lockdep_ass...d_lock_sched(9)

okay so bestie, buckle up: this is lockdep_ass...d_lock_sched(9) from the Kernel API Manual, and it’s giving “tiny helper, very serious lock-check energy.” 🫶

🎀 NAME 🎀

lockdep_assert_in_rcu_read_lock_sched — WARN if not protected by rcu_read_lock_sched(). That’s the whole vibe: it’s the lockdep check that side-eyes your code when the right RCU read lock isn’t held. 😭

✨ SYNOPSIS ✨

lockdep_assert_in_rcu_read_lock_sched

no args, no drama, just the function name. 💅

💅 DESCRIPTION 💅

Splats if lockdep is enabled and there is no rcu_read_lock_sched in effect. That’s it. That’s the tweet. 💀

Important caveat, bestie: preempt_disable and friends do not suffice here. Nope, not even close. Instead, an actual rcu_read_lock_sched is required. So don’t try to fake it with the preempt crew — lockdep wants the real thing. 👑

🌈 SEE ALSO 🌈

Kernel file ./include/linux/rcupdate.h — and the whole RCU friend group is here too. iykyk:

• same_state_synchronize_rcu(9)
• cond_resched_tasks_rcu_qs(9)
• rcu_softirq_qs_periodic(9)
• RCU_LOCKDEP_WARN(9)
• lockdep_assert_in_rcu_read_lock(9)
• lockdep_assert_in_rcu_read_lock_bh(9)
• lockdep_assert_in_rcu_reader(9)
• unrcu_pointer(9)
• RCU_INITIALIZER(9)
• rcu_assign_pointer(9)
• rcu_replace_pointer(9)
• rcu_access_pointer(9)
• rcu_dereference_check(9)
• rcu_dereference_bh_check(9)
• rcu_dereference_sched_check(9)
• rcu_dereference_all_check(9)
• rcu_dereference_protected(9)
• rcu_dereference(9)
• rcu_dereference_bh(9)
• rcu_dereference_sched(9)
• rcu_dereference_all(9)
• rcu_pointer_handoff(9)
• rcu_read_lock(9)
• rcu_read_unlock(9)
• rcu_read_lock_bh(9)
• rcu_read_unlock_bh(9)
• rcu_read_lock_sched(9)
• rcu_read_unlock_sched(9)
• RCU_INIT_POINTER(9)
• RCU_POINTER_INITIALIZER(9)
• kfree_rcu(9)
• kfree_rcu_mightsleep(9)
• kfree_rcu_nolock(9)
• rcu_head_init(9)
• rcu_head_after_call_rcu(9)

xoxo, your kernel bestie 💅 — source/version: ./include/linux, date: October 2026. Periodt. ✨