The patch below does not apply to the 6.6-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 stable@vger.kernel.org.

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-6.6.y git checkout FETCH_HEAD git cherry-pick -x 8b8546d298dc9ce9d5d01a06c822e255d2159ca7 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024070135-gave-hatchback-24d5@gregkh' --subject-prefix 'PATCH 6.6.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") 0374af1da077 ("mm/ksm: test case for prctl fork/exec workflow")

thanks,

greg k-h

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

From 8b8546d298dc9ce9d5d01a06c822e255d2159ca7 Mon Sep 17 00:00:00 2001 From: aigourensheng shechenglong001@gmail.com 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.

Link: https://lkml.kernel.org/r/20240617052934.5834-1-shechenglong001@gmail.com Signed-off-by: aigourensheng shechenglong001@gmail.com Acked-by: David Hildenbrand david@redhat.com Cc: Shuah Khan shuah@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/tools/testing/selftests/mm/ksm_functional_tests.c b/tools/testing/selftests/mm/ksm_functional_tests.c index 37de82da9be7..b61803e36d1c 100644 --- a/tools/testing/selftests/mm/ksm_functional_tests.c +++ b/tools/testing/selftests/mm/ksm_functional_tests.c @@ -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();