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selftests/mm: verify droppable mappings cannot be locked

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For configs that support MAP_DROPPABLE verify that a mapping created with
MAP_DROPPABLE cannot be locked via mlock(), and that it will not be locked
if it's created after mlockall(MCL_FUTURE).

Link: https://lore.kernel.org/20260416033939.49981-3-anthony.yznaga@oracle.com
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Liam Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Anthony Yznaga 2026-04-15 20:39:38 -07:00 committed by Andrew Morton
parent d86c9e971a
commit c02dd57c57
1 changed files with 76 additions and 10 deletions
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86
tools/testing/selftests/mm/mlock2-tests.c
View File

@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <sys/mman.h>
#include <linux/mman.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
@ -163,14 +164,17 @@ static int lock_check(unsigned long addr)
return (vma_rss == vma_size);
}
static int unlock_lock_check(char *map)
static int unlock_lock_check(char *map, bool mlock_supported)
{
if (is_vmflag_set((unsigned long)map, LOCKED)) {
ksft_print_msg("VMA flag %s is present on page 1 after unlock\n", LOCKED);
return 1;
}
if (!is_vmflag_set((unsigned long)map, LOCKED))
return 0;
return 0;
if (mlock_supported)
ksft_print_msg("VMA flag %s is present on page 1 after unlock\n", LOCKED);
else
ksft_print_msg("VMA flag %s is present on an unsupported VMA\n", LOCKED);
return 1;
}
static void test_mlock_lock(void)
@ -196,7 +200,7 @@ static void test_mlock_lock(void)
ksft_exit_fail_msg("munlock(): %s\n", strerror(errno));
}
ksft_test_result(!unlock_lock_check(map), "%s: Unlocked\n", __func__);
ksft_test_result(!unlock_lock_check(map, true), "%s: Unlocked\n", __func__);
munmap(map, 2 * page_size);
}
@ -296,7 +300,7 @@ static void test_munlockall0(void)
ksft_exit_fail_msg("munlockall(): %s\n", strerror(errno));
}
ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
munmap(map, 2 * page_size);
}
@ -336,7 +340,67 @@ static void test_munlockall1(void)
ksft_exit_fail_msg("munlockall() %s\n", strerror(errno));
}
ksft_test_result(!unlock_lock_check(map), "%s: No locked memory\n", __func__);
ksft_test_result(!unlock_lock_check(map, true), "%s: No locked memory\n", __func__);
munmap(map, 2 * page_size);
}
/* Droppable memory should not be lockable. */
static void test_mlock_droppable(void)
{
char *map;
unsigned long page_size = getpagesize();
/* Ensure MCL_FUTURE is not set. */
if (munlockall()) {
ksft_test_result_fail("munlockall() %s\n", strerror(errno));
return;
}
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
if (map == MAP_FAILED) {
if ((errno == EOPNOTSUPP) || (errno == EINVAL))
ksft_test_result_skip("%s: MAP_DROPPABLE not supported\n", __func__);
else
ksft_test_result_fail("mmap error: %s\n", strerror(errno));
return;
}
if (mlock2_(map, 2 * page_size, 0))
ksft_test_result_fail("mlock2(0): %s\n", strerror(errno));
else
ksft_test_result(!unlock_lock_check(map, false),
"%s: droppable memory not locked\n", __func__);
munmap(map, 2 * page_size);
}
static void test_mlockall_future_droppable(void)
{
char *map;
unsigned long page_size = getpagesize();
if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
ksft_test_result_fail("mlockall(MCL_CURRENT | MCL_FUTURE): %s\n", strerror(errno));
return;
}
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_DROPPABLE, -1, 0);
if (map == MAP_FAILED) {
if ((errno == EOPNOTSUPP) || (errno == EINVAL))
ksft_test_result_skip("%s: MAP_DROPPABLE not supported\n", __func__);
else
ksft_test_result_fail("mmap error: %s\n", strerror(errno));
munlockall();
return;
}
ksft_test_result(!unlock_lock_check(map, false), "%s: droppable memory not locked\n",
__func__);
munlockall();
munmap(map, 2 * page_size);
}
@ -442,7 +506,7 @@ int main(int argc, char **argv)
munmap(map, size);
ksft_set_plan(13);
ksft_set_plan(15);
test_mlock_lock();
test_mlock_onfault();
@ -451,6 +515,8 @@ int main(int argc, char **argv)
test_lock_onfault_of_present();
test_vma_management(true);
test_mlockall();
test_mlock_droppable();
test_mlockall_future_droppable();
ksft_finished();
}