How to detect slab memory leak

[Mulyadi Santosa]

On Wed, Dec 19, 2018 at 6:58 PM Naruto Nguyen <narutonguyen2018 at gmail.com>
wrote:

> Hi Harsh and Mulyadi,
>
> Thanks a lot  for your reply.
>
> Just another question, in the slabtop output, I see that we have
> kmalloc-64 and kmalloc-96 cache, when these caches increase their
> size, is it calculated in the "cache" of the "free" command or in
> "used".


If the cache is used for page cache related operations, then AFAIK it is
calculated in cache. If not, say for mmap non file backed operation, then
it is calculated in overall used.


> Is it reclaimable?


AFAIK yes, as long as it is not locked after being allocated.


> and count in SReclaimable or SUnreclaim of
> cat /proc/meminfo? I know some cache like dentry or inode cache will
> be calculated in "cache" of free command output and SReclaimable of
> cat /proc/meminfo and can be freed by "echo 3 >
> /proc/sys/vm/drop_caches" but not sure if it the same situation for
> kmalloc-64 and kmalloc-96 cache.
>
> Thanks again,
> Brs,
> Bao
>
> On Tue, 18 Dec 2018 at 15:31, Harsh Jain <harshjain.prof at gmail.com> wrote:
> >
> > You can try kernel config option "CONFIG_DEBUG_KMEMLEAK".
> >
> >
> > https://www.kernel.org/doc/html/v4.10/dev-tools/kmemleak.html
> >
> > On Tue, Dec 18, 2018 at 1:14 PM Mulyadi Santosa
> > <mulyadi.santosa at gmail.com> wrote:
> > >
> > >
> > >
> > > On Sun, Dec 16, 2018 at 1:25 PM Naruto Nguyen <
> narutonguyen2018 at gmail.com> wrote:
> > >>
> > >> Hi everyone,
> > >>
> > >> When using slabtop to display the cache size growing, I see that
> > >> kmalloc-1024 and kmalloc-256 are increasing about 200MB after 1 hour.
> > >> Is there any way to detect which kernel components cause this slab
> > >> increase?
> > >>
> > >> Thanks a lot,
> > >> Brs,
> > >> Naruto
> > >>
> > >
> > > Hello Naruto
> > >
> > > I think you can do it by instrumenting call to kmalloc(). These days,
> eBPF is the hot stuff to try for this matter. See if it fits yours too.
> > >
> > > regards,
> > >
> > > Mulyadi
> > >
> > >>
> > >> _______________________________________________
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> > >
> > >
> > >
> > > --
> > > regards,
> > >
> > > Mulyadi Santosa
> > > Freelance Linux trainer and consultant
> > >
> > > blog: the-hydra.blogspot.com
> > > training: mulyaditraining.blogspot.com
> > > _______________________________________________
> > > Kernelnewbies mailing list
> > > Kernelnewbies at kernelnewbies.org
> > > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>


-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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