Commit f2330b65 authored by Edward Liaw's avatar Edward Liaw Committed by Andrew Morton
Browse files

selftests/mm: fix deadlock for fork after pthread_create with atomic_bool 

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.

Link: https://lkml.kernel.org/r/20241018171734.2315053-4-edliaw@google.com


Fixes: cff29458 ("selftests/mm: extend and rename uffd pagemap test")
Signed-off-by: default avatarEdward Liaw <edliaw@google.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3673167a

tools/testing/selftests/mm/uffd-unit-tests.c

+5 −0
Original line number Diff line number Diff line
@@ -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();