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authorEdward Liaw <edliaw@google.com>2024-03-25 19:40:52 +0000
committerTreehugger Robot <android-test-infra-autosubmit@system.gserviceaccount.com>2024-04-24 16:37:15 +0000
commit541cfce197d022011f1b848ad24889ed12d2fc2c (patch)
treed77ff07574fe7f97071084a6ec398a61b2a184ec
parent8af81c4b21ffd7658facdc0395aafb1000a48267 (diff)
downloadcommon-541cfce197d022011f1b848ad24889ed12d2fc2c.tar.gz
UPSTREAM: selftests/mm: fix ARM related issue with fork after pthread_create
Following issue was observed while running the uffd-unit-tests selftest on ARM devices. On x86_64 no issues were detected: pthread_create followed by fork caused deadlock in certain cases wherein fork required some work to be completed by the created thread. Used synchronization to ensure that created thread's start function has started before invoking fork. [edliaw@google.com: refactored to use atomic_bool] Link: https://lkml.kernel.org/r/20240325194100.775052-1-edliaw@google.com Fixes: 760aee0b71e3 ("selftests/mm: add tests for RO pinning vs fork()") Change-Id: I26931be093babe33aee70e0c8fbfd532255d74a3 Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Signed-off-by: Edward Liaw <edliaw@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> (cherry picked from commit 8c864371b2a15a23ce35aa7e2bd241baaad6fbe8) Signed-off-by: Edward Liaw <edliaw@google.com>
-rw-r--r--tools/testing/selftests/mm/uffd-common.c3
-rw-r--r--tools/testing/selftests/mm/uffd-common.h2
-rw-r--r--tools/testing/selftests/mm/uffd-unit-tests.c10
3 files changed, 15 insertions, 0 deletions
diff --git a/tools/testing/selftests/mm/uffd-common.c b/tools/testing/selftests/mm/uffd-common.c
index b0ac0ec2356d..7ad6ba660c7d 100644
--- a/tools/testing/selftests/mm/uffd-common.c
+++ b/tools/testing/selftests/mm/uffd-common.c
@@ -18,6 +18,7 @@ bool test_uffdio_wp = true;
unsigned long long *count_verify;
uffd_test_ops_t *uffd_test_ops;
uffd_test_case_ops_t *uffd_test_case_ops;
+atomic_bool ready_for_fork;
static int uffd_mem_fd_create(off_t mem_size, bool hugetlb)
{
@@ -518,6 +519,8 @@ void *uffd_poll_thread(void *arg)
pollfd[1].fd = pipefd[cpu*2];
pollfd[1].events = POLLIN;
+ ready_for_fork = true;
+
for (;;) {
ret = poll(pollfd, 2, -1);
if (ret <= 0) {
diff --git a/tools/testing/selftests/mm/uffd-common.h b/tools/testing/selftests/mm/uffd-common.h
index cb055282c89c..cc5629c3d2aa 100644
--- a/tools/testing/selftests/mm/uffd-common.h
+++ b/tools/testing/selftests/mm/uffd-common.h
@@ -32,6 +32,7 @@
#include <inttypes.h>
#include <stdint.h>
#include <sys/random.h>
+#include <stdatomic.h>
#include "../kselftest.h"
#include "vm_util.h"
@@ -103,6 +104,7 @@ extern bool map_shared;
extern bool test_uffdio_wp;
extern unsigned long long *count_verify;
extern volatile bool test_uffdio_copy_eexist;
+extern atomic_bool ready_for_fork;
extern uffd_test_ops_t anon_uffd_test_ops;
extern uffd_test_ops_t shmem_uffd_test_ops;
diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 536e09b03aee..21ec23206ab4 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -775,6 +775,8 @@ static void uffd_sigbus_test_common(bool wp)
char c;
struct uffd_args args = { 0 };
+ ready_for_fork = false;
+
fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
if (uffd_register(uffd, area_dst, nr_pages * page_size,
@@ -790,6 +792,9 @@ static void uffd_sigbus_test_common(bool wp)
if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
err("uffd_poll_thread create");
+ while (!ready_for_fork)
+ ; /* Wait for the poll_thread to start executing before forking */
+
pid = fork();
if (pid < 0)
err("fork");
@@ -829,6 +834,8 @@ static void uffd_events_test_common(bool wp)
char c;
struct uffd_args args = { 0 };
+ ready_for_fork = false;
+
fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK);
if (uffd_register(uffd, area_dst, nr_pages * page_size,
true, wp, false))
@@ -838,6 +845,9 @@ static void uffd_events_test_common(bool wp)
if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args))
err("uffd_poll_thread create");
+ while (!ready_for_fork)
+ ; /* Wait for the poll_thread to start executing before forking */
+
pid = fork();
if (pid < 0)
err("fork");