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selftests: cachestat: add tests for mmap, refactor and enhance mmap test for cachestat validation

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Add a cohesive test case that verifies cachestat behavior with
memory-mapped files using mmap().  Also refactor the test logic to reduce
redundancy, improve error reporting, and clarify failure messages for both
shmem and mmap file types.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20250709174657.6916-1-suresh.k.chandrappa@gmail.com
Signed-off-by: Suresh K C <suresh.k.chandrappa@gmail.com>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Tested-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Suresh K C 2025-07-09 23:16:57 +05:30 committed by Andrew Morton
parent 881388f343
commit d6a511dea4
1 changed files with 54 additions and 8 deletions
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62
tools/testing/selftests/cachestat/test_cachestat.c
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@ -33,6 +33,11 @@ void print_cachestat(struct cachestat *cs)
cs->nr_evicted, cs->nr_recently_evicted);
}
enum file_type {
FILE_MMAP,
FILE_SHMEM
};
bool write_exactly(int fd, size_t filesize)
{
int random_fd = open("/dev/urandom", O_RDONLY);
@ -201,8 +206,20 @@ static int test_cachestat(const char *filename, bool write_random, bool create,
out:
return ret;
}
const char *file_type_str(enum file_type type)
{
switch (type) {
case FILE_SHMEM:
return "shmem";
case FILE_MMAP:
return "mmap";
default:
return "unknown";
}
}
bool test_cachestat_shmem(void)
bool run_cachestat_test(enum file_type type)
{
size_t PS = sysconf(_SC_PAGESIZE);
size_t filesize = PS * 512 * 2; /* 2 2MB huge pages */
@ -212,27 +229,50 @@ bool test_cachestat_shmem(void)
char *filename = "tmpshmcstat";
struct cachestat cs;
bool ret = true;
int fd;
unsigned long num_pages = compute_len / PS;
int fd = shm_open(filename, O_CREAT | O_RDWR, 0600);
if (type == FILE_SHMEM)
fd = shm_open(filename, O_CREAT | O_RDWR, 0600);
else
fd = open(filename, O_RDWR | O_CREAT | O_TRUNC, 0666);
if (fd < 0) {
ksft_print_msg("Unable to create shmem file.\n");
ksft_print_msg("Unable to create %s file.\n",
file_type_str(type));
ret = false;
goto out;
}
if (ftruncate(fd, filesize)) {
ksft_print_msg("Unable to truncate shmem file.\n");
ksft_print_msg("Unable to truncate %s file.\n",file_type_str(type));
ret = false;
goto close_fd;
}
switch (type) {
case FILE_SHMEM:
if (!write_exactly(fd, filesize)) {
ksft_print_msg("Unable to write to file.\n");
ret = false;
goto close_fd;
}
break;
case FILE_MMAP:
char *map = mmap(NULL, filesize, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
if (!write_exactly(fd, filesize)) {
ksft_print_msg("Unable to write to shmem file.\n");
if (map == MAP_FAILED) {
ksft_print_msg("mmap failed.\n");
ret = false;
goto close_fd;
}
for (int i = 0; i < filesize; i++)
map[i] = 'A';
break;
default:
ksft_print_msg("Unsupported file type.\n");
ret = false;
goto close_fd;
}
syscall_ret = syscall(__NR_cachestat, fd, &cs_range, &cs, 0);
if (syscall_ret) {
@ -308,12 +348,18 @@ int main(void)
break;
}
if (test_cachestat_shmem())
if (run_cachestat_test(FILE_SHMEM))
ksft_test_result_pass("cachestat works with a shmem file\n");
else {
ksft_test_result_fail("cachestat fails with a shmem file\n");
ret = 1;
}
if (run_cachestat_test(FILE_MMAP))
ksft_test_result_pass("cachestat works with a mmap file\n");
else {
ksft_test_result_fail("cachestat fails with a mmap file\n");
ret = 1;
}
return ret;
}