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AJvYcCXoVqGqnyRRXqoOQmmZ0YjY0VXKzUnmo6sg0qjhn97Mr/ot9rwyUFCSJ2rzf348Jax0yagaaJbXUQ==@kvack.org X-Gm-Message-State: AOJu0YyMQx2eultgtWa+lS+yvn+WgVZqcpvaonp5O7thk9hpmGFtWw9K 7a7SxCupbTYwsz2HCLSnETwQSKk+Q9h2+e2uBxD1p74dF7at/7EYjbRF32Qjm1Tjfoe6zpxi9mG 1KoKEiOPJGOu3SoVvHvxTnM4slTEqZw== X-Google-Smtp-Source: AGHT+IHtADTjFNUiOzcBVHGFK5fqjvzcuZ7N+Bfv/1XzpGRD1qXsWzbAsnucAxaxXvqPWA1Qj0dWpGn3l4Oxl/cKIyw= X-Received: by 2002:a05:600c:1c12:b0:42d:a024:d6bb with SMTP id 5b1f17b1804b1-4318422075dmr51336225e9.20.1729793291786; Thu, 24 Oct 2024 11:08:11 -0700 (PDT) MIME-Version: 1.0 References: <20241024074815.1255066-1-namhyung@kernel.org> <20241024074815.1255066-2-namhyung@kernel.org> In-Reply-To: <20241024074815.1255066-2-namhyung@kernel.org> From: Alexei Starovoitov Date: Thu, 24 Oct 2024 11:08:00 -0700 Message-ID: Subject: Re: [PATCH v2 bpf-next 2/2] selftests/bpf: Add a test for open coded kmem_cache iter To: Namhyung Kim 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 837C91C0012 X-Stat-Signature: xfh8uwua4oot4e5bs16gmzy6exoa3z5j X-Rspam-User: X-HE-Tag: 1729793270-592864 X-HE-Meta: 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 4M+tYBMB 5KW+XaeWuGD118iD5sMd23VYRJ2NX6DKRiw9mzD7auGv0vd6QpDwUREWJU6KiUlgb6wp7NXDzBUsmMYWdTZUSisbMx6AklQHhFoOUFBAqsKYhI4oyFuUiKXH51uPPFGjmCyerNtmW9rOHI3Pp4BnhxHUwefsxKMEoIyeUKPyAVtyL0za58/j/7U2EUm7DHRrOFzbIu5/UZ9QHC3xBbW4IC8PhsU87hUKMzzvwxs3qvXk+Kq7DJVekWiavS7a1jKYU3XwqhNWIk2ENmcj4yol5ksgYnatqB+730Fh3ilFDqzDparIeakWbOsdkT2ZzOH8CWgVRwMj/dJfneLJeZ5/fAGHJ2/M3XmFTIynczE9czyvdfITWWRjI9RIXLeXNdyL5z2TZwaLQol+aCK5UAyZTy0etdyJIOXELvJCkNVQRwoEM+Yx8uPGDRGiULSnWtRMd2TuNBtSr8JaKz8ZWSrlPc7PGK0yzV3JKxFPuKzGjljoTMBw= 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 Thu, Oct 24, 2024 at 12:48=E2=80=AFAM 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/testi= ng/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 *w= q, > 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) __wea= k __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/t= ools/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(st= ruct kmem_cache_iter *skel) > fclose(fp); > } > > +static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *s= kel) > +{ > + skel->bss->tgid =3D 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 =3D NULL; > - union bpf_iter_link_info linfo =3D {}; > - 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 =3D &linfo; > - opts.link_info_len =3D sizeof(linfo); > - > - link =3D 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 =3D bpf_iter_create(bpf_link__fd(link)); > + iter_fd =3D bpf_iter_create(bpf_link__fd(skel->links.slab_info_co= llector)); > 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 =3D -2; > return 0; > } > + > +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") > +int open_coded_iter(const void *ctx) > +{ > + struct kmem_cache *s; > + > + if (tgid !=3D 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. > + > + bpf_for_each(kmem_cache, s) { > + struct kmem_cache_result *r; > + > + r =3D bpf_map_lookup_elem(&slab_result, &open_coded_seen)= ; > + if (!r) > + break; > + > + open_coded_seen++; > + > + if (r->obj_size !=3D s->size) > + break; The order of 'if' and ++ should probably be changed ? Otherwise the last object isn't sufficiently checked. pw-bot: cr