Re: INFO: suspicious RCU usage. on 3.3.0-rc7-next-20120316

[Justin P. Mattock]

On 03/18/2012 08:54 AM, Tejun Heo wrote:
> On Sun, Mar 18, 2012 at 08:36:26AM -0700, Justin P. Mattock wrote:
> > with the current linux-next I am seeing this in dmesg..:
> >
> > [    3.643089] isapnp: No Plug&  Play device found
> > [    3.643690] Serial: 8250/16550 driver, 32 ports, IRQ sharing enabled
> > [    3.673061]
> > [    3.699307] ===============================
> > [    3.725757] [ INFO: suspicious RCU usage. ]
> > [    3.752134] 3.3.0-rc7-next-20120316 #1 Not tainted
> > [    3.778508] -------------------------------
> > [    3.778510] kernel/cgroup.c:1719 suspicious
> > rcu_dereference_check() usage!
> > [    3.778512]
> > [    3.778512] other info that might help us debug this:
> > [    3.778513]
> > [    3.778515]
> > [    3.778515] rcu_scheduler_active = 1, debug_locks = 1
> > [    3.778517] no locks held by swapper/0/1.
> > [    3.778517]
> > [    3.778518] stack backtrace:
> > [    3.778519] Pid: 1, comm: swapper/0 Not tainted
> > 3.3.0-rc7-next-20120316 #1
> > [    3.778521] Call Trace:
> > [    3.778528]  [<c158cc21>] ? printk+0x1d/0x1f
> > [    3.778534]  [<c10a822a>] lockdep_rcu_suspicious+0xca/0x100
> > [    3.778536]  [<c10bedea>] cgroup_path+0x17a/0x1c0
>
> Known problem.  The following pending patchset should fix the problem.
>
>    http://thread.gmane.org/gmane.linux.kernel/1263989
>
> Jens?
>
> Thakns.

cool thanks for the info..
I went and applied your patches(all 5) and there is fuzz, and some 
errors with linux-next.
seems the suspicious message is still there, but the system boots up 
just fine with the patches in.
 maybe manually applying them by hand is what I need to do for -next so 
I dont miss anything important with the patch that takes care of the 
suspicious message.

Justin P. Mattock
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