lockdep_asse...read_lock_bh(9)

🌸 lockdep_asse...read_lock_bh — the Kernel API Manual, bestie edition 🌸

okay so this one lives in the Kernel API Manual and honestly the vibe is: "did you actually hold the lock or are you lying to me?" 💅

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✨ NAME ✨

lockdep_assert_in_rcu_read_lock_bh — literally goes WARN if you're not protected by rcu_read_lock_bh(). that's it. that's the whole job 🫶

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🦋 SYNOPSIS 🦋

lockdep_assert_in_rcu_read_lock_bh

no args, no options, no drama. she's a function and she shows up exactly like that 👑

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💖 DESCRIPTION 💖

So here's the tea ☕ — this thing splats if lockdep is enabled and there is no rcu_read_lock_bh in effect. Like, full-on screaming into the kernel log. not subtle. not cute. but necessary, ngl 😭

And here's the part people get wrong every single time, so pay attention bestie 👀: local_bh_disable and friends do not suffice here. nope. not even a little. an actual rcu_read_lock_bh is required.

so if you're sitting there like "but I disabled bh tho??" — ma'am. that is not the same thing. the check wants the real one. periodt 💀

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👑 SEE ALSO 👑

the whole extended friend group, in the order they were introduced 🎀

• 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_sched(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)

also shoutout to where she actually lives: the kernel file ./include/linux/rcupdate.h — that's her address, don't lose it 🏡

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and that's the whole page, bestie ✨ this icon was brought to you by the good people at ./include/linux, dated October 2026, and filed under lockdep_asse...read_lock_bh(9) in the Kernel API Manual. slay, stay locked, and please use the actual rcu_read_lock_bh 💜🎀