176 lines
4.6 KiB
C
176 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2012-2017 Red Hat, Inc.
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*/
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/*\
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* [Description]
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*
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* Detect heavy swapping during first time swap use.
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*
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* This case is used for testing kernel commit:
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* 50a15981a1fa ("[S390] reference bit testing for unmapped pages")
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*
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* The upstream commit fixed a issue on s390/x platform that heavy
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* swapping might occur in some condition, however since the patch
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* was quite general, this testcase will be run on all supported
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* platforms to ensure no regression been introduced.
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*
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* Details of the kernel fix:
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*
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* On x86 a page without a mapper is by definition not referenced / old.
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* The s390 architecture keeps the reference bit in the storage key and
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* the current code will check the storage key for page without a mapper.
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* This leads to an interesting effect: the first time an s390 system
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* needs to write pages to swap it only finds referenced pages. This
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* causes a lot of pages to get added and written to the swap device.
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* To avoid this behaviour change page_referenced to query the storage
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* key only if there is a mapper of the page.
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*
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* [Algorithm]
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*
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* Try to allocate memory which size is slightly larger than current
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* available memory. After allocation done, continue loop for a while
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* and calculate the used swap size. The used swap size should be small
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* enough, else it indicates that heavy swapping is occurred unexpectedly.
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*/
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "tst_safe_stdio.h"
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#include "lapi/abisize.h"
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#include "mem.h"
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/* allow swapping 1 * phy_mem in maximum */
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#define COE_DELTA 1
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/* will try to alloc 1.3 * phy_mem */
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#define COE_SLIGHT_OVER 0.3
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static void init_meminfo(void);
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static void do_alloc(int allow_raise);
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static void check_swapping(void);
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static long mem_available_init;
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static long swap_free_init;
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static long mem_over;
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static long mem_over_max;
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static pid_t pid;
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static unsigned int start_runtime;
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static void test_swapping(void)
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{
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#ifdef TST_ABI32
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tst_brk(TCONF, "test is not designed for 32-bit system.");
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#endif
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FILE *file;
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char line[PATH_MAX];
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start_runtime = tst_remaining_runtime();
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file = SAFE_FOPEN("/proc/swaps", "r");
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while (fgets(line, sizeof(line), file)) {
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if (strstr(line, "/dev/zram")) {
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SAFE_FCLOSE(file);
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tst_brk(TCONF, "zram-swap is being used!");
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}
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}
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SAFE_FCLOSE(file);
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init_meminfo();
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switch (pid = SAFE_FORK()) {
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case 0:
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do_alloc(0);
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do_alloc(1);
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exit(0);
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default:
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check_swapping();
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}
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}
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static void init_meminfo(void)
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{
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swap_free_init = SAFE_READ_MEMINFO("SwapFree:");
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mem_available_init = tst_available_mem();
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mem_over = mem_available_init * COE_SLIGHT_OVER;
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mem_over_max = mem_available_init * COE_DELTA;
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if (swap_free_init < mem_over_max)
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tst_brk(TCONF, "Not enough swap space to test: swap_free_init(%ldkB) < mem_over_max(%ldkB)",
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swap_free_init, mem_over_max);
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}
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static void do_alloc(int allow_raise)
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{
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long mem_count;
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void *s;
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if (allow_raise == 1)
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tst_res(TINFO, "available physical memory: %ld MB",
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mem_available_init / 1024);
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mem_count = mem_available_init + mem_over;
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if (allow_raise == 1)
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tst_res(TINFO, "try to allocate: %ld MB", mem_count / 1024);
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s = SAFE_MALLOC(mem_count * 1024);
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memset(s, 1, mem_count * 1024);
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if ((allow_raise == 1) && (raise(SIGSTOP) == -1)) {
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tst_res(TINFO, "memory allocated: %ld MB", mem_count / 1024);
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tst_brk(TBROK | TERRNO, "kill");
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}
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free(s);
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}
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static void check_swapping(void)
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{
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int status;
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long swap_free_now, swapped;
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/* wait child stop */
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SAFE_WAITPID(pid, &status, WUNTRACED);
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if (!WIFSTOPPED(status))
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tst_brk(TBROK, "child was not stopped.");
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/* Still occupying memory, loop for a while */
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while (tst_remaining_runtime() > start_runtime/2) {
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swap_free_now = SAFE_READ_MEMINFO("SwapFree:");
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sleep(1);
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long diff = labs(swap_free_now - SAFE_READ_MEMINFO("SwapFree:"));
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if (diff < 10)
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break;
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tst_res(TINFO, "SwapFree difference %li", diff);
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}
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swapped = SAFE_READ_PROC_STATUS(pid, "VmSwap:");
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if (swapped > mem_over_max) {
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kill(pid, SIGCONT);
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tst_brk(TFAIL, "heavy swapping detected: "
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"%ld MB swapped.", swapped / 1024);
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}
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tst_res(TPASS, "no heavy swapping detected, %ld MB swapped.",
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swapped / 1024);
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kill(pid, SIGCONT);
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/* wait child exit */
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SAFE_WAITPID(pid, &status, 0);
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}
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static struct tst_test test = {
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.needs_root = 1,
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.forks_child = 1,
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.min_mem_avail = 10,
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.max_runtime = 600,
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.test_all = test_swapping,
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.needs_kconfigs = (const char *[]) {
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"CONFIG_SWAP=y",
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NULL
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},
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.tags = (const struct tst_tag[]) {
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{"linux-git", "50a15981a1fa"},
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{}
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}
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};
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