6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Edward Liaw <edliaw@xxxxxxxxxx> commit 5bb1f4c9340e01003b00b94d539eadb0da88f48e upstream. Patch series "selftests/mm: revert pthread_barrier change" On Android arm, pthread_create followed by a fork caused a deadlock in the case where the fork required work to be completed by the created thread. The previous patches incorrectly assumed that the parent would always initialize the pthread_barrier for the child thread. This reverts the change and replaces the fix for wp-fork-with-event with the original use of atomic_bool. This patch (of 3): This reverts commit e142cc87ac4ec618f2ccf5f68aedcd6e28a59d9d. fork_event_consumer may be called by other tests that do not initialize the pthread_barrier, so this approach is not correct. The subsequent patch will revert to using atomic_bool instead. Link: https://lkml.kernel.org/r/20241018171734.2315053-1-edliaw@xxxxxxxxxx Link: https://lkml.kernel.org/r/20241018171734.2315053-2-edliaw@xxxxxxxxxx Fixes: e142cc87ac4e ("fix deadlock for fork after pthread_create on ARM") Signed-off-by: Edward Liaw <edliaw@xxxxxxxxxx> Cc: Ryan Roberts <ryan.roberts@xxxxxxx> Cc: Peter Xu <peterx@xxxxxxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/mm/uffd-unit-tests.c | 7 ------- 1 file changed, 7 deletions(-) --- a/tools/testing/selftests/mm/uffd-unit-tests.c +++ b/tools/testing/selftests/mm/uffd-unit-tests.c @@ -237,9 +237,6 @@ static void *fork_event_consumer(void *d fork_event_args *args = data; struct uffd_msg msg = { 0 }; - /* Ready for parent thread to fork */ - pthread_barrier_wait(&ready_for_fork); - /* Read until a full msg received */ while (uffd_read_msg(args->parent_uffd, &msg)); @@ -307,12 +304,8 @@ static int pagemap_test_fork(int uffd, b /* Prepare a thread to resolve EVENT_FORK */ if (with_event) { - pthread_barrier_init(&ready_for_fork, NULL, 2); if (pthread_create(&thread, NULL, fork_event_consumer, &args)) err("pthread_create()"); - /* Wait for child thread to start before forking */ - pthread_barrier_wait(&ready_for_fork); - pthread_barrier_destroy(&ready_for_fork); } child = fork();
