total_faults = ng->total_faults;
|
||||
|
||||
if (!total_faults)
|
||||
return 0;
|
||||
|
|
@ -1419,7 +1450,7 @@ static inline unsigned long group_weight(struct task_struct *p, int nid,
|
|||
bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
|
||||
int src_nid, int dst_cpu)
|
||||
{
|
||||
struct numa_group *ng = p->numa_group;
|
||||
struct numa_group *ng = deref_curr_numa_group(p);
|
||||
int dst_nid = cpu_to_node(dst_cpu);
|
||||
int last_cpupid, this_cpupid;
|
||||
|
||||
|
|
@ -1600,13 +1631,14 @@ static bool load_too_imbalanced(long src_load, long dst_load,
|
|||
static void task_numa_compare(struct task_numa_env *env,
|
||||
long taskimp, long groupimp, bool maymove)
|
||||
{
|
||||
struct numa_group *cur_ng, *p_ng = deref_curr_numa_group(env->p);
|
||||
struct rq *dst_rq = cpu_rq(env->dst_cpu);
|
||||
long imp = p_ng ? groupimp : taskimp;
|
||||
struct task_struct *cur;
|
||||
long src_load, dst_load;
|
||||
long load;
|
||||
long imp = env->p->numa_group ? groupimp : taskimp;
|
||||
long moveimp = imp;
|
||||
int dist = env->dist;
|
||||
long moveimp = imp;
|
||||
long load;
|
||||
|
||||
if (READ_ONCE(dst_rq->numa_migrate_on))
|
||||
return;
|
||||
|
|
@ -1645,21 +1677,22 @@ static void task_numa_compare(struct task_numa_env *env,
|
|||
* If dst and source tasks are in the same NUMA group, or not
|
||||
* in any group then look only at task weights.
|
||||
*/
|
||||
if (cur->numa_group == env->p->numa_group) {
|
||||
cur_ng = rcu_dereference(cur->numa_group);
|
||||
if (cur_ng == p_ng) {
|
||||
imp = taskimp + task_weight(cur, env->src_nid, dist) -
|
||||
task_weight(cur, env->dst_nid, dist);
|
||||
/*
|
||||
* Add some hysteresis to prevent swapping the
|
||||
* tasks within a group over tiny differences.
|
||||
*/
|
||||
if (cur->numa_group)
|
||||
if (cur_ng)
|
||||
imp -= imp / 16;
|
||||
} else {
|
||||
/*
|
||||
* Compare the group weights. If a task is all by itself
|
||||
* (not part of a group), use the task weight instead.
|
||||
*/
|
||||
if (cur->numa_group && env->p->numa_group)
|
||||
if (cur_ng && p_ng)
|
||||
imp += group_weight(cur, env->src_nid, dist) -
|
||||
group_weight(cur, env->dst_nid, dist);
|
||||
else
|
||||
|
|
@ -1757,11 +1790,12 @@ static int task_numa_migrate(struct task_struct *p)
|
|||
.best_imp = 0,
|
||||
.best_cpu = -1,
|
||||
};
|
||||
struct sched_domain *sd;
|
||||
struct rq *best_rq;
|
||||
unsigned long taskweight, groupweight;
|
||||
int nid, ret, dist;
|
||||
struct sched_domain *sd;
|
||||
long taskimp, groupimp;
|
||||
struct numa_group *ng;
|
||||
struct rq *best_rq;
|
||||
int nid, ret, dist;
|
||||
|
||||
/*
|
||||
* Pick the lowest SD_NUMA domain, as that would have the smallest
|
||||
|
|
@ -1807,7 +1841,8 @@ static int task_numa_migrate(struct task_struct *p)
|
|||
* multiple NUMA nodes; in order to better consolidate the group,
|
||||
* we need to check other locations.
|
||||
*/
|
||||
if (env.best_cpu == -1 || (p->numa_group && p->numa_group->active_nodes > 1)) {
|
||||
ng = deref_curr_numa_group(p);
|
||||
if (env.best_cpu == -1 || (ng && ng->active_nodes > 1)) {
|
||||
for_each_online_node(nid) {
|
||||
if (nid == env.src_nid || nid == p->numa_preferred_nid)
|
||||
continue;
|
||||
|
|
@ -1840,7 +1875,7 @@ static int task_numa_migrate(struct task_struct *p)
|
|||
* A task that migrated to a second choice node will be better off
|
||||
* trying for a better one later. Do not set the preferred node here.
|
||||
*/
|
||||
if (p->numa_group) {
|
||||
if (ng) {
|
||||
if (env.best_cpu == -1)
|
||||
nid = env.src_nid;
|
||||
else
|
||||
|
|
@ -2135,6 +2170,7 @@ static void task_numa_placement(struct task_struct *p)
|
|||
unsigned long total_faults;
|
||||
u64 runtime, period;
|
||||
spinlock_t *group_lock = NULL;
|
||||
struct numa_group *ng;
|
||||
|
||||
/*
|
||||
* The p->mm->numa_scan_seq field gets updated without
|
||||
|
|
@ -2152,8 +2188,9 @@ static void task_numa_placement(struct task_struct *p)
|
|||
runtime = numa_get_avg_runtime(p, &period);
|
||||
|
||||
/* If the task is part of a group prevent parallel updates to group stats */
|
||||
if (p->numa_group) {
|
||||
group_lock = &p->numa_group->lock;
|
||||
ng = deref_curr_numa_group(p);
|
||||
if (ng) {
|
||||
group_lock = &ng->lock;
|
||||
spin_lock_irq(group_lock);
|
||||
}
|
||||
|
||||
|
|
@ -2194,7 +2231,7 @@ static void task_numa_placement(struct task_struct *p)
|
|||
p->numa_faults[cpu_idx] += f_diff;
|
||||
faults += p->numa_faults[mem_idx];
|
||||
p->total_numa_faults += diff;
|
||||
if (p->numa_group) {
|
||||
if (ng) {
|
||||
/*
|
||||
* safe because we can only change our own group
|
||||
*
|
||||
|
|
@ -2202,14 +2239,14 @@ static void task_numa_placement(struct task_struct *p)
|
|||
* nid and priv in a specific region because it
|
||||
* is at the beginning of the numa_faults array.
|
||||
*/
|
||||
p->numa_group->faults[mem_idx] += diff;
|
||||
p->numa_group->faults_cpu[mem_idx] += f_diff;
|
||||
p->numa_group->total_faults += diff;
|
||||
group_faults += p->numa_group->faults[mem_idx];
|
||||
ng->faults[mem_idx] += diff;
|
||||
ng->faults_cpu[mem_idx] += f_diff;
|
||||
ng->total_faults += diff;
|
||||
group_faults += ng->faults[mem_idx];
|
||||
}
|
||||
}
|
||||
|
||||
if (!p->numa_group) {
|
||||
if (!ng) {
|
||||
if (faults > max_faults) {
|
||||
max_faults = faults;
|
||||
max_nid = nid;
|
||||
|
|
@ -2220,8 +2257,8 @@ static void task_numa_placement(struct task_struct *p)
|
|||
}
|
||||
}
|
||||
|
||||
if (p->numa_group) {
|
||||
numa_group_count_active_nodes(p->numa_group);
|
||||
if (ng) {
|
||||
numa_group_count_active_nodes(ng);
|
||||
spin_unlock_irq(group_lock);
|
||||
max_nid = preferred_group_nid(p, max_nid);
|
||||
}
|
||||
|
|
@ -2255,7 +2292,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
|
|||
int cpu = cpupid_to_cpu(cpupid);
|
||||
int i;
|
||||
|
||||
if (unlikely(!p->numa_group)) {
|
||||
if (unlikely(!deref_curr_numa_group(p))) {
|
||||
unsigned int size = sizeof(struct numa_group) +
|
||||
4*nr_node_ids*sizeof(unsigned long);
|
||||
|
||||
|
|
@ -2291,7 +2328,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
|
|||
if (!grp)
|
||||
goto no_join;
|
||||
|
||||
my_grp = p->numa_group;
|
||||
my_grp = deref_curr_numa_group(p);
|
||||
if (grp == my_grp)
|
||||
goto no_join;
|
||||
|
||||
|
|
@ -2362,7 +2399,8 @@ no_join:
|
|||
*/
|
||||
void task_numa_free(struct task_struct *p, bool final)
|
||||
{
|
||||
struct numa_group *grp = p->numa_group;
|
||||
/* safe: p either is current or is being freed by current */
|
||||
struct numa_group *grp = rcu_dereference_raw(p->numa_group);
|
||||
unsigned long *numa_faults = p->numa_faults;
|
||||
unsigned long flags;
|
||||
int i;
|
||||
|
|
@ -2442,7 +2480,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags)
|
|||
* actively using should be counted as local. This allows the
|
||||
* scan rate to slow down when a workload has settled down.
|
||||
*/
|
||||
ng = p->numa_group;
|
||||
ng = deref_curr_numa_group(p);
|
||||
if (!priv && !local && ng && ng->active_nodes > 1 &&
|
||||
numa_is_active_node(cpu_node, ng) &&
|
||||
numa_is_active_node(mem_node, ng))
|
||||
|
|
@ -10460,18 +10498,22 @@ void show_numa_stats(struct task_struct *p, struct seq_file *m)
|
|||
{
|
||||
int node;
|
||||
unsigned long tsf = 0, tpf = 0, gsf = 0, gpf = 0;
|
||||
struct numa_group *ng;
|
||||
|
||||
rcu_read_lock();
|
||||
ng = rcu_dereference(p->numa_group);
|
||||
for_each_online_node(node) {
|
||||
if (p->numa_faults) {
|
||||
tsf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 0)];
|
||||
tpf = p->numa_faults[task_faults_idx(NUMA_MEM, node, 1)];
|
||||
}
|
||||
if (p->numa_group) {
|
||||
gsf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 0)],
|
||||
gpf = p->numa_group->faults[task_faults_idx(NUMA_MEM, node, 1)];
|
||||
if (ng) {
|
||||
gsf = ng->faults[task_faults_idx(NUMA_MEM, node, 0)],
|
||||
gpf = ng->faults[task_faults_idx(NUMA_MEM, node, 1)];
|
||||
}
|
||||
print_numa_stats(m, node, tsf, tpf, gsf, gpf);
|
||||
}
|
||||
rcu_read_unlock();
|
||||
}
|
||||
#endif /* CONFIG_NUMA_BALANCING */
|
||||
#endif /* CONFIG_SCHED_DEBUG */
|
||||
|
|
|
|||
Загрузка…
Ссылка в новой задаче