[PATCH] arm64/entry: Don't disable preemption in debug_exception_enter() with RT kernel

[Sebastian Andrzej Siewior]

On 2026-05-20 17:01:00 [-0400], Waiman Long wrote:
> 
> On 5/20/26 2:19 AM, Sebastian Andrzej Siewior wrote:
> > On 2026-05-19 18:25:24 [-0400], Waiman Long wrote:
> > > Commit d8bb6718c4db ("arm64: Make debug exception handlers visible from
> > > RCU") introduces debug_exception_enter() and debug_exception_exit()
> > > where preemption is explicitly disabled. With a PREEMPT_RT debug kernel,
> > > the following bug report can happen.
> > …
> > 
> > What kernel is this? I have backport (which is being tested) for v6.6
> > and v6.12, the patches are from v6.17-rc1.
> 
> The kernel backtrace is produced using the latest v7.1-rc4 kernel. There are
> a number of changes to the debug_exception_enter() and
> debug_exception_exit() functions over the years, but the preemption disable
> code remains since its introduction in v5.3.

Let me look at this again.

> BTW, what v6.17-rc1 patches are you talking about?

https://lore.kernel.org/all/20260528144825.850351-1-bigeasy@linutronix.de/

> -Longman

Sebastian