Re: [PATCH RFC 02/20] ctlv: Add the UAPI wire format and family API

[Yeoreum Yun]

On Tue, Oct 27, 2026 at 12:17:29PM -0300, Jason Gunthorpe wrote:
> On Tue, Oct 27, 2026 at 02:48:19PM +0000, Yeoreum Yun wrote:
> > > On Tue, Oct 27, 2026 at 09:02:14AM +0100, Jiri Pirko wrote:
> > > > Mon, Oct 26, 2026 at 07:55:12PM +0100, yeoreum.yun@xxxxxxx wrote:
> > > > >[    3.856919]  ctlv_schema_check_attr+0x3dc/0x538
> > > > >[    3.857105]  ctlv_schema_check_indexed_nest+0x788/0x958
> > > > >[    3.857301]  ctlv_schema_validate+0x88/0x180
> > > > >[    3.857482]  ctlv_msg_test_as_deep_as_the_core_allows+0x11c/0x1e8
> > > > >[    3.857698]  kunit_try_run_case+0x64/0x188
> > > > >[    3.857878]  kunit_generic_run_threadfn_adapter+0x30/0x68
> > > > >[    3.858086]  kthread+0x10c/0x140
> > > > >[    3.858245]  ret_from_fork+0x10/0x20
> > > > >[    3.858398] SMP: stopping secondary CPUs
> > > > >[    3.858630] Kernel Offset: disabled
> > > > >[    3.858720] CPU features: 0x0,00000000,00b0802e,9f190bc3,2affe72f
> > > > >[    3.858872] Memory Limit: none
> > > > >[    3.858976] ---[ end Kernel panic - not syncing: kernel stack overflow ]---
> > > > >
> > > > >[...]
> > > > >
> > > > >I think it might be good to configurable according to architecture
> > > > >unless it's not good to reduce the CTLV_MAX_NEST_DEPTH number
> > > > >otherwise, increasing stack size when CTLV is enabled seems unresonable...
> > > > 
> > > > Agreed, will lower it down. I think we should be okay with 8 for start.
> > > 
> > > I'm surprised this ran out of stack though with even as few as
> > > 32 levels.. Is there accidently something large on the stack?
> > >
> > 
> > Nope.
> > 
> > When I see the each functions stack allocation:
> > - ctlv_schema_check_indexed_nest():
> > 	sub	sp, sp, #0xf0 // 240 bytes
> > 
> > - ctlv_schema_check_attr():
> > 	sub	sp, sp, #0xb0 // 176 bytes
> > 
> > Roughly (240 + 176) * CTLV_MAX_NEST_DEPTH = 13,952 (around 14KB)
> > consumed.
> 
> 400 bytes per nest seems pretty big to me...
> 
> Do you have debug options enabled or something that increases stack usage?

Actually not, I've used the distribution's Kconfig e.g) ubuntu
+ KSASN.

So, It doesn't seems from side-effect from debug options.

-- 
Sincerely,
Yeoreum Yun