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