linux-kernel - Re: [PATCH v4 9/9] riscv: Fixup lockdep_assert_held(&text_mutex) in patch_insn

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Message-ID: <20201020164121.32626e45@gandalf.local.home>
Date:   Tue, 20 Oct 2020 16:41:21 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Guo Ren <guoren@...nel.org>
Cc:     Atish Patra <atishp@...shpatra.org>, Zong Li <zong.li@...ive.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alan Kao <alankao@...estech.com>,
        Patrick Stählin <me@...ki.ch>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Anup Patel <anup@...infault.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        linux-csky@...r.kernel.org, Greentime Hu <greentime.hu@...ive.com>,
        linux-riscv <linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v4 9/9] riscv: Fixup lockdep_assert_held(&text_mutex) in
 patch_insn_write

On Tue, 20 Oct 2020 19:18:01 +0800
Guo Ren <guoren@...nel.org> wrote:

> > What platform are you testing ? We are seeing a crash while enabling
> > any of the tracers multiple times
> > on Qemu/HiFive Unleashed.  
> I use qemu for testing. I've changed dynamic ftrace mechanism from
> mcount to -fpatchable-entry.
> 
> The problem is made by the lockdep checking of text_mutex.

If you are switching to "patchable-entry" you shouldn't need to use
stop_machine for the updates. No?

-- Steve