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McKenney wrote: > On Wed, Jul 29, 2026 at 11:45:40AM +0200, Philipp Stanner wrote: >> rcu_barrier() is a frequently used C function which is always safe to be >> called. > > Just checking... Here "always safe" means only from task level, with BH, > preemption, and interrupts all enabled, correct? > > In contrast, if you do this: > > preempt_disable(); > rcu_barrier(); > preempt_enable(); > > the results won't be safe. This is same for all sleepable functions. In order to avoid having to mark = all sleeping function unsafe, we've decided that sleeping from non-preemptable context is "safe", but is a bug regardless. Best, Gary