linux/tools/testing/selftests/vm/mlock2-tests.c
Michal Hocko eea274d64e selftests: vm: drop dependencies on page flags from mlock2 tests
It was noticed that mlock2 tests are failing after 9c4e6b1a70 ("mm,
mlock, vmscan: no more skipping pagevecs") because the patch has changed
the timing on when the page is added to the unevictable LRU list and thus
gains the unevictable page flag.

The test was just too dependent on the implementation details which were
true at the time when it was introduced.  Page flags and the timing when
they are set is something no userspace should ever depend on.  The test
should be testing only for the user observable contract of the tested
syscalls.  Those are defined pretty well for the mlock and there are other
means for testing them.  In fact this is already done and testing for page
flags can be safely dropped to achieve the aimed purpose.  Present bits
can be checked by /proc/<pid>/smaps RSS field and the locking state by
VmFlags although I would argue that Locked: field would be more
appropriate.

Drop all the page flag machinery and considerably simplify the test.  This
should be more robust for future kernel changes while checking the
promised contract is still valid.

Fixes: 9c4e6b1a70 ("mm, mlock, vmscan: no more skipping pagevecs")
Reported-by: Rafael Aquini <aquini@redhat.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Rafael Aquini <aquini@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Eric B Munson <emunson@akamai.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200324154218.GS19542@dhcp22.suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-04-02 09:35:31 -07:00

521 lines
10 KiB
C

// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <sys/mman.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <stdbool.h>
#include "mlock2.h"
#include "../kselftest.h"
struct vm_boundaries {
unsigned long start;
unsigned long end;
};
static int get_vm_area(unsigned long addr, struct vm_boundaries *area)
{
FILE *file;
int ret = 1;
char line[1024] = {0};
char *end_addr;
char *stop;
unsigned long start;
unsigned long end;
if (!area)
return ret;
file = fopen("/proc/self/maps", "r");
if (!file) {
perror("fopen");
return ret;
}
memset(area, 0, sizeof(struct vm_boundaries));
while(fgets(line, 1024, file)) {
end_addr = strchr(line, '-');
if (!end_addr) {
printf("cannot parse /proc/self/maps\n");
goto out;
}
*end_addr = '\0';
end_addr++;
stop = strchr(end_addr, ' ');
if (!stop) {
printf("cannot parse /proc/self/maps\n");
goto out;
}
stop = '\0';
sscanf(line, "%lx", &start);
sscanf(end_addr, "%lx", &end);
if (start <= addr && end > addr) {
area->start = start;
area->end = end;
ret = 0;
goto out;
}
}
out:
fclose(file);
return ret;
}
#define VMFLAGS "VmFlags:"
static bool is_vmflag_set(unsigned long addr, const char *vmflag)
{
char *line = NULL;
char *flags;
size_t size = 0;
bool ret = false;
FILE *smaps;
smaps = seek_to_smaps_entry(addr);
if (!smaps) {
printf("Unable to parse /proc/self/smaps\n");
goto out;
}
while (getline(&line, &size, smaps) > 0) {
if (!strstr(line, VMFLAGS)) {
free(line);
line = NULL;
size = 0;
continue;
}
flags = line + strlen(VMFLAGS);
ret = (strstr(flags, vmflag) != NULL);
goto out;
}
out:
free(line);
fclose(smaps);
return ret;
}
#define SIZE "Size:"
#define RSS "Rss:"
#define LOCKED "lo"
static unsigned long get_value_for_name(unsigned long addr, const char *name)
{
char *line = NULL;
size_t size = 0;
char *value_ptr;
FILE *smaps = NULL;
unsigned long value = -1UL;
smaps = seek_to_smaps_entry(addr);
if (!smaps) {
printf("Unable to parse /proc/self/smaps\n");
goto out;
}
while (getline(&line, &size, smaps) > 0) {
if (!strstr(line, name)) {
free(line);
line = NULL;
size = 0;
continue;
}
value_ptr = line + strlen(name);
if (sscanf(value_ptr, "%lu kB", &value) < 1) {
printf("Unable to parse smaps entry for Size\n");
goto out;
}
break;
}
out:
if (smaps)
fclose(smaps);
free(line);
return value;
}
static bool is_vma_lock_on_fault(unsigned long addr)
{
bool locked;
unsigned long vma_size, vma_rss;
locked = is_vmflag_set(addr, LOCKED);
if (!locked)
return false;
vma_size = get_value_for_name(addr, SIZE);
vma_rss = get_value_for_name(addr, RSS);
/* only one page is faulted in */
return (vma_rss < vma_size);
}
#define PRESENT_BIT 0x8000000000000000ULL
#define PFN_MASK 0x007FFFFFFFFFFFFFULL
#define UNEVICTABLE_BIT (1UL << 18)
static int lock_check(unsigned long addr)
{
bool locked;
unsigned long vma_size, vma_rss;
locked = is_vmflag_set(addr, LOCKED);
if (!locked)
return false;
vma_size = get_value_for_name(addr, SIZE);
vma_rss = get_value_for_name(addr, RSS);
return (vma_rss == vma_size);
}
static int unlock_lock_check(char *map)
{
if (is_vmflag_set((unsigned long)map, LOCKED)) {
printf("VMA flag %s is present on page 1 after unlock\n", LOCKED);
return 1;
}
return 0;
}
static int test_mlock_lock()
{
char *map;
int ret = 1;
unsigned long page_size = getpagesize();
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("test_mlock_locked mmap");
goto out;
}
if (mlock2_(map, 2 * page_size, 0)) {
if (errno == ENOSYS) {
printf("Cannot call new mlock family, skipping test\n");
_exit(KSFT_SKIP);
}
perror("mlock2(0)");
goto unmap;
}
if (!lock_check((unsigned long)map))
goto unmap;
/* Now unlock and recheck attributes */
if (munlock(map, 2 * page_size)) {
perror("munlock()");
goto unmap;
}
ret = unlock_lock_check(map);
unmap:
munmap(map, 2 * page_size);
out:
return ret;
}
static int onfault_check(char *map)
{
*map = 'a';
if (!is_vma_lock_on_fault((unsigned long)map)) {
printf("VMA is not marked for lock on fault\n");
return 1;
}
return 0;
}
static int unlock_onfault_check(char *map)
{
unsigned long page_size = getpagesize();
if (is_vma_lock_on_fault((unsigned long)map) ||
is_vma_lock_on_fault((unsigned long)map + page_size)) {
printf("VMA is still lock on fault after unlock\n");
return 1;
}
return 0;
}
static int test_mlock_onfault()
{
char *map;
int ret = 1;
unsigned long page_size = getpagesize();
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("test_mlock_locked mmap");
goto out;
}
if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
if (errno == ENOSYS) {
printf("Cannot call new mlock family, skipping test\n");
_exit(KSFT_SKIP);
}
perror("mlock2(MLOCK_ONFAULT)");
goto unmap;
}
if (onfault_check(map))
goto unmap;
/* Now unlock and recheck attributes */
if (munlock(map, 2 * page_size)) {
if (errno == ENOSYS) {
printf("Cannot call new mlock family, skipping test\n");
_exit(KSFT_SKIP);
}
perror("munlock()");
goto unmap;
}
ret = unlock_onfault_check(map);
unmap:
munmap(map, 2 * page_size);
out:
return ret;
}
static int test_lock_onfault_of_present()
{
char *map;
int ret = 1;
unsigned long page_size = getpagesize();
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("test_mlock_locked mmap");
goto out;
}
*map = 'a';
if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
if (errno == ENOSYS) {
printf("Cannot call new mlock family, skipping test\n");
_exit(KSFT_SKIP);
}
perror("mlock2(MLOCK_ONFAULT)");
goto unmap;
}
if (!is_vma_lock_on_fault((unsigned long)map) ||
!is_vma_lock_on_fault((unsigned long)map + page_size)) {
printf("VMA with present pages is not marked lock on fault\n");
goto unmap;
}
ret = 0;
unmap:
munmap(map, 2 * page_size);
out:
return ret;
}
static int test_munlockall()
{
char *map;
int ret = 1;
unsigned long page_size = getpagesize();
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("test_munlockall mmap");
goto out;
}
if (mlockall(MCL_CURRENT)) {
perror("mlockall(MCL_CURRENT)");
goto out;
}
if (!lock_check((unsigned long)map))
goto unmap;
if (munlockall()) {
perror("munlockall()");
goto unmap;
}
if (unlock_lock_check(map))
goto unmap;
munmap(map, 2 * page_size);
map = mmap(NULL, 2 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("test_munlockall second mmap");
goto out;
}
if (mlockall(MCL_CURRENT | MCL_ONFAULT)) {
perror("mlockall(MCL_CURRENT | MCL_ONFAULT)");
goto unmap;
}
if (onfault_check(map))
goto unmap;
if (munlockall()) {
perror("munlockall()");
goto unmap;
}
if (unlock_onfault_check(map))
goto unmap;
if (mlockall(MCL_CURRENT | MCL_FUTURE)) {
perror("mlockall(MCL_CURRENT | MCL_FUTURE)");
goto out;
}
if (!lock_check((unsigned long)map))
goto unmap;
if (munlockall()) {
perror("munlockall()");
goto unmap;
}
ret = unlock_lock_check(map);
unmap:
munmap(map, 2 * page_size);
out:
munlockall();
return ret;
}
static int test_vma_management(bool call_mlock)
{
int ret = 1;
void *map;
unsigned long page_size = getpagesize();
struct vm_boundaries page1;
struct vm_boundaries page2;
struct vm_boundaries page3;
map = mmap(NULL, 3 * page_size, PROT_READ | PROT_WRITE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (map == MAP_FAILED) {
perror("mmap()");
return ret;
}
if (call_mlock && mlock2_(map, 3 * page_size, MLOCK_ONFAULT)) {
if (errno == ENOSYS) {
printf("Cannot call new mlock family, skipping test\n");
_exit(KSFT_SKIP);
}
perror("mlock(ONFAULT)\n");
goto out;
}
if (get_vm_area((unsigned long)map, &page1) ||
get_vm_area((unsigned long)map + page_size, &page2) ||
get_vm_area((unsigned long)map + page_size * 2, &page3)) {
printf("couldn't find mapping in /proc/self/maps\n");
goto out;
}
/*
* Before we unlock a portion, we need to that all three pages are in
* the same VMA. If they are not we abort this test (Note that this is
* not a failure)
*/
if (page1.start != page2.start || page2.start != page3.start) {
printf("VMAs are not merged to start, aborting test\n");
ret = 0;
goto out;
}
if (munlock(map + page_size, page_size)) {
perror("munlock()");
goto out;
}
if (get_vm_area((unsigned long)map, &page1) ||
get_vm_area((unsigned long)map + page_size, &page2) ||
get_vm_area((unsigned long)map + page_size * 2, &page3)) {
printf("couldn't find mapping in /proc/self/maps\n");
goto out;
}
/* All three VMAs should be different */
if (page1.start == page2.start || page2.start == page3.start) {
printf("failed to split VMA for munlock\n");
goto out;
}
/* Now unlock the first and third page and check the VMAs again */
if (munlock(map, page_size * 3)) {
perror("munlock()");
goto out;
}
if (get_vm_area((unsigned long)map, &page1) ||
get_vm_area((unsigned long)map + page_size, &page2) ||
get_vm_area((unsigned long)map + page_size * 2, &page3)) {
printf("couldn't find mapping in /proc/self/maps\n");
goto out;
}
/* Now all three VMAs should be the same */
if (page1.start != page2.start || page2.start != page3.start) {
printf("failed to merge VMAs after munlock\n");
goto out;
}
ret = 0;
out:
munmap(map, 3 * page_size);
return ret;
}
static int test_mlockall(int (test_function)(bool call_mlock))
{
int ret = 1;
if (mlockall(MCL_CURRENT | MCL_ONFAULT | MCL_FUTURE)) {
perror("mlockall");
return ret;
}
ret = test_function(false);
munlockall();
return ret;
}
int main(int argc, char **argv)
{
int ret = 0;
ret += test_mlock_lock();
ret += test_mlock_onfault();
ret += test_munlockall();
ret += test_lock_onfault_of_present();
ret += test_vma_management(true);
ret += test_mlockall(test_vma_management);
return ret;
}