Messages in this thread | | | Date | Mon, 9 Aug 2010 10:13:29 -0700 | From | "Paul E. McKenney" <> | Subject | Re: 2.6.35 - INFO: kernel/signal.c:660 invoked rcu_dereference_check() without protection! |
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On Tue, Aug 03, 2010 at 11:18:07PM -0400, Miles Lane wrote: > [ INFO: suspicious rcu_dereference_check() usage. ] > --------------------------------------------------- > kernel/signal.c:660 invoked rcu_dereference_check() without protection! > > other info that might help us debug this: > > rcu_scheduler_active = 1, debug_locks = 1 > 1 lock held by udevd/670: > #0: (tasklist_lock){.+.+..}, at: [<ffffffff8104628c>] do_exit+0x252/0x671 > stack backtrace: > Pid: 670, comm: udevd Not tainted 2.6.35 #15 > Call Trace: > [<ffffffff8106759c>] lockdep_rcu_dereference+0x9d/0xa6 > [<ffffffff8104f297>] check_kill_permission+0x9d/0x132 > [<ffffffff8105010e>] group_send_sig_info+0x1a/0x3d > [<ffffffff81046388>] do_exit+0x34e/0x671 > [<ffffffff81046723>] do_group_exit+0x78/0xa3 > [<ffffffff81046760>] sys_exit_group+0x12/0x16 > [<ffffffff81009c82>] system_call_fastpath+0x16/0x1b
Thank you again for your testing efforts!
This one is a bit odd. exit_signals() holds either the tasklist_lock or the ->sighand->siglock over its signal manipulations, so this is not the code path triggering the above. I might be missing something, but I don't see either hrtimer_cancel() or exit_itimers() attempting to send signals.
I am copying Oleg, as he might see something that I am missing.
Thanx, Paul
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