From: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org,
Steven Rostedt <rostedt@goodmis.org>,
linux-arm-kernel@lists.infradead.org,
Waiman Long <longman@redhat.com>, Will Deacon <will@kernel.org>,
Clark Williams <clrkwllms@kernel.org>
Subject: Re: [PATCH] arm64/entry: Don't disable preemption in debug_exception_enter() with RT kernel
Date: Wed, 20 May 2026 08:23:49 -0300 [thread overview]
Message-ID: <ag2ZxTA9YR-okKrU@redhat.com> (raw)
In-Reply-To: <20260520061920.XCqBHe0x@linutronix.de>
On Wed, May 20, 2026 at 08:19:20AM +0200, 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.
Sebastian, hardware breakpoint and watchpoint handlers still call
debug_exception_exit() and disable preemption on aarch64. That should
happen on v7.1-rc4 indeed. The suggestion was to mimic what x86_64 does
with notify_die() -> hw_breakpoint_exceptions_notify(). In ARM
hw_breakpoint_exceptions_notify() is a stub that always returns
NOTIFY_DONE.
Luis
> Sebastian
>
---end quoted text---
prev parent reply other threads:[~2026-05-20 11:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-19 22:25 [PATCH] arm64/entry: Don't disable preemption in debug_exception_enter() with RT kernel Waiman Long
2026-05-20 0:23 ` Luis Claudio R. Goncalves
2026-05-20 6:19 ` Sebastian Andrzej Siewior
2026-05-20 11:23 ` Luis Claudio R. Goncalves [this message]
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