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[188.155.177.222]) by smtp.gmail.com with ESMTPSA id n4sm8084256eja.121.2021.06.29.05.10.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Jun 2021 05:10:55 -0700 (PDT) From: Krzysztof Kozlowski To: ltp@lists.linux.it Date: Tue, 29 Jun 2021 14:10:45 +0200 Message-Id: <20210629121047.100391-3-krzysztof.kozlowski@canonical.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210629121047.100391-1-krzysztof.kozlowski@canonical.com> References: <20210629121047.100391-1-krzysztof.kozlowski@canonical.com> MIME-Version: 1.0 X-Virus-Scanned: clamav-milter 0.102.4 at in-3.smtp.seeweb.it X-Virus-Status: Clean X-Spam-Status: No, score=0.0 required=7.0 tests=SPF_HELO_NONE,SPF_NONE autolearn=disabled version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on in-3.smtp.seeweb.it Subject: [LTP] [PATCH v4 2/4] tst_pid.c: fix fork failure on small memory systems X-BeenThere: ltp@lists.linux.it X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux Test Project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: ltp-bounces+incoming=patchwork.ozlabs.org@lists.linux.it Sender: "ltp" Running syscalls/msgstress04 on a system with less than ~4 GB of RAM fails: Fork failure in the first child of child group 4396 Fork failure in the second child of child group 4413 msgstress04 1 TFAIL : msgstress04.c:222: Child exit status = 1 The reason is cgroups pid limit set by systemd user.slice. The limit is set for login session, also for root user. For example on 2 GB RAM machine it is set as: /sys/fs/cgroup/pids/user.slice/user-0.slice/pids.max:5207 Read the maximum number of pids and adjust the test limit. Signed-off-by: Krzysztof Kozlowski --- include/tst_pid.h | 4 ++- lib/tst_pid.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 72 insertions(+), 2 deletions(-) diff --git a/include/tst_pid.h b/include/tst_pid.h index 6c42f73a57e7..8d999a655f1a 100644 --- a/include/tst_pid.h +++ b/include/tst_pid.h @@ -14,7 +14,9 @@ pid_t tst_get_unused_pid_(void (*cleanup_fn)(void)); /* * Returns number of free pids by subtraction of the number of pids - * currently used ('ps -eT') from max_pids + * currently used ('ps -eT') from maximum number of processes. + * The limit of processes come from kernel pid_max and cgroup session limits + * (e.g. configured by systemd user.slice). */ int tst_get_free_pids_(void (*cleanup_fn)(void)); diff --git a/lib/tst_pid.c b/lib/tst_pid.c index 9568cc9e91d2..c408172675a7 100644 --- a/lib/tst_pid.c +++ b/lib/tst_pid.c @@ -18,14 +18,20 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ +#include #include #include +#include +#include #include +#include #include "test.h" #include "tst_pid.h" #include "old_safe_file_ops.h" #define PID_MAX_PATH "/proc/sys/kernel/pid_max" +#define CGROUPS_V1_SLICE_FMT "/sys/fs/cgroup/pids/user.slice/user-%d.slice/pids.max" +#define CGROUPS_V2_SLICE_FMT "/sys/fs/cgroup/user.slice/user-%d.slice/pids.max" pid_t tst_get_unused_pid_(void (*cleanup_fn) (void)) { @@ -36,10 +42,68 @@ pid_t tst_get_unused_pid_(void (*cleanup_fn) (void)) return pid; } +/* + * Get the effective session UID - either one invoking current test via sudo + * or the real UID. + */ +static unsigned int get_session_uid(void) +{ + const char *sudo_uid; + + sudo_uid = getenv("SUDO_UID"); + if (sudo_uid) { + unsigned int real_uid; + int ret; + + ret = sscanf(sudo_uid, "%u", &real_uid); + if (ret == 1) + return real_uid; + } + + return getuid(); +} + +static int read_session_pids_limit(const char *path_fmt, int uid, + void (*cleanup_fn) (void)) +{ + int max_pids, ret; + char path[PATH_MAX]; + + ret = snprintf(path, sizeof(path), path_fmt, uid); + if (ret < 0 || (size_t)ret >= sizeof(path)) + return -1; + + if (access(path, R_OK) != 0) { + tst_resm(TINFO, "Cannot read session user limits from '%s'", path); + return -1; + } + + SAFE_FILE_SCANF(cleanup_fn, path, "%d", &max_pids); + tst_resm(TINFO, "Found limit of processes %d (from %s)", max_pids, path); + + return max_pids; +} + +static int get_session_pids_limit(void (*cleanup_fn) (void)) +{ + int max_pids, uid; + + uid = get_session_uid(); + max_pids = read_session_pids_limit(CGROUPS_V2_SLICE_FMT, uid, cleanup_fn); + if (max_pids < 0) + max_pids = read_session_pids_limit(CGROUPS_V1_SLICE_FMT, uid, + cleanup_fn); + + if (max_pids < 0) + return -1; + + return max_pids; +} + int tst_get_free_pids_(void (*cleanup_fn) (void)) { FILE *f; - int rc, used_pids, max_pids; + int rc, used_pids, max_pids, max_session_pids; f = popen("ps -eT | wc -l", "r"); if (!f) { @@ -57,6 +121,10 @@ int tst_get_free_pids_(void (*cleanup_fn) (void)) SAFE_FILE_SCANF(cleanup_fn, PID_MAX_PATH, "%d", &max_pids); + max_session_pids = get_session_pids_limit(cleanup_fn); + if ((max_session_pids > 0) && (max_session_pids < max_pids)) + max_pids = max_session_pids; + /* max_pids contains the maximum PID + 1, * used_pids contains used PIDs + 1, * so this additional '1' is eliminated by the substraction */