Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Ingo Molnar:

 - Apply a number of membarrier related fixes and cleanups, which fixes
   a use-after-free race in the membarrier code

 - Introduce proper RCU protection for tasks on the runqueue - to get
   rid of the subtle task_rcu_dereference() interface that was easy to
   get wrong

 - Misc fixes, but also an EAS speedup

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Avoid redundant EAS calculation
  sched/core: Remove double update_max_interval() call on CPU startup
  sched/core: Fix preempt_schedule() interrupt return comment
  sched/fair: Fix -Wunused-but-set-variable warnings
  sched/core: Fix migration to invalid CPU in __set_cpus_allowed_ptr()
  sched/membarrier: Return -ENOMEM to userspace on memory allocation failure
  sched/membarrier: Skip IPIs when mm->mm_users == 1
  selftests, sched/membarrier: Add multi-threaded test
  sched/membarrier: Fix p->mm->membarrier_state racy load
  sched/membarrier: Call sync_core only before usermode for same mm
  sched/membarrier: Remove redundant check
  sched/membarrier: Fix private expedited registration check
  tasks, sched/core: RCUify the assignment of rq->curr
  tasks, sched/core: With a grace period after finish_task_switch(), remove unnecessary code
  tasks, sched/core: Ensure tasks are available for a grace period after leaving the runqueue
  tasks: Add a count of task RCU users
  sched/core: Convert vcpu_is_preempted() from macro to an inline function
  sched/fair: Remove unused cfs_rq_clock_task() function

5 files changed, 124 insertions, 21 deletions

diff --git a/tools/testing/selftests/membarrier/.gitignore b/tools/testing/selftests/membarrier/.gitignore
index 020c44f49a9e..f2f7ec0a99b4 100644
--- a/tools/testing/selftests/membarrier/.gitignore
+++ b/tools/testing/selftests/membarrier/.gitignore
@@ -1 +1,2 @@
-membarrier_test
+membarrier_test_multi_thread
+membarrier_test_single_thread
diff --git a/tools/testing/selftests/membarrier/Makefile b/tools/testing/selftests/membarrier/Makefile
index 97e3bdf3d1e9..34d1c81a2324 100644
--- a/tools/testing/selftests/membarrier/Makefile
+++ b/tools/testing/selftests/membarrier/Makefile
@@ -1,7 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0-only
 CFLAGS += -g -I../../../../usr/include/
+LDLIBS += -lpthread
 
-TEST_GEN_PROGS := membarrier_test
+TEST_GEN_PROGS := membarrier_test_single_thread \
+		membarrier_test_multi_thread
 
 include ../lib.mk
-
diff --git a/tools/testing/selftests/membarrier/membarrier_test.c b/tools/testing/selftests/membarrier/membarrier_test_impl.h
index 70b4ddbf126b..186be69f0a59 100644
--- a/tools/testing/selftests/membarrier/membarrier_test.c
+++ b/tools/testing/selftests/membarrier/membarrier_test_impl.h
@@ -1,10 +1,11 @@
-// SPDX-License-Identifier: GPL-2.0
+/* SPDX-License-Identifier: GPL-2.0 */
 #define _GNU_SOURCE
 #include <linux/membarrier.h>
 #include <syscall.h>
 #include <stdio.h>
 #include <errno.h>
 #include <string.h>
+#include <pthread.h>
 
 #include "../kselftest.h"
 
@@ -223,7 +224,7 @@ static int test_membarrier_global_expedited_success(void)
 	return 0;
 }
 
-static int test_membarrier(void)
+static int test_membarrier_fail(void)
 {
 	int status;
 
@@ -233,10 +234,27 @@ static int test_membarrier(void)
 	status = test_membarrier_flags_fail();
 	if (status)
 		return status;
-	status = test_membarrier_global_success();
+	status = test_membarrier_private_expedited_fail();
 	if (status)
 		return status;
-	status = test_membarrier_private_expedited_fail();
+	status = sys_membarrier(MEMBARRIER_CMD_QUERY, 0);
+	if (status < 0) {
+		ksft_test_result_fail("sys_membarrier() failed\n");
+		return status;
+	}
+	if (status & MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE) {
+		status = test_membarrier_private_expedited_sync_core_fail();
+		if (status)
+			return status;
+	}
+	return 0;
+}
+
+static int test_membarrier_success(void)
+{
+	int status;
+
+	status = test_membarrier_global_success();
 	if (status)
 		return status;
 	status = test_membarrier_register_private_expedited_success();
@@ -251,9 +269,6 @@ static int test_membarrier(void)
 		return status;
 	}
 	if (status & MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE) {
-		status = test_membarrier_private_expedited_sync_core_fail();
-		if (status)
-			return status;
 		status = test_membarrier_register_private_expedited_sync_core_success();
 		if (status)
 			return status;
@@ -300,14 +315,3 @@ static int test_membarrier_query(void)
 	ksft_test_result_pass("sys_membarrier available\n");
 	return 0;
 }
-
-int main(int argc, char **argv)
-{
-	ksft_print_header();
-	ksft_set_plan(13);
-
-	test_membarrier_query();
-	test_membarrier();
-
-	return ksft_exit_pass();
-}
diff --git a/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c b/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c
new file mode 100644
index 000000000000..ac5613e5b0eb
--- /dev/null
+++ b/tools/testing/selftests/membarrier/membarrier_test_multi_thread.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <linux/membarrier.h>
+#include <syscall.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <pthread.h>
+
+#include "membarrier_test_impl.h"
+
+static int thread_ready, thread_quit;
+static pthread_mutex_t test_membarrier_thread_mutex =
+	PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t test_membarrier_thread_cond =
+	PTHREAD_COND_INITIALIZER;
+
+void *test_membarrier_thread(void *arg)
+{
+	pthread_mutex_lock(&test_membarrier_thread_mutex);
+	thread_ready = 1;
+	pthread_cond_broadcast(&test_membarrier_thread_cond);
+	pthread_mutex_unlock(&test_membarrier_thread_mutex);
+
+	pthread_mutex_lock(&test_membarrier_thread_mutex);
+	while (!thread_quit)
+		pthread_cond_wait(&test_membarrier_thread_cond,
+				  &test_membarrier_thread_mutex);
+	pthread_mutex_unlock(&test_membarrier_thread_mutex);
+
+	return NULL;
+}
+
+static int test_mt_membarrier(void)
+{
+	int i;
+	pthread_t test_thread;
+
+	pthread_create(&test_thread, NULL,
+		       test_membarrier_thread, NULL);
+
+	pthread_mutex_lock(&test_membarrier_thread_mutex);
+	while (!thread_ready)
+		pthread_cond_wait(&test_membarrier_thread_cond,
+				  &test_membarrier_thread_mutex);
+	pthread_mutex_unlock(&test_membarrier_thread_mutex);
+
+	test_membarrier_fail();
+
+	test_membarrier_success();
+
+	pthread_mutex_lock(&test_membarrier_thread_mutex);
+	thread_quit = 1;
+	pthread_cond_broadcast(&test_membarrier_thread_cond);
+	pthread_mutex_unlock(&test_membarrier_thread_mutex);
+
+	pthread_join(test_thread, NULL);
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	ksft_print_header();
+	ksft_set_plan(13);
+
+	test_membarrier_query();
+
+	/* Multi-threaded */
+	test_mt_membarrier();
+
+	return ksft_exit_pass();
+}
diff --git a/tools/testing/selftests/membarrier/membarrier_test_single_thread.c b/tools/testing/selftests/membarrier/membarrier_test_single_thread.c
new file mode 100644
index 000000000000..c1c963902854
--- /dev/null
+++ b/tools/testing/selftests/membarrier/membarrier_test_single_thread.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+#include <linux/membarrier.h>
+#include <syscall.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <pthread.h>
+
+#include "membarrier_test_impl.h"
+
+int main(int argc, char **argv)
+{
+	ksft_print_header();
+	ksft_set_plan(13);
+
+	test_membarrier_query();
+
+	test_membarrier_fail();
+
+	test_membarrier_success();
+
+	return ksft_exit_pass();
+}