Some additional synchronization is needed on Android ARM64; we see a deadlock with pthread_create when the parent thread races forward before the child has a chance to start doing work.
Fixes: cff294582798 ("selftests/mm: extend and rename uffd pagemap test") CC: Ryan Roberts ryan.roberts@arm.com Signed-off-by: Edward Liaw edliaw@google.com --- tools/testing/selftests/mm/uffd-unit-tests.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c index b3d21eed203d..a2e71b1636e7 100644 --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -241,6 +241,8 @@ static void *fork_event_consumer(void *data) fork_event_args *args = data; struct uffd_msg msg = { 0 };
+ ready_for_fork = true; + /* Read until a full msg received */ while (uffd_read_msg(args->parent_uffd, &msg));
@@ -308,8 +310,11 @@ static int pagemap_test_fork(int uffd, bool with_event, bool test_pin)
/* Prepare a thread to resolve EVENT_FORK */ if (with_event) { + ready_for_fork = false; if (pthread_create(&thread, NULL, fork_event_consumer, &args)) err("pthread_create()"); + while (!ready_for_fork) + ; /* Wait for the poll_thread to start executing before forking */ }
child = fork();