From: Oleg Nesterov <oleg@redhat.com>
To: Sebastian Sewior <bigeasy@linutronix.de>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Ziljstra <peterz@infradead.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Andrii Nakryiko <andrii@kernel.org>, bpf <bpf@vger.kernel.org>,
Jiri Olsa <jolsa@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: uprobe splat in PREEMP_RT
Date: Thu, 3 Apr 2025 14:27:56 +0200 [thread overview]
Message-ID: <20250403122756.GB16254@redhat.com> (raw)
In-Reply-To: <20250403073728.c7kEmd8l@linutronix.de>
On 04/03, Sebastian Sewior wrote:
>
> On 2025-04-02 16:12:46 [+0200], Oleg Nesterov wrote:
> > >
> > > Yes. This would work for here just to skip the check because of all
> > > details that are hard to express. Therefore I suggested to use
> > > raw_write_seqcount_begin() instead of write_seqcount_begin() in
> > > 20250402122158.j_8VoHQ-@linutronix.de. Would that work?
> >
> > If this can work, then let me repeat: why can't we turn ->ri_seqcount
> > into a boolean?
>
> I just stumbled here due to the warning. Now that you ask the question,
> it is used a bool in the current construct. So yes, I also don't see
> why.
Well, Andrii has already explained why he decided to abuse seqcount_t,
to avoid the explicti barriers in this code... I won't argue.
So, just in case, I agree that your suggestion to use
raw_write_seqcount_begin/end should obviously fix the problem.
Oleg.
next prev parent reply other threads:[~2025-04-03 12:28 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-01 21:04 uprobe splat in PREEMP_RT Alexei Starovoitov
2025-04-01 21:22 ` Steven Rostedt
2025-04-01 22:01 ` Andrii Nakryiko
2025-04-02 10:33 ` Oleg Nesterov
2025-04-02 10:57 ` Sebastian Sewior
2025-04-02 11:23 ` Oleg Nesterov
2025-04-02 12:13 ` Sebastian Sewior
2025-04-02 12:18 ` Oleg Nesterov
2025-04-02 12:24 ` Sebastian Sewior
2025-04-02 14:12 ` Oleg Nesterov
2025-04-03 7:37 ` Sebastian Sewior
2025-04-03 12:27 ` Oleg Nesterov [this message]
2025-04-03 16:04 ` Andrii Nakryiko
2025-04-02 16:15 ` Andrii Nakryiko
2025-04-02 16:57 ` Oleg Nesterov
2025-04-02 12:21 ` Sebastian Sewior
2025-04-02 9:10 ` Oleg Nesterov
2025-04-02 10:54 ` Sebastian Sewior
2025-04-02 11:20 ` Oleg Nesterov
2025-04-02 11:31 ` Oleg Nesterov
2025-04-02 12:06 ` Sebastian Sewior
2025-04-02 12:12 ` Oleg Nesterov
2025-04-02 12:16 ` Sebastian Sewior
2025-04-02 13:56 ` Oleg Nesterov
2025-04-02 14:23 ` Oleg Nesterov
2025-04-03 9:08 ` Sebastian Sewior
2025-04-03 12:11 ` Oleg Nesterov
2025-04-03 12:43 ` Oleg Nesterov
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