From 5f41161059fd0f1bbf18c90f3180e38cc45a14eb Mon Sep 17 00:00:00 2001 From: Helen Koike Date: Mon, 11 May 2026 18:53:05 -0300 Subject: [PATCH] debugobjects: Do not fill_pool() if pi_blocked_on 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: 4bedcc28469a ("debugobjects: Make them PREEMPT_RT aware") Reported-by: syzbot+b8ca586b9fc235f0c0df@syzkaller.appspotmail.com Signed-off-by: Helen Koike Signed-off-by: Thomas Gleixner Link: https://patch.msgid.link/20260511215359.3351259-1-koike@igalia.com Closes: https://syzkaller.appspot.com/bug?extid=b8ca586b9fc235f0c0df --- lib/debugobjects.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 12e2e42e6a31..772ddabcbe7d 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -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