Re: [patch] corrupt memstat_kvm_malloc(3) output and dtrace

On Friday 15 May 2009 1:17:09 pm Ben Kelly wrote:
> On May 12, 2009, at 10:28 AM, John Baldwin wrote:
> > On Wednesday 06 May 2009 1:00:09 am Ben Kelly wrote:
> >> On May 5, 2009, at 10:18 AM, Ben Kelly wrote:
> >>> While debugging a problem recently with Alexander Leidinger we
> >>> noticed that crashinfo(8) was producing corrupt vmstat -m output.
> >>> After doing some digging it appears that memstat_kvm_malloc(3) might
> >>> have been broken by this commit:
> >>>
> >>> http://svn.freebsd.org/viewvc/base?view=revision&revision=179222
> >>>
> >>> The problem is that memstat_kvm_malloc(3) assumes that
> >>> malloc_type_internal starts with an array of malloc_types_stats
> >>> structures.  This assumption is no longer true, though, as
> >>> mti_probes was inserted at the start of the structure.
> >>>
> >>> It appears that this (untested) patch might fix the problem:
> >>>
> >>> http://www.wanderview.com/svn/public/misc/zfs/vmstat_kvm_malloc.diff
> >>>
> >>> I'm not very familiar with dtrace, though.  Does anyone know if this
> >>> would cause problems?
> >>
> >> Just FYI, I was able to recompile and test this patch tonight.  It
> >> seems to have fixed vmstat -M $core -m output on my machine.
> >
> > I think that it would be better to update memstat_kvm_malloc(3)  
> > though.  I'm
> > also curious why libmemstat isn't just using malloc_types_internal  
> > directly.
> 
> I've updated the patch so that  memstat_kvm_malloc(3) uses the  
> malloc_type_internal definition to find the start of the statistics  
> array.  This also appears to fix the problem on my server.

Thanks!  I've committed the fix.

-- 
John Baldwin