Re: [Bug 12832] New: kernel leaks a lot of memory

[Wu Fengguang <fengguang.wu@intel.com>]

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On Wed, Mar 11, 2009 at 09:26:58AM +0200, Pierre Ossman wrote:
> On Wed, 11 Mar 2009 15:14:45 +0800
> Wu Fengguang <fengguang.wu@intel.com> wrote:
> 
> > On Wed, Mar 11, 2009 at 08:57:03AM +0200, Pierre Ossman wrote:
> > > On Wed, 11 Mar 2009 09:37:40 +0800
> > > Wu Fengguang <fengguang.wu@intel.com> wrote:
> > > 
> > > > 
> > > > This 80MB noflags pages together with the below 80MB lru pages are
> > > > very close to the missing page numbers :-) Could you run the following
> > > > commands on fresh booted 2.6.27 and post the output files? Thank you!
> > > > 
> > > >         dd if=/dev/zero of=/tmp/s bs=1M count=1 seek=1024
> > > >         cp /tmp/s /dev/null
> > > > 
> > > >         ./page-flags > flags
> > > >         ./page-areas =0x20000 > areas-noflags
> > > >         ./page-areas =0x00020 > areas-lru
> > > > 
> > > 
> > > Attached.
> > 
> > Thank you very much!
> > 
> > > I have to say, the patterns look very much like some kind of leak.
> > 
> > Wow it looks really interesting.  The lru pages and noflags pages make
> > perfect 1-page interleaved pattern...
> > 
> 
> Another breakthrough. I turned off everything in kernel/trace, and now
> the missing memory is back. Here's the relevant diff against the
> original .config:
> 
> @@ -3677,18 +3639,15 @@
>  # CONFIG_BACKTRACE_SELF_TEST is not set
>  # CONFIG_LKDTM is not set
>  # CONFIG_FAULT_INJECTION is not set
> -CONFIG_LATENCYTOP=y
> +# CONFIG_LATENCYTOP is not set
>  # CONFIG_SYSCTL_SYSCALL_CHECK is not set
>  CONFIG_HAVE_FTRACE=y
>  CONFIG_HAVE_DYNAMIC_FTRACE=y
> -CONFIG_TRACER_MAX_TRACE=y
> -CONFIG_TRACING=y
>  # CONFIG_FTRACE is not set
> -CONFIG_IRQSOFF_TRACER=y
> -CONFIG_SYSPROF_TRACER=y
> -CONFIG_SCHED_TRACER=y
> -CONFIG_CONTEXT_SWITCH_TRACER=y
> -# CONFIG_FTRACE_STARTUP_TEST is not set
> +# CONFIG_IRQSOFF_TRACER is not set
> +# CONFIG_SYSPROF_TRACER is not set
> +# CONFIG_SCHED_TRACER is not set
> +# CONFIG_CONTEXT_SWITCH_TRACER is not set
> 
> I'll enable them one at a time and see when the bug reappears, but if
> you have some ideas on which it could be, that would be helpful. The
> machine takes some time to recompile a kernel. :)

A quick question: are there any possibility of ftrace memory reservation?

Thanks,
Fengguang

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