BACKPORT: selftests/mm: call uffd_test_ctx_clear at the end of the test

uffd_test_ctx_clear() is being called from uffd_test_ctx_init() to unmap
areas used in the previous test run.  This approach is problematic because
while unmapping areas uffd_test_ctx_clear() uses page_size and nr_pages
which might differ from one test run to another.  Fix this by calling
uffd_test_ctx_clear() after each test is done.

Link: https://lkml.kernel.org/r/20231206103702.3873743-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Axel Rasmussen <axelrasmussen@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Nicolas Geoffray <ngeoffray@google.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: ZhangPeng <zhangpeng362@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 1c8d39fa7b63dcbb77af7b0325fdc519c35fe618)
Conflicts:
	tools/testing/selftests/mm/uffd-common.c
	tools/testing/selftests/mm/uffd-common.h
	tools/testing/selftests/mm/uffd-stress.c
	tools/testing/selftests/mm/uffd-unit-tests.c
	tools/testing/selftests/vm/userfaultfd.c

1. Userfaultfd selftest was split into separate files and as a consequence
   the code moved from selftests/vm/userfaultfd.c to selftests/mm/uffd_* files.

Bug: 274911254
Change-Id: Ic224c3965a645342dc0f41e743d3c072b7bb852e
Signed-off-by: Lokesh Gidra <lokeshgidra@google.com>

tools/testing/selftests/vm/userfaultfd.c

@@ -517,8 +517,6 @@ static void uffd_test_ctx_init(uint64_t features)
 {
 	unsigned long nr, cpu;
 
-	uffd_test_ctx_clear();
-
 	uffd_test_ops->allocate_area((void **)&area_src, true);
 	uffd_test_ops->allocate_area((void **)&area_dst, false);
 
@@ -1195,6 +1193,7 @@ static int userfaultfd_zeropage_test(void)
 		if (my_bcmp(area_dst, zeropage, page_size))
 			err("zeropage is not zero");
 
+	uffd_test_ctx_clear();
 	printf("done.\n");
 	return 0;
 }
@@ -1207,6 +1206,7 @@ static int userfaultfd_events_test(void)
 	pid_t pid;
 	char c;
 	struct uffd_stats stats = { 0 };
+	int ret;
 
 	printf("testing events (fork, remap, remove): ");
 	fflush(stdout);
@@ -1243,12 +1243,16 @@ static int userfaultfd_events_test(void)
 		err("faulting process failed");
 	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
 		err("pipe write");
+	ret = 1;
 	if (pthread_join(uffd_mon, NULL))
-		return 1;
+		goto out;
 
 	uffd_stats_report(&stats, 1);
 
-	return stats.missing_faults != nr_pages;
+	ret = stats.missing_faults != nr_pages;
+out:
+	uffd_test_ctx_clear();
+	return ret;
 }
 
 static int userfaultfd_sig_test(void)
@@ -1260,6 +1264,7 @@ static int userfaultfd_sig_test(void)
 	pid_t pid;
 	char c;
 	struct uffd_stats stats = { 0 };
+	int ret;
 
 	printf("testing signal delivery: ");
 	fflush(stdout);
@@ -1300,14 +1305,18 @@ static int userfaultfd_sig_test(void)
 		err("faulting process failed");
 	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
 		err("pipe write");
+	ret = 1;
 	if (pthread_join(uffd_mon, (void **)&userfaults))
-		return 1;
+		goto out;
 
 	printf("done.\n");
 	if (userfaults)
 		err("Signal test failed, userfaults: %ld", userfaults);
 
-	return userfaults != 0;
+	ret = userfaults != 0;
+out:
+	uffd_test_ctx_clear();
+	return ret;
 }
 
 void check_memory_contents(char *p)
@@ -1336,6 +1345,7 @@ static int userfaultfd_minor_test(void)
 	pthread_t uffd_mon;
 	char c;
 	struct uffd_stats stats = { 0 };
+	int ret;
 
 	if (!test_uffdio_minor)
 		return 0;
@@ -1376,8 +1386,9 @@ static int userfaultfd_minor_test(void)
 
 	if (write(pipefd[1], &c, sizeof(c)) != sizeof(c))
 		err("pipe write");
+	ret = 1;
 	if (pthread_join(uffd_mon, NULL))
-		return 1;
+		goto out;
 
 	uffd_stats_report(&stats, 1);
 
@@ -1398,7 +1409,10 @@ static int userfaultfd_minor_test(void)
 		printf(" done.\n");
 	}
 
-	return stats.missing_faults != 0 || stats.minor_faults != nr_pages;
+	ret = stats.missing_faults != 0 || stats.minor_faults != nr_pages;
+out:
+	uffd_test_ctx_clear();
+	return ret;
 }
 
 #define BIT_ULL(nr)                   (1ULL << (nr))
@@ -1532,6 +1546,7 @@ static void userfaultfd_pagemap_test(unsigned int test_pgsize)
 	pagemap_check_wp(value, false);
 
 	close(pagemap_fd);
+	uffd_test_ctx_clear();
 	printf("done\n");
 }
 
@@ -1621,8 +1636,10 @@ static int userfaultfd_stress(void)
 		uffd_stats_reset(uffd_stats, nr_cpus);
 
 		/* bounce pass */
-		if (stress(uffd_stats))
+		if (stress(uffd_stats)) {
+			uffd_test_ctx_clear();
 			return 1;
+		}
 
 		/* Clear all the write protections if there is any */
 		if (test_uffdio_wp)
@@ -1654,6 +1671,7 @@ static int userfaultfd_stress(void)
 
 		uffd_stats_report(uffd_stats, nr_cpus);
 	}
+	uffd_test_ctx_clear();
 
 	if (test_type == TEST_ANON) {
 		/*