// SPDX-License-Identifier: GPL-2.0+
/*
* kselftest suite for mincore().
*
* Copyright (C) 2020 Collabora, Ltd.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <fcntl.h>
#include "../kselftest.h"
#include "../kselftest_harness.h"
/* Default test file size: 4MB */
#define MB (1UL << 20)
#define FILE_SIZE (4 * MB)
/*
* Tests the user interface. This test triggers most of the documented
* error conditions in mincore().
*/
TEST(basic_interface)
{
int retval;
int page_size;
unsigned char vec[1];
char *addr;
page_size = sysconf(_SC_PAGESIZE);
/* Query a 0 byte sized range */
retval = mincore(0, 0, vec);
EXPECT_EQ(0, retval);
/* Addresses in the specified range are invalid or unmapped */
errno = 0;
retval = mincore(NULL, page_size, vec);
EXPECT_EQ(-1, retval);
EXPECT_EQ(ENOMEM, errno);
errno = 0;
addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
ASSERT_NE(MAP_FAILED, addr) {
TH_LOG("mmap error: %s", strerror(errno));
}
/* <addr> argument is not page-aligned */
errno = 0;
retval = mincore(addr + 1, page_size, vec);
EXPECT_EQ(-1, retval);
EXPECT_EQ(EINVAL, errno);
/* <length> argument is too large */
errno = 0;
retval = mincore(addr, -1, vec);
EXPECT_EQ(-1, retval);
EXPECT_EQ(ENOMEM, errno);
/* <vec> argument points to an illegal address */
errno = 0;
retval = mincore(addr, page_size, NULL);
EXPECT_EQ(-1, retval);
EXPECT_EQ(EFAULT, errno);
munmap(addr, page_size);
}
/*
* Test mincore() behavior on a private anonymous page mapping.
* Check that the page is not loaded into memory right after the mapping
* but after accessing it (on-demand allocation).
* Then free the page and check that it's not memory-resident.
*/
TEST(check_anonymous_locked_pages)
{
unsigned char vec[1];
char *addr;
int retval;
int page_size;
page_size = sysconf(_SC_PAGESIZE);
/* Map one page and check it's not memory-resident */
errno = 0;
addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ASSERT_NE(MAP_FAILED, addr) {
TH_LOG("mmap error: %s", strerror(errno));
}
retval = mincore(addr, page_size, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(0, vec[0]) {
TH_LOG("Page found in memory before use");
}
/* Touch the page and check again. It should now be in memory */
addr[0] = 1;
mlock(addr, page_size);
retval = mincore(addr, page_size, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(1, vec[0]) {
TH_LOG("Page not found in memory after use");
}
/*
* It shouldn't be memory-resident after unlocking it and
* marking it as unneeded.
*/
munlock(addr, page_size);
madvise(addr, page_size, MADV_DONTNEED);
retval = mincore(addr, page_size, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(0, vec[0]) {
TH_LOG("Page in memory after being zapped");
}
munmap(addr, page_size);
}
/*
* Check mincore() behavior on huge pages.
* This test will be skipped if the mapping fails (ie. if there are no
* huge pages available).
*
* Make sure the system has at least one free huge page, check
* "HugePages_Free" in /proc/meminfo.
* Increment /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages if
* needed.
*/
TEST(check_huge_pages)
{
unsigned char vec[1];
char *addr;
int retval;
int page_size;
page_size = sysconf(_SC_PAGESIZE);
errno = 0;
addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB,
-1, 0);
if (addr == MAP_FAILED) {
if (errno == ENOMEM || errno == EINVAL)
SKIP(return, "No huge pages available or CONFIG_HUGETLB_PAGE disabled.");
else
TH_LOG("mmap error: %s", strerror(errno));
}
retval = mincore(addr, page_size, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(0, vec[0]) {
TH_LOG("Page found in memory before use");
}
addr[0] = 1;
mlock(addr, page_size);
retval = mincore(addr, page_size, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(1, vec[0]) {
TH_LOG("Page not found in memory after use");
}
munlock(addr, page_size);
munmap(addr, page_size);
}
/*
* Test mincore() behavior on a file-backed page.
* No pages should be loaded into memory right after the mapping. Then,
* accessing any address in the mapping range should load the page
* containing the address and a number of subsequent pages (readahead).
*
* The actual readahead settings depend on the test environment, so we
* can't make a lot of assumptions about that. This test covers the most
* general cases.
*/
TEST(check_file_mmap)
{
unsigned char *vec;
int vec_size;
char *addr;
int retval;
int page_size;
int fd;
int i;
int ra_pages = 0;
page_size = sysconf(_SC_PAGESIZE);
vec_size = FILE_SIZE / page_size;
if (FILE_SIZE % page_size)
vec_size++;
vec = calloc(vec_size, sizeof(unsigned char));
ASSERT_NE(NULL, vec) {
TH_LOG("Can't allocate array");
}
errno = 0;
fd = open(".", O_TMPFILE | O_RDWR, 0600);
if (fd < 0) {
ASSERT_EQ(errno, EOPNOTSUPP) {
TH_LOG("Can't create temporary file: %s",
strerror(errno));
}
SKIP(goto out_free, "O_TMPFILE not supported by filesystem.");
}
errno = 0;
retval = fallocate(fd, 0, 0, FILE_SIZE);
if (retval) {
ASSERT_EQ(errno, EOPNOTSUPP) {
TH_LOG("Error allocating space for the temporary file: %s",
strerror(errno));
}
SKIP(goto out_close, "fallocate not supported by filesystem.");
}
/*
* Map the whole file, the pages shouldn't be fetched yet.
*/
errno = 0;
addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
ASSERT_NE(MAP_FAILED, addr) {
TH_LOG("mmap error: %s", strerror(errno));
}
retval = mincore(addr, FILE_SIZE, vec);
ASSERT_EQ(0, retval);
for (i = 0; i < vec_size; i++) {
ASSERT_EQ(0, vec[i]) {
TH_LOG("Unexpected page in memory");
}
}
/*
* Touch a page in the middle of the mapping. We expect the next
* few pages (the readahead window) to be populated too.
*/
addr[FILE_SIZE / 2] = 1;
retval = mincore(addr, FILE_SIZE, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) {
TH_LOG("Page not found in memory after use");
}
i = FILE_SIZE / 2 / page_size + 1;
while (i < vec_size && vec[i]) {
ra_pages++;
i++;
}
EXPECT_GT(ra_pages, 0) {
TH_LOG("No read-ahead pages found in memory");
}
EXPECT_LT(i, vec_size) {
TH_LOG("Read-ahead pages reached the end of the file");
}
/*
* End of the readahead window. The rest of the pages shouldn't
* be in memory.
*/
if (i < vec_size) {
while (i < vec_size && !vec[i])
i++;
EXPECT_EQ(vec_size, i) {
TH_LOG("Unexpected page in memory beyond readahead window");
}
}
munmap(addr, FILE_SIZE);
out_close:
close(fd);
out_free:
free(vec);
}
/*
* Test mincore() behavior on a page backed by a tmpfs file. This test
* performs the same steps as the previous one. However, we don't expect
* any readahead in this case.
*/
TEST(check_tmpfs_mmap)
{
unsigned char *vec;
int vec_size;
char *addr;
int retval;
int page_size;
int fd;
int i;
int ra_pages = 0;
page_size = sysconf(_SC_PAGESIZE);
vec_size = FILE_SIZE / page_size;
if (FILE_SIZE % page_size)
vec_size++;
vec = calloc(vec_size, sizeof(unsigned char));
ASSERT_NE(NULL, vec) {
TH_LOG("Can't allocate array");
}
errno = 0;
fd = open("/dev/shm", O_TMPFILE | O_RDWR, 0600);
ASSERT_NE(-1, fd) {
TH_LOG("Can't create temporary file: %s",
strerror(errno));
}
errno = 0;
retval = fallocate(fd, 0, 0, FILE_SIZE);
ASSERT_EQ(0, retval) {
TH_LOG("Error allocating space for the temporary file: %s",
strerror(errno));
}
/*
* Map the whole file, the pages shouldn't be fetched yet.
*/
errno = 0;
addr = mmap(NULL, FILE_SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED, fd, 0);
ASSERT_NE(MAP_FAILED, addr) {
TH_LOG("mmap error: %s", strerror(errno));
}
retval = mincore(addr, FILE_SIZE, vec);
ASSERT_EQ(0, retval);
for (i = 0; i < vec_size; i++) {
ASSERT_EQ(0, vec[i]) {
TH_LOG("Unexpected page in memory");
}
}
/*
* Touch a page in the middle of the mapping. We expect only
* that page to be fetched into memory.
*/
addr[FILE_SIZE / 2] = 1;
retval = mincore(addr, FILE_SIZE, vec);
ASSERT_EQ(0, retval);
ASSERT_EQ(1, vec[FILE_SIZE / 2 / page_size]) {
TH_LOG("Page not found in memory after use");
}
i = FILE_SIZE / 2 / page_size + 1;
while (i < vec_size && vec[i]) {
ra_pages++;
i++;
}
ASSERT_EQ(ra_pages, 0) {
TH_LOG("Read-ahead pages found in memory");
}
munmap(addr, FILE_SIZE);
close(fd);
free(vec);
}
TEST_HARNESS_MAIN
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