On Thu, Oct 31, 2024 at 08:55:09AM +0100, Sebastian Andrzej Siewior wrote: > On 2024-10-31 08:35:45 [+0100], Vlastimil Babka wrote: > > On 10/31/24 08:21, Sebastian Andrzej Siewior wrote: > > > On 2024-10-30 16:10:58 [-0700], Paul E. McKenney wrote: > > >> > > >> So I need to avoid calling kfree() within an smp_call_function() handler? > > > > > > Yes. No kmalloc()/ kfree() in IRQ context. > > > > However, isn't this the case that the rule is actually about hardirq context > > on RT, and most of these operations that are in IRQ context on !RT become > > the threaded interrupt context on RT, so they are actually fine? Or is smp > > call callback a hardirq context on RT and thus it really can't do those > > operations? > > interrupt handlers as of request_irq() are forced-threaded on RT so you > can do kmalloc()/ kfree() there. smp_call_function.*() on the other hand > are not threaded and invoked directly within the IRQ context. OK, thank you all for the explanation! I will fix using Boqun's suggestion of irq work, but avoiding the issue Boqun raises by invoking the irq-work handler from the smp_call_function() handler. It will be a few days before I get to this, so if there is a better way, please do not keep it a secret! Thanx, Paul
