On Fri, Nov 2, 2012 at 3:43 PM, Rafael J. Wysocki <r...@sisk.pl> wrote:
>
> Well, not everything is rosy in the suspend land, though. This is a
> failure to freeze khubd during the second in a row attempt to suspend to
> RAM (your current tree):
Ugh. So khubd is blocked in usb_start_wait_urb(), and apparently the
timeout for that block is longer than the freezing timeout.
There's a comment about why khubd needs to be freezable, but I wonder
if that whole thing isn't doing something wrong. Causing the suspend
to fail is definitely always the wrong thing.
Greg?
> [ 125.780766] [ INFO: suspicious RCU usage. ]
> [ 125.780804] 3.7.0-rc3+ #988 Not tainted
> [ 125.780838] -------------------------------
> [ 125.780875] /home/rafael/src/linux/kernel/sched/core.c:4497 suspicious
> rcu_dereference_check() usage!
Heh. The RCU usage is from the debug printout from sched_show_task(),
so it's "related", but it's a totally independent issue.
It's apparently because we've not done a "rcu_read_lock()" around that
sequence, but I seriously doubt we care. But it's technically a real
bug - even if the fix might be to just not print out the parent pid
(or to just ignore the bug and turn the rcu dereference into an
ACCESS_ONCE() or something.
Ingo, Peter, any comments about that sched/core.c:4497 RCU usage?
Linus
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