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([2600:1700:6cf8:1240:89d2:1af8:8439:b81]) by smtp.gmail.com with ESMTPSA id c15-20020a25c00f000000b00d9a43500f1dsm3860785ybf.28.2023.10.24.14.29.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 24 Oct 2023 14:29:21 -0700 (PDT) Message-ID: <041a3ea2-8cc6-4f0f-8ed9-6ca459e5bbb7@gmail.com> Date: Tue, 24 Oct 2023 14:29:19 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf-next] selftests/bpf: umount children of TDIR in test_bpffs Content-Language: en-US To: Manu Bretelle , bpf@vger.kernel.org, andrii@kernel.org, daniel@iogearbox.net, ast@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, mykolal@fb.com, shuah@kernel.org References: <20231024201852.1512720-1-chantr4@gmail.com> From: Kui-Feng Lee In-Reply-To: <20231024201852.1512720-1-chantr4@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/24/23 13:18, Manu Bretelle wrote: > Currently this tests tries to umount /sys/kernel/debug (TDIR) but the > system it is running on may have mounts below. > > For example, danobi/vmtest [0] VMs have > mount -t tracefs tracefs /sys/kernel/debug/tracing > as part of their init. > > This change list mounts and will umount any mounts below TDIR before > umounting TDIR itself. > > Note that it is not umounting recursively, so in the case of a sub-mount > of TDIR having another sub-mount, this will fail as mtab is ordered. Should we move TID to a random path likes "/sys/kernel/debug-/"? > > Test: > > Originally: > > $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs" > => bzImage > ===> Booting > ===> Setting up VM > ===> Running command > [ 2.138818] bpf_testmod: loading out-of-tree module taints kernel. > [ 2.140913] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel > bpf_testmod.ko is already unloaded. > Loading bpf_testmod.ko... > Successfully loaded bpf_testmod.ko. > test_test_bpffs:PASS:clone 0 nsec > fn:PASS:unshare 0 nsec > fn:PASS:mount / 0 nsec > fn:FAIL:umount /sys/kernel/debug unexpected error: -1 (errno 16) > bpf_testmod.ko is already unloaded. > Loading bpf_testmod.ko... > Successfully loaded bpf_testmod.ko. > test_test_bpffs:PASS:clone 0 nsec > test_test_bpffs:PASS:waitpid 0 nsec > test_test_bpffs:FAIL:bpffs test failed 255#282 test_bpffs:FAIL > Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED > Successfully unloaded bpf_testmod.ko. > Command failed with exit code: 1 > > After this change: > > $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs" > => bzImage > ===> Booting > ===> Setting up VM > ===> Running command > [ 2.035210] bpf_testmod: loading out-of-tree module taints kernel. > [ 2.036510] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel > bpf_testmod.ko is already unloaded. > Loading bpf_testmod.ko... > Successfully loaded bpf_testmod.ko. > test_test_bpffs:PASS:clone 0 nsec > fn:PASS:unshare 0 nsec > fn:PASS:mount / 0 nsec > fn:PASS:accessing /etc/mtab 0 nsec > fn:PASS:umount /sys/kernel/debug/tracing 0 nsec > fn:PASS:umount /sys/kernel/debug 0 nsec > fn:PASS:mount tmpfs 0 nsec > fn:PASS:mkdir /sys/kernel/debug/fs1 0 nsec > fn:PASS:mkdir /sys/kernel/debug/fs2 0 nsec > fn:PASS:mount bpffs /sys/kernel/debug/fs1 0 nsec > fn:PASS:mount bpffs /sys/kernel/debug/fs2 0 nsec > fn:PASS:reading /sys/kernel/debug/fs1/maps.debug 0 nsec > fn:PASS:reading /sys/kernel/debug/fs2/progs.debug 0 nsec > fn:PASS:creating /sys/kernel/debug/fs1/a 0 nsec > fn:PASS:creating /sys/kernel/debug/fs1/a/1 0 nsec > fn:PASS:creating /sys/kernel/debug/fs1/b 0 nsec > fn:PASS:create_map(ARRAY) 0 nsec > fn:PASS:pin map 0 nsec > fn:PASS:stat(/sys/kernel/debug/fs1/a) 0 nsec > fn:PASS:renameat2(/fs1/a, /fs1/b, RENAME_EXCHANGE) 0 nsec > fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec > fn:PASS:b should have a's inode 0 nsec > fn:PASS:access(/sys/kernel/debug/fs1/b/1) 0 nsec > fn:PASS:stat(/sys/kernel/debug/fs1/map) 0 nsec > fn:PASS:renameat2(/fs1/c, /fs1/b, RENAME_EXCHANGE) 0 nsec > fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec > fn:PASS:b should have c's inode 0 nsec > fn:PASS:access(/sys/kernel/debug/fs1/c/1) 0 nsec > fn:PASS:renameat2(RENAME_NOREPLACE) 0 nsec > fn:PASS:access(/sys/kernel/debug/fs1/b) 0 nsec > bpf_testmod.ko is already unloaded. > Loading bpf_testmod.ko... > Successfully loaded bpf_testmod.ko. > test_test_bpffs:PASS:clone 0 nsec > test_test_bpffs:PASS:waitpid 0 nsec > test_test_bpffs:PASS:bpffs test 0 nsec > #282 test_bpffs:OK > Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED > Successfully unloaded bpf_testmod.ko. > > [0] https://github.com/danobi/vmtest > > Signed-off-by: Manu Bretelle > --- > .../selftests/bpf/prog_tests/test_bpffs.c | 28 +++++++++++++++++++ > 1 file changed, 28 insertions(+) > > diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c > index 214d9f4a94a5..001bf694c269 100644 > --- a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c > +++ b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c > @@ -3,12 +3,14 @@ > #define _GNU_SOURCE > #include > #include > +#include > #include > #include > #include > #include > > #define TDIR "/sys/kernel/debug" > +#define MTAB "/etc/mtab" > > static int read_iter(char *file) > { > @@ -32,6 +34,8 @@ static int read_iter(char *file) > > static int fn(void) > { > + /* A buffer to store logging messages */ > + char buf[1024]; > struct stat a, b, c; > int err, map; > > @@ -43,6 +47,30 @@ static int fn(void) > if (!ASSERT_OK(err, "mount /")) > goto out; > > + /* TDIR may have mounts below. unount them first */ > + FILE *mtab = setmntent(MTAB, "r"); > + > + if (!ASSERT_TRUE(mtab != NULL, "accessing " MTAB)) { > + err = errno; > + goto out; > + } > + > + struct mntent *mnt = NULL; > + > + while ((mnt = getmntent(mtab)) != NULL) { > + if (strlen(mnt->mnt_dir) > strlen(TDIR) && > + strncmp(TDIR, mnt->mnt_dir, strlen(TDIR)) == 0) { > + snprintf(buf, sizeof(buf) - 1, "umount %s", mnt->mnt_dir); > + err = umount(mnt->mnt_dir); > + if (!ASSERT_OK(err, buf)) { > + endmntent(mtab); > + goto out; > + } > + } > + } > + // Ignore any error here > + endmntent(mtab); > + > err = umount(TDIR); > if (!ASSERT_OK(err, "umount " TDIR)) > goto out;