Messages in this thread | | | Subject | Re: [PATCH] perf: Fix RCU dereference check in perf_event_comm | From | Peter Zijlstra <> | Date | Thu, 22 Mar 2012 10:53:16 +0100 |
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On Thu, 2012-03-22 at 01:43 +0200, Ari Savolainen wrote: > The warning below is printed when executing a command like > sudo perf record su - user -c "echo hello" > > It's fixed by moving the call of perf_event_comm to be protected > by the task lock.
That seems like a rather poor solution since it increases the lock hold time for no explained reason.
> include/linux/cgroup.h:567 suspicious rcu_dereference_check() usage!
> [<ffffffff8109be55>] lockdep_rcu_suspicious+0xe5/0x100 > [<ffffffff811131fa>] perf_event_comm+0x37a/0x4d0
So where exactly is this, perf_event_comm_event() takes rcu_read_lock() so I presume its before that.
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