Re: [TIP,BISECTED] Negative nice values have become big positive numbers

[Ingo Molnar <mingo@elte.hu>]

* Steven Rostedt <rostedt@goodmis.org> wrote:

> On Sun, 8 Mar 2009, Sitsofe Wheeler wrote:
> 
> > (Forgot to cc lkml. Resending...)
> > 
> > Formally negative nice values have started become very big in positive
> > integers in -tip kernels:
> > 
> >     2 root      15 2147483647     0    0    0 S  0.0  0.0   0:00.00 kthreadd    
> 
> Is this the output of top?

seems so.

> > I've just finished bisecting down to this commit:
> > 
> > commit 1427cdf0592368bdec57276edaf714040ee8744f
> > Author: Lai Jiangshan <laijs@cn.fujitsu.com>
> > Date:   Fri Mar 6 17:21:47 2009 +0100
> 
> $ git show 1427cdf0592368bdec57276edaf714040ee8744f  | diffstat
>  include/linux/ftrace.h       |    3 +
>  kernel/trace/Kconfig         |    6 ++
>  kernel/trace/Makefile        |    1 
>  kernel/trace/trace.c         |   56 +++++++++++++++++++++++++++
>  kernel/trace/trace.h         |   12 +++++
>  kernel/trace/trace_bprintk.c |   87 
> +++++++++++++++++++++++++++++++++++++++++++
>  kernel/trace/trace_output.c  |   75 +++++++++++++++++++++++++++++++++++++
>  7 files changed, 240 insertions(+)
> 
> I find it hard to believe that this would cause normal nice 
> values to be messed up. The only file that could could come 
> close to messing with nice values in top is ftrace.h:

Correct - maybe it's these two nearby commits that cause the 
problems:

 fef20d9: vsprintf: unify the format decoding layer for its 3 users
 4370aa4: vsprintf: add binary printf

they do affect generic code. If we broke vsnprintf (which the 
nice value output code uses) then that might be a plausible 
explanation.

	Ingo