Re: [PATCH v2 2/4] fprobe: make fprobe_kprobe_handler recursion free

Ze Gao
2023-05-16T09:48:12Z

Precisely, these that are called within kprobe_busy_{begin, end},
which the previous patch does not resolve.
I will refine the commit message to make it clear.

FYI, details can checked out here:
Link: https://lore.kernel.org/linux-trace-kernel/20230516132516.c902edcf21028874a74fb868@kernel.org/

Regards,
Ze

On Tue, May 16, 2023 at 5:18 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Tue, May 16, 2023 at 03:18:28PM +0800, Ze Gao wrote:
> > Current implementation calls kprobe related functions before doing
> > ftrace recursion check in fprobe_kprobe_handler, which opens door
> > to kernel crash due to stack recursion if preempt_count_{add, sub}
> > is traceable.
>
> Which preempt_count*() are you referring to? The ones you just made
> _notrace in the previous patch?