Subject: Re: [PATCH 0/3] powerpc: fix preempt_count imbalances in perf and kexec paths

From: Aboorva Devarajan <[email-masked]>
Date: Wed, 03 Jun 2026 11:46:52 +0530

On Mon, 2026-05-18 at 13:38 +0530, Shrikanth Hegde wrote:
> Hi Aboorva,
> 
> On 5/18/26 10:38 AM, Aboorva Devarajan wrote:
> > Hi all,
> > 
> > This patch series fixes some minor preempt_count bookkeeping issues in
> > arch/powerpc/ found during a preemption leak audit prompted by the
> > lazy/full preemption model changes. These are get_cpu/put_cpu and
> > get_cpu_var/put_cpu_var pairing errors that leave preempt_count
> > incorrectly elevated or underflowed.
> > 
> 
> Thanks for fixing some of these.
> 
> while we do this, Can you fix these mismatch in preempt disable/enable in
> below files as well.
> 
> 1. kernel/kprobes.c - kprobe_handler - Does disable, but doesn't enable in some return paths.
>     A definite leak.
> 
> 2. Maybe platforms/pseries/lpar.c and platforms/powernv/opal-tracepoints.c.
>     In __trace_hcall_entry/exit.  It maybe a very corner case,
>     I don't see a big concern there. But it may be remotely possible.
>     Need to evaluate whether it should be fixed or not.

Thanks for the pointers. I'll go through these and get back.

Regards,
Aboorva