From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-183.mta1.migadu.com (out-183.mta1.migadu.com [95.215.58.183]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7EFDD20409D for ; Fri, 18 Oct 2024 18:46:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.183 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729277211; cv=none; b=NTmyFZBrhaNR4aqGI3Y3Ia75GvuRO10YU19wY/kQ51xWRKPf2U5PEm5eA2h+0uUQn9d8KC81uv7leXKUjeNg39oka9tdcwcptSyucACw48Zq1DqCdlhKDBWXfscQFb68Nryv3Pil6aQHU8AwEmX1HYwBS8aslFqIU2ZBLFfDyhw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729277211; c=relaxed/simple; bh=h8TYANH/Rm3VFpXirJ+fPVzaqM04U3Ots8fYgrPYztA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AeyQ8ifRKug/P7doorGahiot5aZFEDvik/GfbReg8cUpq0lPJlw6GLnPWOQryqG84mFopM/Ye4qT7xLYE7V/+vZfVbRxhNnmNH/s6i1MxyuvJXwNktdw4hSMLGiAMMPUQTlMLcUzIlJCfIkVdWVeXbpLQhrI3onQtlmUlbC5LSM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=qDW83nvb; arc=none smtp.client-ip=95.215.58.183 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="qDW83nvb" Message-ID: <7b19ad7f-163b-44ed-bc70-f973a7a6f303@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1729277202; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+qWqLaFRsovCSA73a8GFikArTFdEXCAPGRK8EgBnsBI=; b=qDW83nvbu1D1nHDB9IU/Lb4Oq1RVpDDQgbBui4S6YZZh795i4+Og3uj3SyMb+WEFtTzKdq 6DEKsEGo1walFPw61yxeCpWlRQBOqhGwkHE87ESRhNYg8nZmu6FmzFvnD4Psf71Vcer0FU MaTjIHY/Sw8DuOnBmH//5Qy0VJMEcbE= Date: Fri, 18 Oct 2024 11:46:31 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 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 , 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 References: <20241017080604.541872-1-namhyung@kernel.org> <20241017080604.541872-2-namhyung@kernel.org> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: <20241017080604.541872-2-namhyung@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT 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(). > 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. > + > + if (r->obj_size != s->size) > + break; > + } > + return 0; > +}