[tip: sched/urgent] sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE()
From: tip-bot2 for Ingo Molnar
Date: Fri Aug 12 2022 - 05:59:11 EST
The following commit has been merged into the sched/urgent branch of tip:
Commit-ID: 09348d75a6ce60eec85c86dd0ab7babc4db3caf6
Gitweb: https://git.kernel.org/tip/09348d75a6ce60eec85c86dd0ab7babc4db3caf6
Author: Ingo Molnar <mingo@xxxxxxxxxx>
AuthorDate: Thu, 11 Aug 2022 08:54:52 +02:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Fri, 12 Aug 2022 11:25:10 +02:00
sched/all: Change all BUG_ON() instances in the scheduler to WARN_ON_ONCE()
There's no good reason to crash a user's system with a BUG_ON(),
chances are high that they'll never even see the crash message on
Xorg, and it won't make it into the syslog either.
By using a WARN_ON_ONCE() we at least give the user a chance to report
any bugs triggered here - instead of getting silent hangs.
None of these WARN_ON_ONCE()s are supposed to trigger, ever - so we ignore
cases where a NULL check is done via a BUG_ON() and we let a NULL
pointer through after a WARN_ON_ONCE().
There's one exception: WARN_ON_ONCE() arguments with side-effects,
such as locking - in this case we use the return value of the
WARN_ON_ONCE(), such as in:
- BUG_ON(!lock_task_sighand(p, &flags));
+ if (WARN_ON_ONCE(!lock_task_sighand(p, &flags)))
+ return;
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Link: https://lore.kernel.org/r/YvSsKcAXISmshtHo@xxxxxxxxx
---
kernel/sched/autogroup.c | 3 ++-
kernel/sched/core.c | 2 +-
kernel/sched/cpupri.c | 2 +-
kernel/sched/deadline.c | 26 +++++++++++++-------------
kernel/sched/fair.c | 10 +++++-----
kernel/sched/rt.c | 2 +-
kernel/sched/sched.h | 6 +++---
7 files changed, 26 insertions(+), 25 deletions(-)
diff --git a/kernel/sched/autogroup.c b/kernel/sched/autogroup.c
index 4ebaf97..991fc90 100644
--- a/kernel/sched/autogroup.c
+++ b/kernel/sched/autogroup.c
@@ -161,7 +161,8 @@ autogroup_move_group(struct task_struct *p, struct autogroup *ag)
struct task_struct *t;
unsigned long flags;
- BUG_ON(!lock_task_sighand(p, &flags));
+ if (WARN_ON_ONCE(!lock_task_sighand(p, &flags)))
+ return;
prev = p->signal->autogroup;
if (prev == ag) {
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ee28253..813687a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2328,7 +2328,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf,
rq = cpu_rq(new_cpu);
rq_lock(rq, rf);
- BUG_ON(task_cpu(p) != new_cpu);
+ WARN_ON_ONCE(task_cpu(p) != new_cpu);
activate_task(rq, p, 0);
check_preempt_curr(rq, p, 0);
diff --git a/kernel/sched/cpupri.c b/kernel/sched/cpupri.c
index fa9ce9d..a286e72 100644
--- a/kernel/sched/cpupri.c
+++ b/kernel/sched/cpupri.c
@@ -147,7 +147,7 @@ int cpupri_find_fitness(struct cpupri *cp, struct task_struct *p,
int task_pri = convert_prio(p->prio);
int idx, cpu;
- BUG_ON(task_pri >= CPUPRI_NR_PRIORITIES);
+ WARN_ON_ONCE(task_pri >= CPUPRI_NR_PRIORITIES);
for (idx = 0; idx < task_pri; idx++) {
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 0ab79d8..962b169 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -310,7 +310,7 @@ static void dl_change_utilization(struct task_struct *p, u64 new_bw)
{
struct rq *rq;
- BUG_ON(p->dl.flags & SCHED_FLAG_SUGOV);
+ WARN_ON_ONCE(p->dl.flags & SCHED_FLAG_SUGOV);
if (task_on_rq_queued(p))
return;
@@ -607,7 +607,7 @@ static void enqueue_pushable_dl_task(struct rq *rq, struct task_struct *p)
{
struct rb_node *leftmost;
- BUG_ON(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
+ WARN_ON_ONCE(!RB_EMPTY_NODE(&p->pushable_dl_tasks));
leftmost = rb_add_cached(&p->pushable_dl_tasks,
&rq->dl.pushable_dl_tasks_root,
@@ -684,7 +684,7 @@ static struct rq *dl_task_offline_migration(struct rq *rq, struct task_struct *p
* Failed to find any suitable CPU.
* The task will never come back!
*/
- BUG_ON(dl_bandwidth_enabled());
+ WARN_ON_ONCE(dl_bandwidth_enabled());
/*
* If admission control is disabled we
@@ -830,7 +830,7 @@ static void replenish_dl_entity(struct sched_dl_entity *dl_se)
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
struct rq *rq = rq_of_dl_rq(dl_rq);
- BUG_ON(pi_of(dl_se)->dl_runtime <= 0);
+ WARN_ON_ONCE(pi_of(dl_se)->dl_runtime <= 0);
/*
* This could be the case for a !-dl task that is boosted.
@@ -1616,7 +1616,7 @@ static void __enqueue_dl_entity(struct sched_dl_entity *dl_se)
{
struct dl_rq *dl_rq = dl_rq_of_se(dl_se);
- BUG_ON(!RB_EMPTY_NODE(&dl_se->rb_node));
+ WARN_ON_ONCE(!RB_EMPTY_NODE(&dl_se->rb_node));
rb_add_cached(&dl_se->rb_node, &dl_rq->root, __dl_less);
@@ -1640,7 +1640,7 @@ static void __dequeue_dl_entity(struct sched_dl_entity *dl_se)
static void
enqueue_dl_entity(struct sched_dl_entity *dl_se, int flags)
{
- BUG_ON(on_dl_rq(dl_se));
+ WARN_ON_ONCE(on_dl_rq(dl_se));
update_stats_enqueue_dl(dl_rq_of_se(dl_se), dl_se, flags);
@@ -2017,7 +2017,7 @@ static struct task_struct *pick_task_dl(struct rq *rq)
return NULL;
dl_se = pick_next_dl_entity(dl_rq);
- BUG_ON(!dl_se);
+ WARN_ON_ONCE(!dl_se);
p = dl_task_of(dl_se);
return p;
@@ -2277,12 +2277,12 @@ static struct task_struct *pick_next_pushable_dl_task(struct rq *rq)
p = __node_2_pdl(rb_first_cached(&rq->dl.pushable_dl_tasks_root));
- BUG_ON(rq->cpu != task_cpu(p));
- BUG_ON(task_current(rq, p));
- BUG_ON(p->nr_cpus_allowed <= 1);
+ WARN_ON_ONCE(rq->cpu != task_cpu(p));
+ WARN_ON_ONCE(task_current(rq, p));
+ WARN_ON_ONCE(p->nr_cpus_allowed <= 1);
- BUG_ON(!task_on_rq_queued(p));
- BUG_ON(!dl_task(p));
+ WARN_ON_ONCE(!task_on_rq_queued(p));
+ WARN_ON_ONCE(!dl_task(p));
return p;
}
@@ -2492,7 +2492,7 @@ static void set_cpus_allowed_dl(struct task_struct *p,
struct root_domain *src_rd;
struct rq *rq;
- BUG_ON(!dl_task(p));
+ WARN_ON_ONCE(!dl_task(p));
rq = task_rq(p);
src_rd = rq->rd;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 914096c..28f10dc 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2600,7 +2600,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags,
if (!join)
return;
- BUG_ON(irqs_disabled());
+ WARN_ON_ONCE(irqs_disabled());
double_lock_irq(&my_grp->lock, &grp->lock);
for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) {
@@ -7279,7 +7279,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;
find_matching_se(&se, &pse);
- BUG_ON(!pse);
+ WARN_ON_ONCE(!pse);
cse_is_idle = se_is_idle(se);
pse_is_idle = se_is_idle(pse);
@@ -8159,7 +8159,7 @@ static void attach_task(struct rq *rq, struct task_struct *p)
{
lockdep_assert_rq_held(rq);
- BUG_ON(task_rq(p) != rq);
+ WARN_ON_ONCE(task_rq(p) != rq);
activate_task(rq, p, ENQUEUE_NOCLOCK);
check_preempt_curr(rq, p, 0);
}
@@ -10134,7 +10134,7 @@ redo:
goto out_balanced;
}
- BUG_ON(busiest == env.dst_rq);
+ WARN_ON_ONCE(busiest == env.dst_rq);
schedstat_add(sd->lb_imbalance[idle], env.imbalance);
@@ -10430,7 +10430,7 @@ static int active_load_balance_cpu_stop(void *data)
* we need to fix it. Originally reported by
* Bjorn Helgaas on a 128-CPU setup.
*/
- BUG_ON(busiest_rq == target_rq);
+ WARN_ON_ONCE(busiest_rq == target_rq);
/* Search for an sd spanning us and the target CPU. */
rcu_read_lock();
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 55f39c8..2936fe5 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -843,7 +843,7 @@ static void __disable_runtime(struct rq *rq)
* We cannot be left wanting - that would mean some runtime
* leaked out of the system.
*/
- BUG_ON(want);
+ WARN_ON_ONCE(want);
balanced:
/*
* Disable all the borrow logic by pretending we have inf
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index e26688d..7a44dce 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2709,8 +2709,8 @@ static inline void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
- BUG_ON(!irqs_disabled());
- BUG_ON(rq1 != rq2);
+ WARN_ON_ONCE(!irqs_disabled());
+ WARN_ON_ONCE(rq1 != rq2);
raw_spin_rq_lock(rq1);
__acquire(rq2->lock); /* Fake it out ;) */
double_rq_clock_clear_update(rq1, rq2);
@@ -2726,7 +2726,7 @@ static inline void double_rq_unlock(struct rq *rq1, struct rq *rq2)
__releases(rq1->lock)
__releases(rq2->lock)
{
- BUG_ON(rq1 != rq2);
+ WARN_ON_ONCE(rq1 != rq2);
raw_spin_rq_unlock(rq1);
__release(rq2->lock);
}