Still trying to debug mbuf leak.. Anyone familiar with uma_*?

[Robert Watson]

On Sun, 11 Jan 2009, Jason DiCioccio wrote:

> So I've got various vmcores here from kmem_malloc failures..  I already know 
> that it's an excess of mbufs that's causing the crash, I'm just trying to 
> figure out what the mbufs contain so that I can try and figure out where 
> they came from..
>
> Currently I'm able to get at (uma_zone_t)zone_mbuf, but I'm unsure how to 
> get to the actual mbuf data from there.  I've tried looking the the uma_keg, 
> etc. No luck so far.  Is there anyone familiar with these data structures 
> that could point me in the right direction?

It might require tweaking to work as things have changed a bit, but last time 
I was futzing with the mbuf allocator I put a UMA state dumper into 
src/tools/tools/umastat.  It inspects /dev/kmem (or a core, I suppose) to 
print out the layout of cached data across per-cpu caches, etc.  I'm not sure 
it would be all that useful for debugging a leak, but might prove informative 
for getting a sense of how it fits together, and the source code might be 
useful similarly.

Robert N M Watson
Computer Laboratory
University of Cambridge

>
> (kgdb) p *zone_mbuf
> $66 = {uz_name = 0xc076d6d1 "mbuf", uz_lock = 0xc1048108, uz_keg = 
> 0xc1048100,
> uz_link = {le_next = 0xc1047180, le_prev = 0xc104812c}, uz_full_bucket = {
>   lh_first = 0x0}, uz_free_bucket = {lh_first = 0x0},
> uz_ctor = 0xc05068f0 <mb_ctor_mbuf>, uz_dtor = 0xc0507040 <mb_dtor_mbuf>,
> uz_init = 0, uz_fini = 0, uz_allocs = 137806761, uz_frees = 136018292,
> uz_fails = 136, uz_fills = 4, uz_count = 128, uz_cpu = {{
>     uc_freebucket = 0xc73a8c48, uc_allocbucket = 0x0, uc_allocs = 0,
>     uc_frees = 0}}}
>
> Thanks!
> -JD-
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