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[Bug runtime/21859] on rawhide, the context.exp test case causes a kernel warning
- From: "dsmith at redhat dot com" <sourceware-bugzilla at sourceware dot org>
- To: systemtap at sourceware dot org
- Date: Fri, 28 Jul 2017 15:45:20 +0000
- Subject: [Bug runtime/21859] on rawhide, the context.exp test case causes a kernel warning
- Auto-submitted: auto-generated
- References: <bug-21859-6586@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=21859
--- Comment #1 from David Smith <dsmith at redhat dot com> ---
The following kernel commit changed module_kallsyms_on_each_symbol(), which is
called by kallsyms_on_each_symbol, to quit doing RCU-style module list
traversal and require the module_mutex:
====
commit 0be964be0d45084245673c971d72a4b51690231d
Author: Peter Zijlstra <peterz@infradead.org>
Date: Wed May 27 11:09:35 2015 +0930
module: Sanitize RCU usage and locking
Currently the RCU usage in module is an inconsistent mess of RCU and
RCU-sched, this is broken for CONFIG_PREEMPT where synchronize_rcu()
does not imply synchronize_sched().
Most usage sites use preempt_{dis,en}able() which is RCU-sched, but
(most of) the modification sites use synchronize_rcu(). With the
exception of the module bug list, which actually uses RCU.
Convert everything over to RCU-sched.
Furthermore add lockdep asserts to all sites, because it's not at all
clear to me the required locking is observed, esp. on exported
functions.
====
It looks like this patch was first included in kernel version 4.2. So, we'll
have to hold the module_mutex when calling kallsyms_on_each_symbol().
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