UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

sched: avoid false lockdep splat in put_task_struct() 

In put_task_struct(), a spin_lock is indirectly acquired under the kernel
stock. When running the kernel in real-time (RT) configuration, the
operation is dispatched to a preemptible context call to ensure
guaranteed preemption. However, if PROVE_RAW_LOCK_NESTING is enabled
and __put_task_struct() is called while holding a raw_spinlock, lockdep
incorrectly reports an "Invalid lock context" in the stock kernel.

This false splat occurs because lockdep is unaware of the different
route taken under RT. To address this issue, override the inner wait
type to prevent the false lockdep splat.

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230614122323.37957-3-wander@redhat.com
This commit is contained in:
Wander Lairson Costa 2023-06-14 09:23:22 -03:00 committed by Peter Zijlstra
parent d243b34459
commit 893cdaaa39
1 changed files with 14 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
include/linux/sched/task.h
View File

@ -125,6 +125,19 @@ static inline void put_task_struct(struct task_struct *t)
if (!refcount_dec_and_test(&t->usage))
return;
/*
* In !RT, it is always safe to call __put_task_struct().
* Under RT, we can only call it in preemptible context.
*/
if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible()) {
static DEFINE_WAIT_OVERRIDE_MAP(put_task_map, LD_WAIT_SLEEP);
lock_map_acquire_try(&put_task_map);
__put_task_struct(t);
lock_map_release(&put_task_map);
return;
}
/*
* under PREEMPT_RT, we can't call put_task_struct
* in atomic context because it will indirectly
@ -145,10 +158,7 @@ static inline void put_task_struct(struct task_struct *t)
* when it fails to fork a process. Therefore, there is no
* way it can conflict with put_task_struct().
*/
if (IS_ENABLED(CONFIG_PREEMPT_RT) && !preemptible())
call_rcu(&t->rcu, __put_task_struct_rcu_cb);
else
__put_task_struct(t);
call_rcu(&t->rcu, __put_task_struct_rcu_cb);
}
DEFINE_FREE(put_task, struct task_struct *, if (_T) put_task_struct(_T))