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b=QxXtGlB5xvop4KPOHLJJ9uhHUHE3KOUwrgPRXk+gfjptwpxp93WIyPX4FhBMnVgGv Ihw5+CY0/Tvd2u0WE7c2wKk8GMdkTrIRDjebi2PpUjXvxZCheHtsjfFROdH6ykjQu3 Reb8/2zStv6C1AwE2D90JxOSIOiO4cJducZcmuVFtKwtooI3H4VKNEwy9rzr6KYrEW BOxTyjZ0r4dBwRFIYLa1t6xhnU7TVEM6ohFt16tyy0gR5Sn0BP6HaoBfcv9sZsLfRM gK+DAq8+OPI4cvkz0e+ZQJerj0z1eYaeK51cy77bP3HgMURHzqIUhmtrtzX7l8l+Yb 8n4Fmzh0xqL4A== Date: Tue, 22 Oct 2024 10:51:38 -0700 From: Namhyung Kim To: Martin KaFai Lau Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , LKML , bpf@vger.kernel.org, Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, Arnaldo Carvalho de Melo , Kees Cook Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: Add a test for open coded kmem_cache iter Message-ID: References: <20241017080604.541872-1-namhyung@kernel.org> <20241017080604.541872-2-namhyung@kernel.org> <7b19ad7f-163b-44ed-bc70-f973a7a6f303@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <7b19ad7f-163b-44ed-bc70-f973a7a6f303@linux.dev> X-Rspamd-Queue-Id: 15E8A40006 X-Stat-Signature: 8xjbd3px4qfap778cgx797w9h94wwsdb X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1729619479-960591 X-HE-Meta: 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 BM48VeAi mKDFtTki78kff8wLDf76tOZuCS0Rin/7jFqAVVF0HFrWlc19yqOg1Da7ByZoxJH+3I+sRrNo/XNandEOh7BsL+clI2ILgCi5zQgl7FzkH8/KVWadiP6bglxG72cETGFuiMPYa5bsOqheIVdxMwgGQZEhVHJw/frjMkLLSbNj+jPKm7+wAt64gUHU0MuiaI/Snod9u3iaScaGIR3x5MeRZv4jjINgaqhE/9D6oxvFvnLxRDuQXEwCAp7lz7bhoEk2rS4ABNzt4zVB0u2gumt8f1QElPsUPDhkpA9QPeyyAmv15foq+hut89DbKFlACufS2wZZkWFdXSRryx6j+kHDM/gz7Rh4fVj5THi/VTJTt6rCRF9Vqkc0Lrp2ouwkLZl8ZyNQlrKStXzIJnjY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Oct 18, 2024 at 11:46:31AM -0700, Martin KaFai Lau wrote: > On 10/17/24 1:06 AM, Namhyung Kim 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 > > --- > > .../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; > > + > > #endif > > diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > index 848d8fc9171fae45..a1fd3bc57c0b21bb 100644 > > --- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > @@ -68,12 +68,18 @@ static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) > > fclose(fp); > > } > > +static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel) > > +{ > > + /* To trigger the open coded iterator attached to the syscall */ > > + syncfs(0); > > + > > + /* It should be same as we've seen from the explicit iterator */ > > + ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq"); > > +} > > + > > void test_kmem_cache_iter(void) > > { > > - DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts); > > struct kmem_cache_iter *skel = NULL; > > - union bpf_iter_link_info linfo = {}; > > - struct bpf_link *link; > > char buf[256]; > > int iter_fd; > > @@ -81,16 +87,12 @@ void test_kmem_cache_iter(void) > > if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load")) > > return; > > - opts.link_info = &linfo; > > - opts.link_info_len = sizeof(linfo); > > - > > - link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts); > > - if (!ASSERT_OK_PTR(link, "attach_iter")) > > + if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach")) > > with this change. > > > goto destroy; > > - iter_fd = bpf_iter_create(bpf_link__fd(link)); > > + iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector)); > > if (!ASSERT_GE(iter_fd, 0, "iter_create")) > > - goto free_link; > > + goto detach; > > memset(buf, 0, sizeof(buf)); > > while (read(iter_fd, buf, sizeof(buf) > 0)) { > > @@ -105,11 +107,13 @@ void test_kmem_cache_iter(void) > > subtest_kmem_cache_iter_check_task_struct(skel); > > if (test__start_subtest("check_slabinfo")) > > subtest_kmem_cache_iter_check_slabinfo(skel); > > + if (test__start_subtest("open_coded_iter")) > > + subtest_kmem_cache_iter_open_coded(skel); > > close(iter_fd); > > -free_link: > > - bpf_link__destroy(link); > > +detach: > > + kmem_cache_iter__detach(skel); > > nit. I think the kmem_cache_iter__destroy() below will also detach, so no > need to explicit kmem_cache_iter__detach(). Ok, will remove. > > > destroy: > > kmem_cache_iter__destroy(skel); > > } > > diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > index 72c9dafecd98406b..4c44aa279a5328fe 100644 > > --- a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > @@ -2,6 +2,8 @@ > > /* Copyright (c) 2024 Google */ > > #include "bpf_iter.h" > > +#include "bpf_experimental.h" > > +#include "bpf_misc.h" > > #include > > #include > > @@ -33,6 +35,7 @@ extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; > > /* Result, will be checked by userspace */ > > int task_struct_found; > > int kmem_cache_seen; > > +int open_coded_seen; > > SEC("iter/kmem_cache") > > int slab_info_collector(struct bpf_iter__kmem_cache *ctx) > > @@ -85,3 +88,24 @@ int BPF_PROG(check_task_struct) > > task_struct_found = -2; > > return 0; > > } > > + > > +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") > > +int open_coded_iter(const void *ctx) > > +{ > > + struct kmem_cache *s; > > + > > + bpf_for_each(kmem_cache, s) { > > + struct kmem_cache_result *r; > > + int idx = open_coded_seen; > > + > > + r = bpf_map_lookup_elem(&slab_result, &idx); > > + if (r == NULL) > > + break; > > + > > + open_coded_seen++; > > I am not sure if this will work well if the testing system somehow has > another process calling syncfs. It is probably a good idea to guard this by > checking the tid of the test_progs at the beginning of this bpf prog. Right, I'll add the tid check. Thanks for the review, Namhyung