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

From: Miles Lane
Date: Mon Nov 08 2010 - 16:00:56 EST


Great! Works here. :-)

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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