On Sat, Sep 26, 2026 at 7:42 AM Sebastian Chlad <[email protected]> wrote:
Hi, > test_memcg_inotify_delete_file() and test_memcg_inotify_delete_dir() > wait for IN_DELETE_SELF with a blocking read() on the inotify fd. On a > kernel that does not send IN_DELETE_SELF for kernfs files and > directories, the read() never returns and test_memcontrol hangs until > it is killed by the kselftest timeout. The remaining tests do not run > and no result is reported for the inotify tests. > > Wait for the first event with poll() and a timeout. If IN_DELETE_SELF > does not arrive in time, report it and fail the test instead of > blocking, so that test_memcontrol completes and the remaining results > are reported. But this polls for every read() through read_event(), not just IN_DELETE_SELF. > Assisted-by: claude-opus-5-5 > Signed-off-by: Sebastian Chlad <[email protected]> > --- > .../selftests/cgroup/test_memcontrol.c | 27 ++++++++++++++++--- > 1 file changed, 23 insertions(+), 4 deletions(-) > > diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c > b/tools/testing/selftests/cgroup/test_memcontrol.c > index 0ed82347044e..c00420acc9a1 100644 > --- a/tools/testing/selftests/cgroup/test_memcontrol.c > +++ b/tools/testing/selftests/cgroup/test_memcontrol.c > @@ -11,6 +11,7 @@ > #include <sys/types.h> > #include <unistd.h> > #include <sys/inotify.h> > +#include <poll.h> > #include <sys/socket.h> > #include <sys/wait.h> > #include <arpa/inet.h> > @@ -1655,10 +1656,20 @@ static int test_memcg_oom_group_score_events(const > char *root) > return ret; > } > > +#define INOTIFY_TIMEOUT_MS 5000 > + > static int read_event(int inotify_fd, int expected_event, int expected_wd) > { > + struct pollfd pfd = { .fd = inotify_fd, .events = POLLIN }; > struct inotify_event event; > ssize_t len = 0; > + int ret; > + > + ret = poll(&pfd, 1, INOTIFY_TIMEOUT_MS); > + if (ret == 0) > + return -ETIMEDOUT; This mixes -1 with -ETIMEDOUT. The lack of consistency for error handling is kinda weird. > + if (ret < 0) > + return -1; > > len = read(inotify_fd, &event, sizeof(event)); > if (len < (ssize_t)sizeof(event)) > @@ -1678,7 +1689,7 @@ static int test_memcg_inotify_delete_file(const char > *root) > { > int ret = KSFT_FAIL; > char *memcg = NULL; > - int fd, wd; > + int fd, wd, err; > > memcg = cg_name(root, "memcg_test_0"); > > @@ -1701,7 +1712,11 @@ static int test_memcg_inotify_delete_file(const char > *root) > free(memcg); > memcg = NULL; > > - if (read_event(fd, IN_DELETE_SELF, wd)) > + err = read_event(fd, IN_DELETE_SELF, wd); > + if (err == -ETIMEDOUT) > + fprintf(stderr, "no IN_DELETE_SELF event within %d ms\n", > + INOTIFY_TIMEOUT_MS); > + if (err) > goto cleanup; > > if (read_event(fd, IN_IGNORED, wd)) > @@ -1723,7 +1738,7 @@ static int test_memcg_inotify_delete_dir(const char > *root) > { > int ret = KSFT_FAIL; > char *memcg = NULL; > - int fd, wd; > + int fd, wd, err; > > memcg = cg_name(root, "memcg_test_0"); > > @@ -1746,7 +1761,11 @@ static int test_memcg_inotify_delete_dir(const char > *root) > free(memcg); > memcg = NULL; > > - if (read_event(fd, IN_DELETE_SELF, wd)) > + err = read_event(fd, IN_DELETE_SELF, wd); > + if (err == -ETIMEDOUT) > + fprintf(stderr, "no IN_DELETE_SELF event within %d ms\n", > + INOTIFY_TIMEOUT_MS); > + if (err) > goto cleanup; > > if (read_event(fd, IN_IGNORED, wd)) This IN_IGNORED case now fails silently while IN_DELETE_SELF prints a timeout error message. What about moving the error message up into read_event? That would address the comment about inconsistent return values too.
