selftests/mm: add atexit() and signal handlers to thp_settings

khugepaged registers atexit() and signal handlers that ensure that THP
settings are restored regardless of how the test exited.

Make these handlers available for all users of thp_settings.

The call to thp_save_settings() installs thp_restore_settings as the
atexit() callback and makes sure that signals that kill a process would
still call exit() and atexit() callback.

Update child process in khugepaged tests using thp_settings to use _exit()
instead of exit() to avoid altering THP settings in the middle of a test.

Remove redundant THP cleanup from folio_split_race_test.c.

Link: https://lore.kernel.org/20260511162840.375890-23-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Tested-by: Sarthak Sharma <sarthak.sharma@arm.com>
Tested-by: Luiz Capitulino <luizcap@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam@infradead.org>
Cc: Li Wang <li.wang@linux.dev>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/cow.c b/tools/testing/selftests/mm/cow.c
index d9c69c04b67d8bb61cfb5779a832d1f70a258554..6abdcb30aba8966b5783c4541ef26281efd8d3fc 100644 (file)
--- a/tools/testing/selftests/mm/cow.c
+++ b/tools/testing/selftests/mm/cow.c
@@ -202,7 +202,7 @@ static void do_test_cow_in_parent(char *mem, size_t size, bool do_mprotect,
                log_test_result(KSFT_FAIL);
                goto close_comm_pipes;
        } else if (!ret) {
-               exit(fn(mem, size, &comm_pipes));
+               _exit(fn(mem, size, &comm_pipes));
        }
 
        while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
@@ -333,7 +333,7 @@ static void do_test_vmsplice_in_parent(char *mem, size_t size,
                        ;
                /* Modify page content in the child. */
                memset(mem, 0xff, size);
-               exit(0);
+               _exit(0);
        }
 
        if (!before_fork) {
@@ -480,7 +480,7 @@ static void do_test_iouring(char *mem, size_t size, bool use_fork)
                        write(comm_pipes.child_ready[1], "0", 1);
                        while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
                                ;
-                       exit(0);
+                       _exit(0);
                }
 
                while (read(comm_pipes.child_ready[0], &buf, 1) != 1)
@@ -645,7 +645,7 @@ static void do_test_ro_pin(char *mem, size_t size, enum ro_pin_test test,
                        write(comm_pipes.child_ready[1], "0", 1);
                        while (read(comm_pipes.parent_ready[0], &buf, 1) != 1)
                                ;
-                       exit(0);
+                       _exit(0);
                }
 
                /* Wait until our child is ready. */
@@ -956,7 +956,7 @@ static void do_run_with_thp(test_fn fn, enum thp_run thp_run, size_t thpsize)
                        log_test_result(KSFT_FAIL);
                        goto munmap;
                } else if (!ret) {
-                       exit(0);
+                       _exit(0);
                }
                wait(&ret);
                /* Allow for sharing all pages again. */
@@ -1347,13 +1347,13 @@ static void do_test_anon_thp_collapse(char *mem, size_t size,
                switch (test) {
                case ANON_THP_COLLAPSE_UNSHARED:
                case ANON_THP_COLLAPSE_FULLY_SHARED:
-                       exit(child_memcmp_fn(mem, size, &comm_pipes));
+                       _exit(child_memcmp_fn(mem, size, &comm_pipes));
                        break;
                case ANON_THP_COLLAPSE_LOWER_SHARED:
-                       exit(child_memcmp_fn(mem, size / 2, &comm_pipes));
+                       _exit(child_memcmp_fn(mem, size / 2, &comm_pipes));
                        break;
                case ANON_THP_COLLAPSE_UPPER_SHARED:
-                       exit(child_memcmp_fn(mem + size / 2, size / 2,
+                       _exit(child_memcmp_fn(mem + size / 2, size / 2,
                                             &comm_pipes));
                        break;
                default:
@@ -1911,10 +1911,5 @@ int main(int argc, char **argv)
        run_anon_thp_test_cases();
        run_non_anon_test_cases();
 
-       if (pmdsize) {
-               /* Only if THP is supported. */
-               thp_restore_settings();
-       }
-
        ksft_finished();
 }

diff --git a/tools/testing/selftests/mm/folio_split_race_test.c b/tools/testing/selftests/mm/folio_split_race_test.c
index ff026f183ac7e8eec352922cb5094a6702deedf3..390fd97c1bd99899e7b2ca4ebb1b80d2d7d53154 100644 (file)
--- a/tools/testing/selftests/mm/folio_split_race_test.c
+++ b/tools/testing/selftests/mm/folio_split_race_test.c
@@ -226,23 +226,6 @@ static uint64_t run_iteration(void)
        return reader_failures;
 }
 
-static void thp_cleanup_handler(int signum)
-{
-       thp_restore_settings();
-       /*
-        * Restore default handler and re-raise the signal to exit.
-        * This is to ensure the test process exits with the correct
-        * status code corresponding to the signal.
-        */
-       signal(signum, SIG_DFL);
-       raise(signum);
-}
-
-static void thp_settings_cleanup(void)
-{
-       thp_restore_settings();
-}
-
 int main(void)
 {
        struct thp_settings current_settings;
@@ -261,12 +244,6 @@ int main(void)
                ksft_exit_skip("Please run the test as root\n");
 
        thp_save_settings();
-       /* make sure thp settings are restored */
-       if (atexit(thp_settings_cleanup) != 0)
-               ksft_exit_fail_msg("atexit failed\n");
-
-       signal(SIGINT, thp_cleanup_handler);
-       signal(SIGTERM, thp_cleanup_handler);
 
        thp_read_settings(&current_settings);
        current_settings.shmem_enabled = SHMEM_ADVISE;

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index 61c3b2c4254492a6c16f83df665e4b977f3b27b0..ac2433f19b1e8df506838178c39d4dc8fdefbdd3 100644 (file)
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -80,7 +80,6 @@ struct file_info {
 };
 
 static struct file_info finfo;
-static bool skip_settings_restore;
 static int exit_status;
 
 static void success(const char *msg)
@@ -101,26 +100,6 @@ static void skip(const char *msg)
        exit_status = KSFT_SKIP;
 }
 
-static void restore_settings_atexit(void)
-{
-       if (skip_settings_restore)
-               return;
-
-       ksft_print_msg("Restore THP and khugepaged settings...");
-       thp_restore_settings();
-       success("OK");
-
-       skip_settings_restore = true;
-       ksft_print_cnts();
-       exit(exit_status);
-}
-
-static void restore_settings(int sig)
-{
-       /* exit() will invoke the restore_settings_atexit handler. */
-       exit(sig ? KSFT_FAIL : exit_status);
-}
-
 static void save_settings(void)
 {
        ksft_print_msg("Save THP and khugepaged settings...");
@@ -131,12 +110,6 @@ static void save_settings(void)
        thp_save_settings();
 
        success("OK");
-
-       atexit(restore_settings_atexit);
-       signal(SIGTERM, restore_settings);
-       signal(SIGINT, restore_settings);
-       signal(SIGHUP, restore_settings);
-       signal(SIGQUIT, restore_settings);
 }
 
 static void get_finfo(const char *dir)
@@ -938,8 +911,6 @@ static void collapse_fork(struct collapse_context *c, struct mem_ops *ops)
        ksft_print_msg("Share small page over fork()...");
        if (!fork()) {
                /* Do not touch settings on child exit */
-               skip_settings_restore = true;
-
                if (ops->check_huge(p, 0))
                        success("OK");
                else
@@ -951,7 +922,7 @@ static void collapse_fork(struct collapse_context *c, struct mem_ops *ops)
 
                validate_memory(p, 0, page_size);
                ops->cleanup_area(p, hpage_pmd_size);
-               exit(exit_status);
+               _exit(exit_status);
        }
 
        wait(&wstatus);
@@ -976,8 +947,6 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o
        ksft_print_msg("Share huge page over fork()...");
        if (!fork()) {
                /* Do not touch settings on child exit */
-               skip_settings_restore = true;
-
                if (ops->check_huge(p, 1))
                        success("OK");
                else
@@ -1000,7 +969,7 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o
 
                validate_memory(p, 0, hpage_pmd_size);
                ops->cleanup_area(p, hpage_pmd_size);
-               exit(exit_status);
+               _exit(exit_status);
        }
 
        wait(&wstatus);
@@ -1026,8 +995,6 @@ static void collapse_max_ptes_shared(struct collapse_context *c, struct mem_ops
        ksft_print_msg("Share huge page over fork()...");
        if (!fork()) {
                /* Do not touch settings on child exit */
-               skip_settings_restore = true;
-
                if (ops->check_huge(p, 1))
                        success("OK");
                else
@@ -1060,7 +1027,7 @@ static void collapse_max_ptes_shared(struct collapse_context *c, struct mem_ops
 
                validate_memory(p, 0, hpage_pmd_size);
                ops->cleanup_area(p, hpage_pmd_size);
-               exit(exit_status);
+               _exit(exit_status);
        }
 
        wait(&wstatus);
@@ -1376,5 +1343,5 @@ int main(int argc, char **argv)
                t->fn(t->ctx, t->ops);
        }
 
-       restore_settings(0);
+       ksft_finished();
 }

diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
index e748ebfb3d4e21e7fcf255a4750a517019124884..9bfa5dc4262414cdb435762428aa0802ec6efcaf 100644 (file)
--- a/tools/testing/selftests/mm/thp_settings.c
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <fcntl.h>
 #include <limits.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -15,6 +16,7 @@ static struct thp_settings settings_stack[MAX_SETTINGS_DEPTH];
 static int settings_index;
 static struct thp_settings saved_settings;
 static char dev_queue_read_ahead_path[PATH_MAX];
+static bool thp_settings_saved;
 
 static const char * const thp_enabled_strings[] = {
        "never",
@@ -298,12 +300,35 @@ void thp_pop_settings(void)
 
 void thp_restore_settings(void)
 {
-       thp_write_settings(&saved_settings);
+       if (thp_settings_saved)
+               thp_write_settings(&saved_settings);
+}
+
+static void thp_restore_settings_atexit(void)
+{
+       thp_restore_settings();
+}
+
+static void thp_restore_settings_sighandler(int sig)
+{
+       /* exit() will invoke the thp_restore_settings_atexit handler. */
+       exit(KSFT_FAIL);
 }
 
 void thp_save_settings(void)
 {
        thp_read_settings(&saved_settings);
+       thp_settings_saved = true;
+
+       /*
+        * setup exit hooks to make sure THP settings are restored on graceful
+        * and error exits and signals
+        */
+       atexit(thp_restore_settings_atexit);
+       signal(SIGTERM, thp_restore_settings_sighandler);
+       signal(SIGINT, thp_restore_settings_sighandler);
+       signal(SIGHUP, thp_restore_settings_sighandler);
+       signal(SIGQUIT, thp_restore_settings_sighandler);
 }
 
 void thp_set_read_ahead_path(char *path)

diff --git a/tools/testing/selftests/mm/uffd-wp-mremap.c b/tools/testing/selftests/mm/uffd-wp-mremap.c
index 17186d4a4147127131dc537989976f06a06c622a..516c35d236e153ff8ea849b531f22d12b864ae4a 100644 (file)
--- a/tools/testing/selftests/mm/uffd-wp-mremap.c
+++ b/tools/testing/selftests/mm/uffd-wp-mremap.c
@@ -368,10 +368,6 @@ int main(int argc, char **argv)
                                       tc->swapout, tc->hugetlb);
        }
 
-       /* If THP is supported, restore original THP settings. */
-       if (nr_thpsizes)
-               thp_restore_settings();
-
        i = ksft_get_fail_cnt();
        if (i)
                ksft_exit_fail_msg("%d out of %d tests failed\n",