Messages in this thread | | | From | Linus Torvalds <> | Date | Fri, 2 Nov 2012 16:10:34 -0700 | Subject | Re: Linux 3.7-rc3 |
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On Fri, Nov 2, 2012 at 3:43 PM, Rafael J. Wysocki <rjw@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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