On Mon, Mar 21, 2022 at 10:21:28AM -0400, Zi Yan wrote:
> From: Zi Yan <ziy@xxxxxxxxxx>
>
> It is used to test split_huge_page_to_list_to_order for pagecache THPs.
> Also add test cases for split_huge_page_to_list_to_order via both
> debugfs, truncating a file, and punching holes in a file.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Thanks!
> ---
> mm/huge_memory.c | 26 ++-
> .../selftests/vm/split_huge_page_test.c | 219 +++++++++++++++---
> 2 files changed, 201 insertions(+), 44 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 76db0092a1e2..7645bb12fcbc 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2856,7 +2856,7 @@ static inline bool vma_not_suitable_for_thp_split(struct vm_area_struct *vma)
> }
>
> static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
> - unsigned long vaddr_end)
> + unsigned long vaddr_end, unsigned int new_order)
> {
> int ret = 0;
> struct task_struct *task;
> @@ -2926,7 +2926,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
> if (!trylock_page(page))
> goto next;
>
> - if (!split_huge_page(page))
> + if (!split_huge_page_to_list_to_order(page, NULL, new_order))
> split++;
>
> unlock_page(page);
> @@ -2944,7 +2944,7 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start,
> }
>
> static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
> - pgoff_t off_end)
> + pgoff_t off_end, unsigned int new_order)
> {
> struct filename *file;
> struct file *candidate;
> @@ -2984,7 +2984,7 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start,
> if (!trylock_page(fpage))
> goto next;
>
> - if (!split_huge_page(fpage))
> + if (!split_huge_page_to_list_to_order(fpage, NULL, new_order))
> split++;
>
> unlock_page(fpage);
> @@ -3009,10 +3009,14 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
> {
> static DEFINE_MUTEX(split_debug_mutex);
> ssize_t ret;
> - /* hold pid, start_vaddr, end_vaddr or file_path, off_start, off_end */
> + /*
> + * hold pid, start_vaddr, end_vaddr, new_order or
> + * file_path, off_start, off_end, new_order
> + */
> char input_buf[MAX_INPUT_BUF_SZ];
> int pid;
> unsigned long vaddr_start, vaddr_end;
> + unsigned int new_order = 0;
>
> ret = mutex_lock_interruptible(&split_debug_mutex);
> if (ret)
> @@ -3041,29 +3045,29 @@ static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
> goto out;
> }
>
> - ret = sscanf(buf, "0x%lx,0x%lx", &off_start, &off_end);
> - if (ret != 2) {
> + ret = sscanf(buf, "0x%lx,0x%lx,%d", &off_start, &off_end, &new_order);
> + if (ret != 2 && ret != 3) {
> ret = -EINVAL;
> goto out;
> }
> - ret = split_huge_pages_in_file(file_path, off_start, off_end);
> + ret = split_huge_pages_in_file(file_path, off_start, off_end, new_order);
> if (!ret)
> ret = input_len;
>
> goto out;
> }
>
> - ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
> + ret = sscanf(input_buf, "%d,0x%lx,0x%lx,%d", &pid, &vaddr_start, &vaddr_end, &new_order);
> if (ret == 1 && pid == 1) {
> split_huge_pages_all();
> ret = strlen(input_buf);
> goto out;
> - } else if (ret != 3) {
> + } else if (ret != 3 && ret != 4) {
> ret = -EINVAL;
> goto out;
> }
>
> - ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end);
> + ret = split_huge_pages_pid(pid, vaddr_start, vaddr_end, new_order);
> if (!ret)
> ret = strlen(input_buf);
> out:
> diff --git a/tools/testing/selftests/vm/split_huge_page_test.c b/tools/testing/selftests/vm/split_huge_page_test.c
> index 52497b7b9f1d..af01e7dca9c8 100644
> --- a/tools/testing/selftests/vm/split_huge_page_test.c
> +++ b/tools/testing/selftests/vm/split_huge_page_test.c
> @@ -16,6 +16,7 @@
> #include <sys/mount.h>
> #include <malloc.h>
> #include <stdbool.h>
> +#include <time.h>
>
> uint64_t pagesize;
> unsigned int pageshift;
> @@ -24,10 +25,11 @@ uint64_t pmd_pagesize;
> #define PMD_SIZE_PATH "/sys/kernel/mm/transparent_hugepage/hpage_pmd_size"
> #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
> #define SMAP_PATH "/proc/self/smaps"
> +#define THP_FS_PATH "/mnt/thp_fs"
> #define INPUT_MAX 80
>
> -#define PID_FMT "%d,0x%lx,0x%lx"
> -#define PATH_FMT "%s,0x%lx,0x%lx"
> +#define PID_FMT "%d,0x%lx,0x%lx,%d"
> +#define PATH_FMT "%s,0x%lx,0x%lx,%d"
>
> #define PFN_MASK ((1UL<<55)-1)
> #define KPF_THP (1UL<<22)
> @@ -75,23 +77,6 @@ static uint64_t read_pmd_pagesize(void)
> return strtoul(buf, NULL, 10);
> }
>
> -static int write_file(const char *path, const char *buf, size_t buflen)
> -{
> - int fd;
> - ssize_t numwritten;
> -
> - fd = open(path, O_WRONLY);
> - if (fd == -1)
> - return 0;
> -
> - numwritten = write(fd, buf, buflen - 1);
> - close(fd);
> - if (numwritten < 1)
> - return 0;
> -
> - return (unsigned int) numwritten;
> -}
> -
> static void write_debugfs(const char *fmt, ...)
> {
> char input[INPUT_MAX];
> @@ -106,11 +91,6 @@ static void write_debugfs(const char *fmt, ...)
> printf("%s: Debugfs input is too long\n", __func__);
> exit(EXIT_FAILURE);
> }
> -
> - if (!write_file(SPLIT_DEBUGFS, input, ret + 1)) {
> - perror(SPLIT_DEBUGFS);
> - exit(EXIT_FAILURE);
> - }
> }
>
> #define MAX_LINE_LENGTH 500
> @@ -124,7 +104,7 @@ static bool check_for_pattern(FILE *fp, const char *pattern, char *buf)
> return false;
> }
>
> -static uint64_t check_huge(void *addr)
> +static uint64_t check_huge(void *addr, const char *prefix)
> {
> uint64_t thp = 0;
> int ret;
> @@ -149,13 +129,13 @@ static uint64_t check_huge(void *addr)
> goto err_out;
>
> /*
> - * Fetch the AnonHugePages: in the same block and check the number of
> + * Fetch the @prefix in the same block and check the number of
> * hugepages.
> */
> - if (!check_for_pattern(fp, "AnonHugePages:", buffer))
> + if (!check_for_pattern(fp, prefix, buffer))
> goto err_out;
>
> - if (sscanf(buffer, "AnonHugePages:%10ld kB", &thp) != 1) {
> + if (sscanf(&buffer[strlen(prefix)], "%10ld kB", &thp) != 1) {
> printf("Reading smap error\n");
> exit(EXIT_FAILURE);
> }
> @@ -184,7 +164,7 @@ void split_pmd_thp(void)
> for (i = 0; i < len; i++)
> one_page[i] = (char)i;
>
> - thp_size = check_huge(one_page);
> + thp_size = check_huge(one_page, "AnonHugePages:");
> if (!thp_size) {
> printf("No THP is allocated\n");
> exit(EXIT_FAILURE);
> @@ -192,7 +172,7 @@ void split_pmd_thp(void)
>
> /* split all THPs */
> write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
> - (uint64_t)one_page + len);
> + (uint64_t)one_page + len, 0);
>
> for (i = 0; i < len; i++)
> if (one_page[i] != (char)i) {
> @@ -201,7 +181,7 @@ void split_pmd_thp(void)
> }
>
>
> - thp_size = check_huge(one_page);
> + thp_size = check_huge(one_page, "AnonHugePages:");
> if (thp_size) {
> printf("Still %ld kB AnonHugePages not split\n", thp_size);
> exit(EXIT_FAILURE);
> @@ -249,7 +229,7 @@ void split_pte_mapped_thp(void)
> for (i = 0; i < len; i++)
> one_page[i] = (char)i;
>
> - thp_size = check_huge(one_page);
> + thp_size = check_huge(one_page, "AnonHugePages:");
> if (!thp_size) {
> printf("No THP is allocated\n");
> exit(EXIT_FAILURE);
> @@ -284,7 +264,7 @@ void split_pte_mapped_thp(void)
>
> /* split all remapped THPs */
> write_debugfs(PID_FMT, getpid(), (uint64_t)pte_mapped,
> - (uint64_t)pte_mapped + pagesize * 4);
> + (uint64_t)pte_mapped + pagesize * 4, 0);
>
> /* smap does not show THPs after mremap, use kpageflags instead */
> thp_size = 0;
> @@ -371,20 +351,193 @@ void split_file_backed_thp(void)
> printf("file-backed THP split test done, please check dmesg for more information\n");
> }
>
> +void create_pagecache_thp_and_fd(const char *testfile, size_t fd_size, int *fd, char **addr)
> +{
> + size_t i;
> + int dummy;
> +
> + srand(time(NULL));
> +
> + *fd = open(testfile, O_CREAT | O_RDWR, 0664);
> + if (*fd == -1) {
> + perror("Failed to create a file at "THP_FS_PATH);
> + exit(EXIT_FAILURE);
> + }
> +
> + for (i = 0; i < fd_size; i++) {
> + unsigned char byte = (unsigned char)i;
> +
> + write(*fd, &byte, sizeof(byte));
> + }
> + close(*fd);
> + sync();
> + *fd = open("/proc/sys/vm/drop_caches", O_WRONLY);
> + if (*fd == -1) {
> + perror("open drop_caches");
> + exit(EXIT_FAILURE);
> + }
> + if (write(*fd, "3", 1) != 1) {
> + perror("write to drop_caches");
> + exit(EXIT_FAILURE);
> + }
> + close(*fd);
> +
> + *fd = open(testfile, O_RDWR);
> + if (*fd == -1) {
> + perror("Failed to open a file at "THP_FS_PATH);
> + exit(EXIT_FAILURE);
> + }
> +
> + *addr = mmap(NULL, fd_size, PROT_READ|PROT_WRITE, MAP_SHARED, *fd, 0);
> + if (*addr == (char *)-1) {
> + perror("cannot mmap");
> + exit(1);
> + }
> + madvise(*addr, fd_size, MADV_HUGEPAGE);
> +
> + for (size_t i = 0; i < fd_size; i++)
> + dummy += *(*addr + i);
> +
> + if (!check_huge(*addr, "FilePmdMapped:")) {
> + printf("No pagecache THP generated, please mount a filesystem "
> + "supporting pagecache THP at "THP_FS_PATH"\n");
> + exit(EXIT_FAILURE);
> + }
> +}
> +
> +void split_thp_in_pagecache_to_order(size_t fd_size, int order)
> +{
> + int fd;
> + char *addr;
> + size_t i;
> + const char testfile[] = THP_FS_PATH "/test";
> +
> + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr);
> +
> + printf("split %ld kB pagecache page to order %d ... ", fd_size >> 10, order);
> + write_debugfs(PID_FMT, getpid(), (uint64_t)addr, (uint64_t)addr + fd_size, order);
> +
> + for (i = 0; i < fd_size; i++)
> + if (*(addr + i) != (char)i) {
> + printf("%lu byte corrupted in the file\n", i);
> + exit(EXIT_FAILURE);
> + }
> +
> + close(fd);
> + unlink(testfile);
> + printf("done\n");
> +}
> +
> +void truncate_thp_in_pagecache_to_order(size_t fd_size, int order)
> +{
> + int fd;
> + char *addr;
> + size_t i;
> + const char testfile[] = THP_FS_PATH "/test";
> +
> + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr);
> +
> + printf("truncate %ld kB pagecache page to size %lu kB ... ", fd_size >> 10, 4UL << order);
> + ftruncate(fd, pagesize << order);
> +
> + for (i = 0; i < (pagesize << order); i++)
> + if (*(addr + i) != (char)i) {
> + printf("%lu byte corrupted in the file\n", i);
> + exit(EXIT_FAILURE);
> + }
> +
> + close(fd);
> + unlink(testfile);
> + printf("done\n");
> +}
> +
> +void punch_hole_in_pagecache_thp(size_t fd_size, off_t offset[], off_t len[], int n)
> +{
> + int fd, j;
> + char *addr;
> + size_t i;
> + const char testfile[] = THP_FS_PATH "/test";
> +
> + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr);
> +
> + for (j = 0; j < n; j++) {
> + printf("addr: %lx, punch a hole at offset %ld kB with len %ld kB ... ",
> + (unsigned long)addr, offset[j] >> 10, len[j] >> 10);
> + fallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, offset[j], len[j]);
> + printf("done\n");
> + }
> +
> + for (i = 0; i < fd_size; i++) {
> + int in_hole = 0;
> +
> + for (j = 0; j < n; j++)
> + if (i >= offset[j] && i <= (offset[j] + len[j])) {
> + in_hole = 1;
> + break;
> + }
> +
> + if (in_hole) {
> + if (*(addr + i)) {
> + printf("%lu byte non-zero after punch\n", i);
> + exit(EXIT_FAILURE);
> + }
> + continue;
> + }
> + if (*(addr + i) != (char)i) {
> + printf("%lu byte corrupted in the file\n", i);
> + exit(EXIT_FAILURE);
> + }
> + }
> +
> + close(fd);
> + unlink(testfile);
> +}
> +
> int main(int argc, char **argv)
> {
> + int i;
> + size_t fd_size;
> + off_t offset[2], len[2];
> +
> if (geteuid() != 0) {
> printf("Please run the benchmark as root\n");
> exit(EXIT_FAILURE);
> }
>
> + setbuf(stdout, NULL);
> +
> pagesize = getpagesize();
> pageshift = ffs(pagesize) - 1;
> pmd_pagesize = read_pmd_pagesize();
> + fd_size = 2 * pmd_pagesize;
>
> split_pmd_thp();
> split_pte_mapped_thp();
> split_file_backed_thp();
>
> + for (i = 8; i >= 0; i--)
> + if (i != 1)
> + split_thp_in_pagecache_to_order(fd_size, i);
> +
> + /*
> + * for i is 1, truncate code in the kernel should create order-0 pages
> + * instead of order-1 THPs, since order-1 THP is not supported. No error
> + * is expected.
> + */
> + for (i = 8; i >= 0; i--)
> + truncate_thp_in_pagecache_to_order(fd_size, i);
> +
> + offset[0] = 123 * pagesize;
> + offset[1] = 4 * pagesize;
> + len[0] = 200 * pagesize;
> + len[1] = 16 * pagesize;
> + punch_hole_in_pagecache_thp(fd_size, offset, len, 2);
> +
> + offset[0] = 259 * pagesize + pagesize / 2;
> + offset[1] = 33 * pagesize;
> + len[0] = 129 * pagesize;
> + len[1] = 16 * pagesize;
> + punch_hole_in_pagecache_thp(fd_size, offset, len, 2);
> +
> return 0;
> }
> --
> 2.35.1
>
