Re: 2.6.36-git11 -- kernel/pid.c:419 invokedrcu_dereference_check() without protection!

[Paul E. McKenney]

On Mon, Nov 08, 2010 at 04:00:51PM -0500, Miles Lane wrote:
> Great!  Works here.  :-)

Thank you for testing it, Miles!

							Thanx, Paul

> On Sun, Nov 7, 2010 at 1:47 PM, Paul E. McKenney
> <paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> > On Fri, Oct 29, 2010 at 01:22:28AM -0400, Miles Lane wrote:
> >> [ INFO: suspicious rcu_dereference_check() usage. ]
> >> ---------------------------------------------------
> >> kernel/pid.c:419 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 ureadahead/943:
> >>  #0:  (tasklist_lock){.+.+..}, at: [<ffffffff810ec497>]
> >> sys_ioprio_set+0x8e/0x2aa
> >>
> >> stack backtrace:
> >> Pid: 943, comm: ureadahead Not tainted 2.6.36-git11 #8
> >> Call Trace:
> >>  [<ffffffff8105d335>] lockdep_rcu_dereference+0x9d/0xa5
> >>  [<ffffffff8104c825>] find_task_by_pid_ns+0x3f/0x58
> >>  [<ffffffff8104c85b>] find_task_by_vpid+0x1d/0x1f
> >>  [<ffffffff810ec4c6>] sys_ioprio_set+0xbd/0x2aa
> >>  [<ffffffff813547a3>] ? trace_hardirqs_on_thunk+0x3a/0x3f
> >>  [<ffffffff81002aab>] system_call_fastpath+0x16/0x1b
> >
> > Could you please try the patch from Sergey Senozhatsky, currently
> > in -mm, that may be found at http://lkml.org/lkml/2010/10/29/168?
> >
> >                                                        Thanx, Paul
> >
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