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selftests: vm: add KSM zero page merging test

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Add check_ksm_zero_page_merge() function to test that empty pages are
being handled properly.  For this, several zero pages are allocated and
merged using madvise.  If use_zero_pages is enabled, the pages must be
shared with the special kernel zero pages; otherwise, they are merged as
usual duplicate pages.  The test is run as follows: ./ksm_tests -Z

Link: https://lkml.kernel.org/r/6d0caab00d4bdccf5e3791cb95cf6dfd5eb85e45.1626252248.git.zhansayabagdaulet@gmail.com
Signed-off-by: Zhansaya Bagdauletkyzy <zhansayabagdaulet@gmail.com>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Zhansaya Bagdauletkyzy 2021-09-02 15:00:45 -07:00 committed by Linus Torvalds
parent a40c80e348
commit 39619982c5
2 changed files with 99 additions and 3 deletions
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70
tools/testing/selftests/vm/ksm_tests.c
View file

@ -12,6 +12,7 @@
#define KSM_SCAN_LIMIT_SEC_DEFAULT 120
#define KSM_PAGE_COUNT_DEFAULT 10l
#define KSM_PROT_STR_DEFAULT "rw"
#define KSM_USE_ZERO_PAGES_DEFAULT false
struct ksm_sysfs {
unsigned long max_page_sharing;
@ -25,7 +26,8 @@ struct ksm_sysfs {
enum ksm_test_name {
CHECK_KSM_MERGE,
CHECK_KSM_UNMERGE
CHECK_KSM_UNMERGE,
CHECK_KSM_ZERO_PAGE_MERGE
};
static int ksm_write_sysfs(const char *file_path, unsigned long val)
@ -80,10 +82,12 @@ static int str_to_prot(char *prot_str)
static void print_help(void)
{
printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n");
printf("usage: ksm_tests [-h] <test type> [-a prot] [-p page_count] [-l timeout]\n"
"[-z use_zero_pages]\n");
printf("Supported <test type>:\n"
" -M (page merging)\n"
" -Z (zero pages merging)\n"
" -U (page unmerging)\n\n");
printf(" -a: specify the access protections of pages.\n"
@ -93,6 +97,8 @@ static void print_help(void)
" Default: %ld\n", KSM_PAGE_COUNT_DEFAULT);
printf(" -l: limit the maximum running time (in seconds) for a test.\n"
" Default: %d seconds\n", KSM_SCAN_LIMIT_SEC_DEFAULT);
printf(" -z: change use_zero_pages tunable\n"
" Default: %d\n", KSM_USE_ZERO_PAGES_DEFAULT);
exit(0);
}
@ -289,6 +295,50 @@ static int check_ksm_unmerge(int mapping, int prot, int timeout, size_t page_siz
return KSFT_FAIL;
}
static int check_ksm_zero_page_merge(int mapping, int prot, long page_count, int timeout,
bool use_zero_pages, size_t page_size)
{
void *map_ptr;
struct timespec start_time;
if (clock_gettime(CLOCK_MONOTONIC_RAW, &start_time)) {
perror("clock_gettime");
return KSFT_FAIL;
}
if (ksm_write_sysfs(KSM_FP("use_zero_pages"), use_zero_pages))
return KSFT_FAIL;
/* fill pages with zero and try to merge them */
map_ptr = allocate_memory(NULL, prot, mapping, 0, page_size * page_count);
if (!map_ptr)
return KSFT_FAIL;
if (ksm_merge_pages(map_ptr, page_size * page_count, start_time, timeout))
goto err_out;
/*
* verify that the right number of pages are merged:
* 1) if use_zero_pages is set to 1, empty pages are merged
* with the kernel zero page instead of with each other;
* 2) if use_zero_pages is set to 0, empty pages are not treated specially
* and merged as usual.
*/
if (use_zero_pages && !assert_ksm_pages_count(0))
goto err_out;
else if (!use_zero_pages && !assert_ksm_pages_count(page_count))
goto err_out;
printf("OK\n");
munmap(map_ptr, page_size * page_count);
return KSFT_PASS;
err_out:
printf("Not OK\n");
munmap(map_ptr, page_size * page_count);
return KSFT_FAIL;
}
int main(int argc, char *argv[])
{
int ret, opt;
@ -298,8 +348,9 @@ int main(int argc, char *argv[])
size_t page_size = sysconf(_SC_PAGESIZE);
struct ksm_sysfs ksm_sysfs_old;
int test_name = CHECK_KSM_MERGE;
bool use_zero_pages = KSM_USE_ZERO_PAGES_DEFAULT;
while ((opt = getopt(argc, argv, "ha:p:l:MU")) != -1) {
while ((opt = getopt(argc, argv, "ha:p:l:z:MUZ")) != -1) {
switch (opt) {
case 'a':
prot = str_to_prot(optarg);
@ -321,11 +372,20 @@ int main(int argc, char *argv[])
case 'h':
print_help();
break;
case 'z':
if (strcmp(optarg, "0") == 0)
use_zero_pages = 0;
else
use_zero_pages = 1;
break;
case 'M':
break;
case 'U':
test_name = CHECK_KSM_UNMERGE;
break;
case 'Z':
test_name = CHECK_KSM_ZERO_PAGE_MERGE;
break;
default:
return KSFT_FAIL;
}
@ -359,6 +419,10 @@ int main(int argc, char *argv[])
ret = check_ksm_unmerge(MAP_PRIVATE | MAP_ANONYMOUS, prot, ksm_scan_limit_sec,
page_size);
break;
case CHECK_KSM_ZERO_PAGE_MERGE:
ret = check_ksm_zero_page_merge(MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count,
ksm_scan_limit_sec, use_zero_pages, page_size);
break;
}
if (ksm_restore(&ksm_sysfs_old)) {

32
tools/testing/selftests/vm/run_vmtests.sh
View file

@ -409,6 +409,38 @@ else
exitcode=1
fi
echo "----------------------------------------------------------"
echo "running KSM test with 10 zero pages and use_zero_pages = 0"
echo "----------------------------------------------------------"
./ksm_tests -Z -p 10 -z 0
ret_val=$?
if [ $ret_val -eq 0 ]; then
echo "[PASS]"
elif [ $ret_val -eq $ksft_skip ]; then
echo "[SKIP]"
exitcode=$ksft_skip
else
echo "[FAIL]"
exitcode=1
fi
echo "----------------------------------------------------------"
echo "running KSM test with 10 zero pages and use_zero_pages = 1"
echo "----------------------------------------------------------"
./ksm_tests -Z -p 10 -z 1
ret_val=$?
if [ $ret_val -eq 0 ]; then
echo "[PASS]"
elif [ $ret_val -eq $ksft_skip ]; then
echo "[SKIP]"
exitcode=$ksft_skip
else
echo "[FAIL]"
exitcode=1
fi
exit $exitcode
exit $exitcode