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Two fixes for debugobjects:

Browse source 
- Prevent that the allocation path wakes up kswapd. That's a long
     standing issue due to the GFP_ATOMIC allocation flag. As debug objects
     can be invoked from pretty much any context waking kswapd can end up
     in arbitrary lock chains versus the waitqueue lock.
 
   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool().
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Merge tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull debugobjects fixes from Thomas Gleixner:
 "Two fixes for debugobjects:

   - Prevent the allocation path from waking up kswapd.

     That's a long standing issue due to the GFP_ATOMIC allocation flag.
     As debug objects can be invoked from pretty much any context waking
     kswapd can end up in arbitrary lock chains versus the waitqueue
     lock

   - Correct the explicit lockdep wait-type violation in
     debug_object_fill_pool()"

* tag 'core-debugobjects-2023-05-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  debugobjects: Don't wake up kswapd from fill_pool()
  debugobjects,locking: Annotate debug_object_fill_pool() wait type violation
This commit is contained in:
Linus Torvalds 2023-05-28 07:15:33 -04:00
commit d8f14b84fe
4 changed files with 50 additions and 10 deletions
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28
kernel/locking/lockdep.c
View file

@ -2263,6 +2263,9 @@ static inline bool usage_match(struct lock_list *entry, void *mask)
static inline bool usage_skip(struct lock_list *entry, void *mask)
{
if (entry->class->lock_type == LD_LOCK_NORMAL)
return false;
/*
* Skip local_lock() for irq inversion detection.
*
@ -2289,14 +2292,16 @@ static inline bool usage_skip(struct lock_list *entry, void *mask)
* As a result, we will skip local_lock(), when we search for irq
* inversion bugs.
*/
if (entry->class->lock_type == LD_LOCK_PERCPU) {
if (DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
return false;
if (entry->class->lock_type == LD_LOCK_PERCPU &&
DEBUG_LOCKS_WARN_ON(entry->class->wait_type_inner < LD_WAIT_CONFIG))
return false;
return true;
}
/*
* Skip WAIT_OVERRIDE for irq inversion detection -- it's not actually
* a lock and only used to override the wait_type.
*/
return false;
return true;
}
/*
@ -4768,7 +4773,8 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next)
for (; depth < curr->lockdep_depth; depth++) {
struct held_lock *prev = curr->held_locks + depth;
u8 prev_inner = hlock_class(prev)->wait_type_inner;
struct lock_class *class = hlock_class(prev);
u8 prev_inner = class->wait_type_inner;
if (prev_inner) {
/*
@ -4778,6 +4784,14 @@ static int check_wait_context(struct task_struct *curr, struct held_lock *next)
* Also due to trylocks.
*/
curr_inner = min(curr_inner, prev_inner);
/*
* Allow override for annotations -- this is typically
* only valid/needed for code that only exists when
* CONFIG_PREEMPT_RT=n.
*/
if (unlikely(class->lock_type == LD_LOCK_WAIT_OVERRIDE))
curr_inner = prev_inner;
}
}