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Message-ID: <CAKbZUD3KAqaYwc0b6OLzByma43FfZLqbn47fQwOwata_mGmeUw@mail.gmail.com>
Date: Sun, 19 Jan 2025 20:18:32 +0000
From: Pedro Falcato <pedro.falcato@...il.com>
To: Jiaqi Yan <jiaqiyan@...gle.com>
Cc: nao.horiguchi@...il.com, linmiaohe@...wei.com, sidhartha.kumar@...cle.com,
muchun.song@...ux.dev, jane.chu@...cle.com, akpm@...ux-foundation.org,
osalvador@...e.de, rientjes@...gle.com, jthoughton@...gle.com,
linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v1 1/2] selftest/mm: test HWPoison hugetlb truncation behavior
On Sun, Jan 19, 2025 at 6:06 PM Jiaqi Yan <jiaqiyan@...gle.com> wrote:
>
> Test based on my understanding of the memory failure recovery behavior
> for HugeTLB file system, especially after file is truncated/closed.
>
> Signed-off-by: Jiaqi Yan <jiaqiyan@...gle.com>
> ---
> tools/testing/selftests/mm/Makefile | 1 +
> tools/testing/selftests/mm/hugetlb-mfr-base.c | 240 ++++++++++++++++++
> 2 files changed, 241 insertions(+)
> create mode 100644 tools/testing/selftests/mm/hugetlb-mfr-base.c
>
> diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
> index 63ce39d024bb5..576626c93ccab 100644
> --- a/tools/testing/selftests/mm/Makefile
> +++ b/tools/testing/selftests/mm/Makefile
> @@ -62,6 +62,7 @@ TEST_GEN_FILES += hmm-tests
> TEST_GEN_FILES += hugetlb-madvise
> TEST_GEN_FILES += hugetlb-read-hwpoison
> TEST_GEN_FILES += hugetlb-soft-offline
> +TEST_GEN_FILES += hugetlb-mfr-base
> TEST_GEN_FILES += hugepage-mmap
> TEST_GEN_FILES += hugepage-mremap
> TEST_GEN_FILES += hugepage-shm
> diff --git a/tools/testing/selftests/mm/hugetlb-mfr-base.c b/tools/testing/selftests/mm/hugetlb-mfr-base.c
> new file mode 100644
> index 0000000000000..b8eee071babe6
> --- /dev/null
> +++ b/tools/testing/selftests/mm/hugetlb-mfr-base.c
> @@ -0,0 +1,240 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#define _GNU_SOURCE
> +#include <errno.h>
> +#include <pthread.h>
> +#include <signal.h>
> +#include <stdbool.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <unistd.h>
> +
> +#include <linux/magic.h>
> +#include <linux/memfd.h>
> +#include <sys/mman.h>
> +#include <sys/prctl.h>
> +#include <sys/statfs.h>
> +#include <sys/types.h>
> +
> +#include "../kselftest.h"
> +#include "vm_util.h"
> +
> +#define EPREFIX " !!! "
> +#define BYTE_LENTH_IN_1G 0x40000000
LENGTH, but the macro name itself is also a little weird-sounding
> +#define HUGETLB_FILL 0xab
> +
> +static void *sigbus_addr;
> +static int sigbus_addr_lsb;
> +static bool expecting_sigbus;
> +static bool got_sigbus;
> +static bool was_mceerr;
> +
> +static int create_hugetlbfs_file(struct statfs *file_stat)
> +{
> + int fd;
> + int flags = MFD_HUGETLB | MFD_HUGE_1GB;
> +
> + fd = memfd_create("hugetlb_tmp", flags);
> + if (fd < 0)
> + ksft_exit_fail_perror("Failed to memfd_create");
> +
> + memset(file_stat, 0, sizeof(*file_stat));
> + if (fstatfs(fd, file_stat)) {
> + close(fd);
> + ksft_exit_fail_perror("Failed to fstatfs");
> + }
> + if (file_stat->f_type != HUGETLBFS_MAGIC) {
> + close(fd);
> + ksft_exit_fail_msg("Not hugetlbfs file");
> + }
> +
> + ksft_print_msg("Created hugetlb_tmp file\n");
> + ksft_print_msg("hugepagesize=%#lx\n", file_stat->f_bsize);
> + if (file_stat->f_bsize != BYTE_LENTH_IN_1G)
> + ksft_exit_fail_msg("Hugepage size is not 1G");
> +
> + return fd;
> +}
> +
> +/*
> + * SIGBUS handler for "do_hwpoison" thread that mapped and MADV_HWPOISON
> + */
> +static void sigbus_handler(int signo, siginfo_t *info, void *context)
> +{
> + if (!expecting_sigbus)
> + ksft_exit_fail_msg("unexpected sigbus with addr=%p",
> + info->si_addr);
> +
> + got_sigbus = true;
> + was_mceerr = (info->si_code == BUS_MCEERR_AO ||
> + info->si_code == BUS_MCEERR_AR);
> + sigbus_addr = info->si_addr;
> + sigbus_addr_lsb = info->si_addr_lsb;
> +}
> +
> +static void *do_hwpoison(void *hwpoison_addr)
> +{
> + int hwpoison_size = getpagesize();
> +
> + ksft_print_msg("MADV_HWPOISON hwpoison_addr=%p, len=%d\n",
> + hwpoison_addr, hwpoison_size);
> + if (madvise(hwpoison_addr, hwpoison_size, MADV_HWPOISON) < 0)
> + ksft_exit_fail_perror("Failed to MADV_HWPOISON");
> +
> + pthread_exit(NULL);
> +}
> +
> +static void test_hwpoison_multiple_pages(unsigned char *start_addr)
> +{
> + pthread_t pthread;
> + int ret;
> + unsigned char *hwpoison_addr;
> + unsigned long offsets[] = {0x200000};
> +
> + for (size_t i = 0; i < ARRAY_SIZE(offsets); ++i) {
> + sigbus_addr = (void *)0xBADBADBAD;
> + sigbus_addr_lsb = 0;
> + was_mceerr = false;
> + got_sigbus = false;
> + expecting_sigbus = true;
> + hwpoison_addr = start_addr + offsets[i];
> +
> + ret = pthread_create(&pthread, NULL, &do_hwpoison, hwpoison_addr);
> + if (ret)
> + ksft_exit_fail_perror("Failed to create hwpoison thread");
> +
> + ksft_print_msg("Created thread to hwpoison and access hwpoison_addr=%p\n",
> + hwpoison_addr);
> +
> + pthread_join(pthread, NULL);
> +
> + if (!got_sigbus)
> + ksft_test_result_fail("Didn't get a SIGBUS\n");
> + if (!was_mceerr)
> + ksft_test_result_fail("Didn't get a BUS_MCEERR_A(R|O)\n");
> + if (sigbus_addr != hwpoison_addr)
> + ksft_test_result_fail("Incorrect address: got=%p, expected=%p\n",
> + sigbus_addr, hwpoison_addr);
> + if (sigbus_addr_lsb != 30)
> + ksft_test_result_fail("Incorrect address LSB: got=%d, expected=%d\n",
> + sigbus_addr_lsb, pshift());
> +
> + ksft_print_msg("Received expected and correct SIGBUS\n");
> + }
> +}
> +
> +static int read_nr_hugepages(unsigned long hugepage_size,
> + unsigned long *nr_hugepages)
> +{
> + char buffer[256] = {0};
> + char cmd[256] = {0};
> +
> + sprintf(cmd, "cat /sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages",
> + hugepage_size);
You'll notice this is just reading a file through an external command
> + FILE *cmdfile = popen(cmd, "r");
> +
> + if (cmdfile == NULL) {
> + ksft_perror(EPREFIX "failed to popen nr_hugepages");
> + return -1;
> + }
> +
> + if (!fgets(buffer, sizeof(buffer), cmdfile)) {
> + ksft_perror(EPREFIX "failed to read nr_hugepages");
> + pclose(cmdfile);
> + return -1;
> + }
and this is just reading a "file" (pipe) directly, soo....
static int read_nr_hugepages(...)
{
char path[256];
snprintf(path, 256,
/sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages",
hugepage_size);
FILE *file = fopen(path, "r");
fscanf(file, "%lu", nr_hugepages);
}
(error handling omitted)
--
Pedro
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