Nicholas Piggin wrote:

On Fri Oct 21, 2022 at 3:28 AM AEST, Naveen N. Rao wrote:

quoted

arch_prepare_kprobe() is called from register_kprobe() via
prepare_kprobe(), or through register_aggr_kprobe(), both with the
kprobe_mutex held. Per the comment for get_kprobe():
  /*
   * This routine is called either:
   *	- under the 'kprobe_mutex' - during kprobe_[un]register().
   *				OR
   *	- with preemption disabled - from architecture specific code.
   */

That comment should read [un]register_kprobe(), right?

Ugh, yes!

quoted

As such, there is no need to disable preemption around the call to
get_kprobe(). Drop the same.

And prepare_kprobe() and register_aggr_kprobe() are both called with
kprobe_mutex held so you rely on the same protection. This seems to
fix a lost-resched bug with preempt kernels too.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

Thanks,
Naveen