From: Steven Rostedt <rostedt@goodmis.org>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: David Laight <david.laight.linux@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
mingo@redhat.com, will@kernel.org, boqun@kernel.org,
longman@redhat.com, mhiramat@kernel.org, mark.rutland@arm.com,
mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org,
linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] locking: add mutex_lock_nospin()
Date: Wed, 4 Mar 2026 22:00:19 -0500 [thread overview]
Message-ID: <20260304220019.3efa12ab@robin> (raw)
In-Reply-To: <CALOAHbBA643_QOsnTmrfjKE71hSa+v1cToiELvGk+vjtcgJsxg@mail.gmail.com>
On Thu, 5 Mar 2026 10:33:00 +0800
Yafang Shao <laoar.shao@gmail.com> wrote:
> Other tools may also read available_filter_functions, requiring each
> one to be patched individually to avoid this flaw—a clearly
> impractical solution.
What exactly is the issue? If a task does a while 1 in user space, it
wouldn't be much different. With PREEMPT_LAZY the most a task will spin
in the kernel is one extra tick over a user space task spinning in user
space.
available_filter_functions is definitely not a hot path, so I
personally don't care if it were to use "nospin". My worry is about
adding this "special" mutex for a single corner case, and I want to know
that its a real bug before we add something special into the kernel.
-- Steve
next prev parent reply other threads:[~2026-03-05 3:00 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-04 7:46 [RFC PATCH 0/2] disable optimistic spinning for ftrace_lock Yafang Shao
2026-03-04 7:46 ` [RFC PATCH 1/2] locking: add mutex_lock_nospin() Yafang Shao
2026-03-04 9:02 ` Peter Zijlstra
2026-03-04 9:37 ` Yafang Shao
2026-03-04 10:11 ` Peter Zijlstra
2026-03-04 11:52 ` Yafang Shao
2026-03-04 12:41 ` Peter Zijlstra
2026-03-04 14:25 ` Yafang Shao
2026-03-04 9:54 ` David Laight
2026-03-04 20:57 ` Steven Rostedt
2026-03-04 21:44 ` David Laight
2026-03-05 2:17 ` Yafang Shao
2026-03-05 2:28 ` Steven Rostedt
2026-03-05 2:33 ` Yafang Shao
2026-03-05 3:00 ` Steven Rostedt [this message]
2026-03-05 3:08 ` Yafang Shao
2026-03-05 4:30 ` Waiman Long
2026-03-05 5:40 ` Yafang Shao
2026-03-05 13:21 ` Steven Rostedt
2026-03-06 2:22 ` Yafang Shao
2026-03-06 10:00 ` David Laight
2026-03-09 2:34 ` Yafang Shao
2026-03-05 18:34 ` Waiman Long
2026-03-05 18:44 ` Waiman Long
2026-03-06 2:27 ` Yafang Shao
2026-03-05 9:32 ` David Laight
2026-03-05 19:00 ` Waiman Long
2026-03-06 2:33 ` Yafang Shao
2026-03-04 7:46 ` [RFC PATCH 2/2] ftrace: disable optimistic spinning for ftrace_lock Yafang Shao
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