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@xxxxxxx>
Signed-off-by: Edward Liaw <edliaw@xxxxxxxxxx>
---
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();
--
2.47.0.105.g07ac214952-goog
