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From: Sven Schnelle <svens@linux.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org
Subject: Re: ftrace startup tests crashing due to missing rcu_synchronize()
Date: Wed, 16 Feb 2022 20:31:37 +0100	[thread overview]
Message-ID: <yt9da6eq4nhi.fsf@linux.ibm.com> (raw)
In-Reply-To: <20220216135821.67a22c52@gandalf.local.home> (Steven Rostedt's message of "Wed, 16 Feb 2022 13:58:21 -0500")

Steven Rostedt <rostedt@goodmis.org> writes:

> On Wed, 16 Feb 2022 13:54:19 -0500
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
>> That is, shutdown is called, the item is removed from the list and freed,
>> but something got preempted while on the ftrace trampoline, with a
>> reference to the item, and then woke up and executed the item that was
>> freed.
>> 
>> I'll look into it. Thanks for the report.
>
> OK, I wonder if something changed with "is_kernel_core_date()"?
>
> Because on registering, we have:
>
> 	if (!is_kernel_core_data((unsigned long)ops))
> 		ops->flags |= FTRACE_OPS_FL_DYNAMIC;

I checked, and the flag gets set here. I cannot say whether it
is also set when the system crashes, but i would expect it.

  reply	other threads:[~2022-02-16 19:32 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-16 18:39 ftrace startup tests crashing due to missing rcu_synchronize() Sven Schnelle
2022-02-16 18:54 ` Steven Rostedt
2022-02-16 18:58   ` Steven Rostedt
2022-02-16 19:31     ` Sven Schnelle [this message]
2022-02-16 19:23   ` Sven Schnelle

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