The patch titled Subject: selftests/mm:fix test_prctl_fork_exec return failure has been added to the -mm mm-hotfixes-unstable branch. Its filename is selftests-mm-fix-test_prctl_fork_exec-return-failure.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: aigourensheng shechenglong001@gmail.com Subject: selftests/mm:fix test_prctl_fork_exec return failure Date: Mon, 17 Jun 2024 01:29:34 -0400

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 ---

tools/testing/selftests/mm/ksm_functional_tests.c | 38 ++++++------ 1 file changed, 22 insertions(+), 16 deletions(-)

--- a/tools/testing/selftests/mm/ksm_functional_tests.c~selftests-mm-fix-test_prctl_fork_exec-return-failure +++ a/tools/testing/selftests/mm/ksm_functional_tests.c @@ -656,12 +656,33 @@ unmap: munmap(map, size); }

+static void init_global_file_handles(void) +{ + mem_fd = open("/proc/self/mem", O_RDWR); + if (mem_fd < 0) + ksft_exit_fail_msg("opening /proc/self/mem failed\n"); + ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR); + if (ksm_fd < 0) + ksft_exit_skip("open("/sys/kernel/mm/ksm/run") failed\n"); + ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY); + if (ksm_full_scans_fd < 0) + ksft_exit_skip("open("/sys/kernel/mm/ksm/full_scans") failed\n"); + pagemap_fd = open("/proc/self/pagemap", O_RDONLY); + if (pagemap_fd < 0) + 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); + 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()); }

@@ -674,22 +695,7 @@ int main(int argc, char **argv)

pagesize = getpagesize();

- mem_fd = open("/proc/self/mem", O_RDWR); - if (mem_fd < 0) - ksft_exit_fail_msg("opening /proc/self/mem failed\n"); - ksm_fd = open("/sys/kernel/mm/ksm/run", O_RDWR); - if (ksm_fd < 0) - ksft_exit_skip("open("/sys/kernel/mm/ksm/run") failed\n"); - ksm_full_scans_fd = open("/sys/kernel/mm/ksm/full_scans", O_RDONLY); - if (ksm_full_scans_fd < 0) - ksft_exit_skip("open("/sys/kernel/mm/ksm/full_scans") failed\n"); - pagemap_fd = open("/proc/self/pagemap", O_RDONLY); - if (pagemap_fd < 0) - 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); - ksm_use_zero_pages_fd = open("/sys/kernel/mm/ksm/use_zero_pages", O_RDWR); + init_global_file_handles();

test_unmerge(); test_unmerge_zero_pages(); _

Patches currently in -mm which might be from shechenglong001@gmail.com are

selftests-mm-fix-test_prctl_fork_exec-return-failure.patch