On Thu, 28 Nov 2024 at 02:25, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > On Fri, 22 Nov 2024 16:39:47 +0100 Marco Elver <elver@xxxxxxxxxx> wrote: > > > Per documentation, stack_depot_save_flags() was meant to be usable from > > NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset. However, it still > > would try to take the pool_lock in an attempt to save a stack trace in > > the current pool (if space is available). > > > > This could result in deadlock if an NMI is handled while pool_lock is > > already held. To avoid deadlock, only try to take the lock in NMI > > context and give up if unsuccessful. > > Is it possible to trigger this deadlock in current kernels, or is this > a might-happen-in-the-future thing? I can't find evidence this happens right now (at least with the quick test I just ran), so it's more of a might happen if use of this API broadens. Thanks, -- Marco
