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selftests/mm: fix deadlock for fork after pthread_create on ARM

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On Android with arm, there is some synchronization needed to avoid a
deadlock when forking after pthread_create.

Link: https://lkml.kernel.org/r/20241003211716.371786-3-edliaw@google.com
Fixes: cff2945827 ("selftests/mm: extend and rename uffd pagemap test")
Signed-off-by: Edward Liaw <edliaw@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Edward Liaw 2024-10-03 21:17:11 +00:00 committed by Andrew Morton
parent e61ef21e27
commit e142cc87ac
1 changed files with 7 additions and 0 deletions
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7
tools/testing/selftests/mm/uffd-unit-tests.c
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@ -241,6 +241,9 @@ static void *fork_event_consumer(void *data)
fork_event_args *args = data; fork_event_args *args = data;
struct uffd_msg msg = { 0 }; struct uffd_msg msg = { 0 };
/* Ready for parent thread to fork */
pthread_barrier_wait(&ready_for_fork);
/* Read until a full msg received */ /* Read until a full msg received */
while (uffd_read_msg(args->parent_uffd, &msg)); while (uffd_read_msg(args->parent_uffd, &msg));
@ -308,8 +311,12 @@ static int pagemap_test_fork(int uffd, bool with_event, bool test_pin)
/* Prepare a thread to resolve EVENT_FORK */ /* Prepare a thread to resolve EVENT_FORK */
if (with_event) { if (with_event) {
pthread_barrier_init(&ready_for_fork, NULL, 2);
if (pthread_create(&thread, NULL, fork_event_consumer, &args)) if (pthread_create(&thread, NULL, fork_event_consumer, &args))
err("pthread_create()"); 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(); child = fork();