From: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Waiman Long <longman@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Clark Williams <clrkwllms@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev,
Ada Couprie Diaz <ada.coupriediaz@arm.com>
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---
WARNING: multiple messages have this Message-ID (diff)
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---
next prev parent reply other threads:[~2026-05-20 11:23 UTC|newest]
Thread overview: 9+ 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]
2026-05-20 11:23 ` Luis Claudio R. Goncalves
2026-05-20 21:01 ` Waiman Long
2026-05-28 14:51 ` Sebastian Andrzej Siewior
2026-05-28 15:35 ` Sebastian Andrzej Siewior
2026-05-30 0:51 ` Luis Claudio R. Goncalves
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=ag2ZxTA9YR-okKrU@redhat.com \
--to=lgoncalv@redhat.com \
--cc=ada.coupriediaz@arm.com \
--cc=bigeasy@linutronix.de \
--cc=catalin.marinas@arm.com \
--cc=clrkwllms@kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rt-devel@lists.linux.dev \
--cc=longman@redhat.com \
--cc=mark.rutland@arm.com \
--cc=rostedt@goodmis.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.