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b=m1wDC+e0paXoDcn9gnQzyMX/g5ei9EqANcNC3ksKuzs/b9pcE8o0kVO11JEc5BHwT CP8DS4fiRAWmpYKu41iHn7poD5sQFsWiD3uYMbO4zWgHxbuWsDnHl1Fj7TL/Sjattu oUeJLYvD0u+0YC1+NSy/Nxi3XylvlCC6WmKSmgTvRIOcob781komIbXj877DJ/OA2A +7415a0w7wnuESKNDHFLFoT4DCroDnkFHuXhlhTGYIqKNntJW3r23CGZAaJUD3g/jW pg02EW8IbpaREcu/JdqKuXNckYDkdnfRo/oOneWJz4IhcxoKDyIkCNkbp2ljZReKq2 hm/49Qc2MlhgQ== Date: Tue, 29 Oct 2024 18:40:46 -0700 From: Namhyung Kim To: Alexei Starovoitov Cc: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , LKML , bpf , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm , Arnaldo Carvalho de Melo , Kees Cook Subject: Re: [PATCH v2 bpf-next 2/2] selftests/bpf: Add a test for open coded kmem_cache iter Message-ID: References: <20241024074815.1255066-1-namhyung@kernel.org> <20241024074815.1255066-2-namhyung@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BE9FA20007 X-Stat-Signature: 7s7tsezut4dpx7ttwfdp3qzgtzb1dmwa X-HE-Tag: 1730252440-977667 X-HE-Meta: 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 v4o+x9Cf jufsVWAX2cM27f8pNzQ0f7tUltj+4uQIbgxK1TlOSTCQAQw5/Y4ptjwVPaTXkKW2NvqSywtxh6PzluxRBMZ97Y8QW0ISAB0QNHBvPpajsNBlWLw12BBsE3C6Rg9BjKQv3UBPIm2mkFp+Ub0Bmt7rNJT8q8OkRZw62QRwtsUY8Ta7XXh+lTAaWVyJKPiA6+CAjeVjvVPouJkbaqBdZ+ULBvymEcWcpO5ZQy00X1IkSlFkqTVIOXLzEz5lVd7jogVRZHpuIVLFuLfd7LX0K0t/iVRblh/ETQq/rBNVtvNcOFrIuVOocZugir6L26d96QTLkV46Lc73OdC9vGttdIrhf9jRMZi7ih4X4PRZcucBBZA9ipUcx2wWPllyPQM+9M9tJAhMksEkD0SiLYoGcCdmrw+Ex0yeWCOty1iNK 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: Hello, On Thu, Oct 24, 2024 at 11:08:00AM -0700, Alexei Starovoitov wrote: > On Thu, Oct 24, 2024 at 12:48 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 > > --- > > v2) > > * remove unnecessary detach (Martin) > > * check pid in syncfs to prevent surprise (Martin) > > * remove unnecessary local variable (Andrii) > > > > .../testing/selftests/bpf/bpf_experimental.h | 6 ++++ > > .../bpf/prog_tests/kmem_cache_iter.c | 28 +++++++++++-------- > > .../selftests/bpf/progs/kmem_cache_iter.c | 28 +++++++++++++++++++ > > 3 files changed, 50 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..778b55bc1f912b98 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 +68,20 @@ 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) > > +{ > > + skel->bss->tgid = getpid(); > > + > > + /* 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 +89,12 @@ 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")) > > 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 destroy; > > > > memset(buf, 0, sizeof(buf)); > > while (read(iter_fd, buf, sizeof(buf) > 0)) { > > @@ -105,11 +109,11 @@ 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); > > 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..e62807caa7593604 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 > > > > @@ -30,9 +32,12 @@ struct { > > > > extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; > > > > +unsigned int tgid; > > + > > /* 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 +90,26 @@ 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; > > + > > + if (tgid != bpf_get_current_pid_tgid() >> 32) > > + return 0; > > Pls use syscall prog type and prog_run() it. > No need to attach to exotic syscalls and filter by pid. Sure, will update in v3. > > > + > > + bpf_for_each(kmem_cache, s) { > > + struct kmem_cache_result *r; > > + > > + r = bpf_map_lookup_elem(&slab_result, &open_coded_seen); > > + if (!r) > > + break; > > + > > + open_coded_seen++; > > + > > + if (r->obj_size != s->size) > > + break; > > The order of 'if' and ++ should probably be changed ? > Otherwise the last object isn't sufficiently checked. I don't think so. The last element should be an actual slab cache and then the iterator will return NULL to break the loop. I don't expect it will hit the if statement. Thanks, Namhyung