From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: WARNING at arch/x86/kernel/alternative.c:707 text_poke+0x25d/0x270
Date: Tue, 16 May 2017 11:30:19 -0400 [thread overview]
Message-ID: <20170516113019.0bfcd516@gandalf.local.home> (raw)
In-Reply-To: <20170517001539.171b05fd39bbdd4ce36566c2@kernel.org>
On Wed, 17 May 2017 00:15:39 +0900
Masami Hiramatsu <mhiramat@kernel.org> wrote:
> > It appears that the kprobe_optimizer work thread call happened after
> > the init pages were freed, causing alternative.c to give the above
> > warning because the text that is being unoptimized happens to no longer
> > exist.
>
> Ah, I see. I need to check that case. Actually for the module
> init text area, kill_kprobe() correctly kicks kill_optimized_kprobe()
> so it should safe. But above case is on the init-text in kernel
> itself. I guess module_notifier may not be called for that area...
Hmm, what happens if you add a kprobe to a module, remove it, and then
remove the module. If the module is still loaded when it is removed,
wouldn't that cause the optimized probe to be delayed? Wouldn't that
open a race where the optimizer work queue can be called when no module
exists?
-- Steve
next prev parent reply other threads:[~2017-05-16 15:30 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-16 13:48 WARNING at arch/x86/kernel/alternative.c:707 text_poke+0x25d/0x270 Steven Rostedt
2017-05-16 15:15 ` Masami Hiramatsu
2017-05-16 15:30 ` Steven Rostedt [this message]
2017-05-16 16:27 ` Masami Hiramatsu
2017-05-16 21:42 ` Thomas Gleixner
2017-05-17 1:38 ` Masami Hiramatsu
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