linux-kernel - Re: [PATCH bpf-next 2/2] selftests/bpf: Add a test for open coded kmem

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Message-ID: <Zxn62WotvxH0UZ_h@google.com>
Date: Thu, 24 Oct 2024 00:44:25 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
	Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>, bpf@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Hyeonggon Yoo <42.hyeyoo@...il.com>, linux-mm@...ck.org,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Kees Cook <kees@...nel.org>
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: Add a test for open coded
 kmem_cache iter

On Mon, Oct 21, 2024 at 04:36:49PM -0700, Andrii Nakryiko wrote:
> On Thu, Oct 17, 2024 at 1:06 AM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > The new subtest is attached to sleepable fentry of syncfs() syscall.
> > It iterates the kmem_cache using bpf_for_each loop and count the number
> > of entries.  Finally it checks it with the number of entries from the
> > regular iterator.
> >
> >   $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter
> >   ...
> >   #130/1   kmem_cache_iter/check_task_struct:OK
> >   #130/2   kmem_cache_iter/check_slabinfo:OK
> >   #130/3   kmem_cache_iter/open_coded_iter:OK
> >   #130     kmem_cache_iter:OK
> >   Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED
> >
> > Also simplify the code by using attach routine of the skeleton.
> >
> > Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> > ---
> >  .../testing/selftests/bpf/bpf_experimental.h  |  6 ++++
> >  .../bpf/prog_tests/kmem_cache_iter.c          | 28 +++++++++++--------
> >  .../selftests/bpf/progs/kmem_cache_iter.c     | 24 ++++++++++++++++
> >  3 files changed, 46 insertions(+), 12 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
> > index b0668f29f7b394eb..cd8ecd39c3f3c68d 100644
> > --- a/tools/testing/selftests/bpf/bpf_experimental.h
> > +++ b/tools/testing/selftests/bpf/bpf_experimental.h
> > @@ -582,4 +582,10 @@ extern int bpf_wq_set_callback_impl(struct bpf_wq *wq,
> >                 unsigned int flags__k, void *aux__ign) __ksym;
> >  #define bpf_wq_set_callback(timer, cb, flags) \
> >         bpf_wq_set_callback_impl(timer, cb, flags, NULL)
> > +
> > +struct bpf_iter_kmem_cache;
> > +extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym;
> > +extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym;
> > +extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym;
> > +
> 
> we should be getting this from vmlinux.h nowadays, so this is probably
> unnecessary

I got some build errors without this.  I'll leave it for v2.

Thanks,
Namhyung