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debugobjects: Do not fill_pool() if pi_blocked_on

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On RT enabled kernels, fill_pool() ends up calling rtlock_lock(), which
asserts if current::pi_blocked_on is set, because a task can obviously only
block on one lock as otherwise the priority inheritenace chain gets
corrupted.

Prevent this by expanding the conditional to take current::pi_blocked_on
into account.

Fixes: 4bedcc2846 ("debugobjects: Make them PREEMPT_RT aware")
Reported-by: syzbot+b8ca586b9fc235f0c0df@syzkaller.appspotmail.com
Signed-off-by: Helen Koike <koike@igalia.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260511215359.3351259-1-koike@igalia.com
Closes: https://syzkaller.appspot.com/bug?extid=b8ca586b9fc235f0c0df
This commit is contained in:
Helen Koike 2026-05-11 18:53:05 -03:00 committed by Thomas Gleixner
parent 5200f5f493
commit 5f41161059
1 changed files with 14 additions and 4 deletions
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18
lib/debugobjects.c
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@ -711,6 +711,15 @@ static struct debug_obj *lookup_object_or_alloc(void *addr, struct debug_bucket
return NULL;
}
static inline bool debug_objects_is_pi_blocked_on(void)
{
#ifdef CONFIG_RT_MUTEXES
return current->pi_blocked_on != NULL;
#else
return false;
#endif
}
static void debug_objects_fill_pool(void)
{
if (!static_branch_likely(&obj_cache_enabled))
@ -727,11 +736,12 @@ static void debug_objects_fill_pool(void)
/*
* On RT enabled kernels the pool refill must happen in preemptible
* context -- for !RT kernels we rely on the fact that spinlock_t and
* raw_spinlock_t are basically the same type and this lock-type
* inversion works just fine.
* context and not enqueued on an rt_mutex -- for !RT kernels we rely
* on the fact that spinlock_t and raw_spinlock_t are basically the
* same type and this lock-type inversion works just fine.
*/
if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible() || system_state < SYSTEM_SCHEDULING) {
if (!IS_ENABLED(CONFIG_PREEMPT_RT) || system_state < SYSTEM_SCHEDULING ||
(preemptible() && !debug_objects_is_pi_blocked_on())) {
/*
* Annotate away the spinlock_t inside raw_spinlock_t warning
* by temporarily raising the wait-type to LD_WAIT_CONFIG, matching