From: Zi Yan ziy@nvidia.com
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@nvidia.com --- mm/huge_memory.c | 34 ++- .../selftests/mm/split_huge_page_test.c | 225 +++++++++++++++++- 2 files changed, 242 insertions(+), 17 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f119b9be33f2..cadb13e3224f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3024,7 +3024,7 @@ 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; @@ -3086,13 +3086,19 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, goto next;
total++; - if (!can_split_folio(page_folio(page), NULL)) + /* + * For folios with private, split_huge_page_to_list_to_order() + * will try to drop it before split and then check if the folio + * can be split or not. So skip the check here. + */ + if (!folio_test_private(page_folio(page)) && + !can_split_folio(page_folio(page), NULL)) goto next;
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); @@ -3110,7 +3116,7 @@ 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; @@ -3149,7 +3155,7 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, if (!folio_trylock(folio)) goto next;
- if (!split_folio(folio)) + if (!split_huge_page_to_list_to_order(&folio->page, NULL, new_order)) split++;
folio_unlock(folio); @@ -3174,10 +3180,14 @@ 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) @@ -3206,29 +3216,29 @@ 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/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index b8558c7f1a39..cbb5e6893cbf 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -16,6 +16,7 @@ #include <sys/mount.h> #include <malloc.h> #include <stdbool.h> +#include <time.h> #include "vm_util.h"
uint64_t pagesize; @@ -23,10 +24,12 @@ unsigned int pageshift; uint64_t pmd_pagesize;
#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) @@ -113,7 +116,7 @@ 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) { @@ -203,7 +206,7 @@ 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; @@ -269,7 +272,7 @@ void split_file_backed_thp(void) }
/* split the file-backed THP */ - write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end); + write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, 0);
status = unlink(testfile); if (status) @@ -290,20 +293,232 @@ 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"); + goto err_out_unlink; + } + if (write(*fd, "3", 1) != 1) { + perror("write to drop_caches"); + goto err_out_unlink; + } + close(*fd); + + *fd = open(testfile, O_RDWR); + if (*fd == -1) { + perror("Failed to open a file at "THP_FS_PATH); + goto err_out_unlink; + } + + *addr = mmap(NULL, fd_size, PROT_READ|PROT_WRITE, MAP_SHARED, *fd, 0); + if (*addr == (char *)-1) { + perror("cannot mmap"); + goto err_out_close; + } + madvise(*addr, fd_size, MADV_HUGEPAGE); + + for (size_t i = 0; i < fd_size; i++) + dummy += *(*addr + i); + + if (!check_huge_file(*addr, fd_size / pmd_pagesize, pmd_pagesize)) { + printf("No pagecache THP generated, please mount a filesystem supporting pagecache THP at "THP_FS_PATH"\n"); + goto err_out_close; + } + return; +err_out_close: + close(*fd); +err_out_unlink: + unlink(testfile); + 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"; + int err = 0; + + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr); + + printf("split %ld kB PMD-mapped 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); + err = EXIT_FAILURE; + goto out; + } + + if (!check_huge_file(addr, 0, pmd_pagesize)) { + printf("Still FilePmdMapped not split\n"); + err = EXIT_FAILURE; + goto out; + } + + printf("done\n"); +out: + close(fd); + unlink(testfile); + if (err) + exit(err); +} + +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"; + int err = 0; + + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr); + + printf("truncate %ld kB PMD-mapped 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); + err = EXIT_FAILURE; + goto out; + } + + if (!check_huge_file(addr, 0, pmd_pagesize)) { + printf("Still FilePmdMapped not split after truncate\n"); + err = EXIT_FAILURE; + goto out; + } + + printf("done\n"); +out: + close(fd); + unlink(testfile); + if (err) + exit(err); +} + +void punch_hole_in_pagecache_thp(size_t fd_size, off_t offset[], off_t len[], + int n, int num_left_thps) +{ + int fd, j; + char *addr; + size_t i; + const char testfile[] = THP_FS_PATH "/test"; + int err = 0; + + create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr); + + for (j = 0; j < n; j++) { + printf("punch a hole to %ld kB PMD-mapped pagecache page at addr: %lx, offset %ld, and len %ld ...\n", + fd_size >> 10, (unsigned long)addr, offset[j], len[j]); + fallocate(fd, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE, offset[j], len[j]); + } + + 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); + err = EXIT_FAILURE; + goto out; + } + continue; + } + if (*(addr + i) != (char)i) { + printf("%lu byte corrupted in the file\n", i); + err = EXIT_FAILURE; + goto out; + } + } + + if (!check_huge_file(addr, num_left_thps, pmd_pagesize)) { + printf("Still FilePmdMapped not split after punch\n"); + goto out; + } + printf("done\n"); +out: + close(fd); + unlink(testfile); + if (err) + exit(err); +} + 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; + offset[1] = 4 * pagesize; + len[0] = 200 * pagesize; + len[1] = 16 * pagesize; + punch_hole_in_pagecache_thp(fd_size, offset, len, 2, 1); + + 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, 1); + return 0; }