FAILED: patch "[PATCH] selftests/mm:fix test_prctl_fork_exec return failure" failed to apply to 6.9-stable tree

The patch below does not apply to the 6.9-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.9.y
git checkout FETCH_HEAD
git cherry-pick -x 8b8546d298dc9ce9d5d01a06c822e255d2159ca7
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024070135-poster-twirl-bd75@gregkh' --subject-prefix 'PATCH 6.9.y' HEAD^..

Possible dependencies:

8b8546d298dc ("selftests/mm:fix test_prctl_fork_exec return failure") 6c47de3be3a0 ("selftest/mm: ksm_functional_tests: extend test case for ksm fork/exec")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8b8546d298dc9ce9d5d01a06c822e255d2159ca7 Mon Sep 17 00:00:00 2001
From: aigourensheng <[email protected]>
Date: Mon, 17 Jun 2024 01:29:34 -0400
Subject: [PATCH] selftests/mm:fix test_prctl_fork_exec return failure

After calling fork() in test_prctl_fork_exec(), the global variable ksm_full_scans_fd is initialized to 0 in the child process upon entering the main function of ./ksm_functional_tests.

In the function call chain test_child_ksm() -> __mmap_and_merge_range -> ksm_merge-> ksm_get_full_scans, start_scans = ksm_get_full_scans() will return an error. Therefore, the value of ksm_full_scans_fd needs to be initialized before calling test_child_ksm in the child process.

index 37de82da9be7..b61803e36d1c 100644
@@ -656,24 +656,8 @@ static void test_prot_none(void)
 	munmap(map, size);
 }
 
-int main(int argc, char **argv)
+static void init_global_file_handles(void)
 {
-	unsigned int tests = 8;
-	int err;
-
-	if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
-		exit(test_child_ksm());
-	}
-
-#ifdef __NR_userfaultfd
-	tests++;
-#endif
-
-	ksft_print_header();
-	ksft_set_plan(tests);
-
-	pagesize = getpagesize();
-
 	mem_fd = open("/proc/self/mem", O_RDWR);
 	if (mem_fd < 0)
 		ksft_exit_fail_msg("opening /proc/self/mem failed\n");

@@ -688,8 +672,30 @@ int main(int argc, char **argv)
 		ksft_exit_skip("open(\"/proc/self/pagemap\") failed\n");
 	proc_self_ksm_stat_fd = open("/proc/self/ksm_stat", O_RDONLY);
 	proc_self_ksm_merging_pages_fd = open("/proc/self/ksm_merging_pages",
-					      O_RDONLY);
+						O_RDONLY);
 	ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR);
+}
+
+int main(int argc, char **argv)
+{
+	unsigned int tests = 8;
+	int err;
+
+	if (argc > 1 && !strcmp(argv[1], FORK_EXEC_CHILD_PRG_NAME)) {
+		init_global_file_handles();
+		exit(test_child_ksm());
+	}
+
+#ifdef __NR_userfaultfd
+	tests++;
+#endif
+
+	ksft_print_header();
+	ksft_set_plan(tests);
+
+	pagesize = getpagesize();
+
+	init_global_file_handles();
 
 	test_unmerge();
 	test_unmerge_zero_pages();