Re: [PATCH] tools/cgroup/slabinfo: Fix use of slab.memcg_data

[Hongfu Li]

Hi Hao,

Thanks for your review.

> > +def objexts_flags_mask():
> > +    try:
> > +        return int(prog.constant('__NR_OBJEXTS_FLAGS')) - 1
> > +    except:
> > +        return 0x7
> > +
> > +
> >   def find_memcg_ids(css=prog['root_mem_cgroup'].css, prefix=''):
> >       if not list_empty(css.children.address_of_()):
> >           for css in list_for_each_entry('struct cgroup_subsys_state',
> > @@ -192,23 +199,24 @@ def main():
> >           # look over all slab folios and look for objects belonging
> >           # to the given memory cgroup
> >           for slab in for_each_slab(prog):
> > -            objcg_vec_raw = slab.memcg_data.value_()
> > -            if objcg_vec_raw == 0:
> > +            objext_vec_raw = slab.obj_exts.value_()
> 
> Here, we should also check whether it equals OBJEXTS_ALLOC_FAIL,
> 
> which indicates that the allocation of obj_exts has failed, Or have I 
> missed something here?

An obj_ext with the OBJEXTS_ALLOC_FAIL flag may not belong to any cgroup.
Should we add a check and break this round of polling, or add a comment
explaining this scenario?

Best Regards,
Hongfu