On Tue, Aug 12, 2025 at 11:55:12AM -0400, Zi Yan wrote:
>Instead of just checking the existence of PMD folios before and after folio
>split tests, use check_folio_orders() to check after-split folio orders.
>
>The following tests are not changed:
>1. split_pte_mapped_thp: the test already uses kpageflags to check;
>2. split_file_backed_thp: no vaddr available.
>
>Signed-off-by: Zi Yan <[email protected]>
>---
> .../selftests/mm/split_huge_page_test.c | 85 +++++++++++++------
> 1 file changed, 61 insertions(+), 24 deletions(-)
>
>diff --git a/tools/testing/selftests/mm/split_huge_page_test.c
>b/tools/testing/selftests/mm/split_huge_page_test.c
>index 3aaf783f339f..1ea2c7f22962 100644
>--- a/tools/testing/selftests/mm/split_huge_page_test.c
>+++ b/tools/testing/selftests/mm/split_huge_page_test.c
>@@ -26,6 +26,7 @@ uint64_t pagesize;
> unsigned int pageshift;
> uint64_t pmd_pagesize;
> unsigned int pmd_order;
>+int *expected_orders;
>
> #define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages"
> #define SMAP_PATH "/proc/self/smaps"
>@@ -37,6 +38,11 @@ unsigned int pmd_order;
>
> #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
>
>+const char *pagemap_proc = "/proc/self/pagemap";
>+const char *kpageflags_proc = "/proc/kpageflags";
>+int pagemap_fd;
>+int kpageflags_fd;
>+
> int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, int
> kpageflags_fd)
> {
> unsigned long pfn_head;
>@@ -49,18 +55,21 @@ int is_backed_by_folio(char *vaddr, int order, int
>pagemap_fd, int kpageflags_fd
>
> pfn = pagemap_get_pfn(pagemap_fd, vaddr);
>
>+ /* non present page */
> if (pfn == -1UL)
> return 0;
>
> if (get_pfn_flags(pfn, kpageflags_fd, &pfn_flags))
> return 0;
>
>+ /* check for order-0 pages */
> if (!order) {
> if (pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD |
> KPF_COMPOUND_TAIL))
> return 0;
> return 1;
> }
>
>+ /* non THP folio */
> if (!(pfn_flags & KPF_THP))
> return 0;
>
>@@ -69,9 +78,11 @@ int is_backed_by_folio(char *vaddr, int order, int
>pagemap_fd, int kpageflags_fd
> if (get_pfn_flags(pfn_head, kpageflags_fd, &pfn_flags))
> return 0;
>
>+ /* head PFN has no compound_head flag set */
> if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD)))
> return 0;
>
>+ /* check all tail PFN flags */
> for (i = 1; i < (1UL << order) - 1; i++) {
> if (get_pfn_flags(pfn_head + i, kpageflags_fd, &pfn_flags))
> return 0;
The comment in is_backed_by_folio() is more proper to be in previous patch?
>@@ -198,6 +209,12 @@ void split_pmd_thp_to_order(int order)
> if (one_page[i] != (char)i)
> ksft_exit_fail_msg("%ld byte corrupted\n", i);
>
>+ memset(expected_orders, 0, sizeof(int) * (pmd_order + 1));
>+ expected_orders[order] = 4 << (pmd_order - order);
>+
>+ if (check_folio_orders(one_page, len, pagemap_fd, kpageflags_fd,
>+ expected_orders, (pmd_order + 1)))
>+ ksft_exit_fail_msg("Unexpected THP split\n");
>
> if (!check_huge_anon(one_page, 0, pmd_pagesize))
> ksft_exit_fail_msg("Still AnonHugePages not split\n");
>@@ -212,22 +229,6 @@ void split_pte_mapped_thp(void)
> size_t len = 4 * pmd_pagesize;
> uint64_t thp_size;
> size_t i;
>- const char *pagemap_template = "/proc/%d/pagemap";
>- const char *kpageflags_proc = "/proc/kpageflags";
>- char pagemap_proc[255];
>- int pagemap_fd;
>- int kpageflags_fd;
>-
>- if (snprintf(pagemap_proc, 255, pagemap_template, getpid()) < 0)
>- ksft_exit_fail_msg("get pagemap proc error: %s\n",
>strerror(errno));
>-
>- pagemap_fd = open(pagemap_proc, O_RDONLY);
>- if (pagemap_fd == -1)
>- ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
>-
>- kpageflags_fd = open(kpageflags_proc, O_RDONLY);
>- if (kpageflags_fd == -1)
>- ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
>
> one_page = mmap((void *)(1UL << 30), len, PROT_READ | PROT_WRITE,
> MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
>@@ -285,8 +286,6 @@ void split_pte_mapped_thp(void)
>
> ksft_test_result_pass("Split PTE-mapped huge pages successful\n");
> munmap(one_page, len);
>- close(pagemap_fd);
>- close(kpageflags_fd);
> }
>
> void split_file_backed_thp(int order)
>@@ -489,6 +488,7 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size,
>const char *fs_loc,
> int order, int offset)
> {
> int fd;
>+ char *split_addr;
> char *addr;
> size_t i;
> char testfile[INPUT_MAX];
>@@ -502,14 +502,27 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size,
>const char *fs_loc,
> err = create_pagecache_thp_and_fd(testfile, fd_size, &fd, &addr);
> if (err)
> return;
>+
> err = 0;
>
>- if (offset == -1)
>- write_debugfs(PID_FMT, getpid(), (uint64_t)addr,
>- (uint64_t)addr + fd_size, order);
>- else
>- write_debugfs(PID_FMT_OFFSET, getpid(), (uint64_t)addr,
>- (uint64_t)addr + fd_size, order, offset);
>+ memset(expected_orders, 0, sizeof(int) * (pmd_order + 1));
I am not familiar with split, you change it to split on each pmd_pagesize from
4 pmd_pagesize. Is there any difference?
>+ if (offset == -1) {
>+ for (split_addr = addr; split_addr < addr + fd_size; split_addr
>+= pmd_pagesize)
>+ write_debugfs(PID_FMT, getpid(), (uint64_t)split_addr,
>+ (uint64_t)split_addr + pagesize, order);
^--- here should be vaddr_end
Curious why not (uint64_t)split_addr + pmd_pagesize?
>+
>+ expected_orders[order] = fd_size / (pagesize << order);
>+ } else {
>+ int times = fd_size / pmd_pagesize;
>+
>+ for (split_addr = addr; split_addr < addr + fd_size; split_addr
>+= pmd_pagesize)
>+ write_debugfs(PID_FMT_OFFSET, getpid(),
>(uint64_t)split_addr,
>+ (uint64_t)split_addr + pagesize, order,
>offset);
As above.
>+
>+ for (i = order + 1; i < pmd_order; i++)
>+ expected_orders[i] = times;
>+ expected_orders[order] = 2 * times;
>+ }
>
> for (i = 0; i < fd_size; i++)
> if (*(addr + i) != (char)i) {
>@@ -518,6 +531,13 @@ void split_thp_in_pagecache_to_order_at(size_t fd_size,
>const char *fs_loc,
> goto out;
> }
>
>+ if (check_folio_orders(addr, fd_size, pagemap_fd, kpageflags_fd,
>+ expected_orders, (pmd_order + 1))) {
>+ ksft_print_msg("Unexpected THP split\n");
>+ err = 1;
>+ goto out;
>+ }
>+
> if (!check_huge_file(addr, 0, pmd_pagesize)) {
> ksft_print_msg("Still FilePmdMapped not split\n");
> err = EXIT_FAILURE;
>@@ -569,9 +589,22 @@ int main(int argc, char **argv)
>
> nr_pages = pmd_pagesize / pagesize;
> pmd_order = GET_ORDER(nr_pages);
>+
>+ expected_orders = (int *)malloc(sizeof(int) * (pmd_order + 1));
>+ if (!expected_orders)
>+ ksft_exit_fail_msg("Fail to allocate memory: %s\n",
>strerror(errno));
>+
> tests = 2 + (pmd_order - 1) + (2 * pmd_order) + (pmd_order - 1) * 4 + 2;
> ksft_set_plan(tests);
>
>+ pagemap_fd = open(pagemap_proc, O_RDONLY);
>+ if (pagemap_fd == -1)
>+ ksft_exit_fail_msg("read pagemap: %s\n", strerror(errno));
>+
>+ kpageflags_fd = open(kpageflags_proc, O_RDONLY);
>+ if (kpageflags_fd == -1)
>+ ksft_exit_fail_msg("read kpageflags: %s\n", strerror(errno));
>+
> fd_size = 2 * pmd_pagesize;
>
> split_pmd_zero_pages();
>@@ -596,6 +629,10 @@ int main(int argc, char **argv)
> split_thp_in_pagecache_to_order_at(fd_size, fs_loc, i,
> offset);
> cleanup_thp_fs(fs_loc, created_tmp);
>
>+ close(pagemap_fd);
>+ close(kpageflags_fd);
>+ free(expected_orders);
>+
> ksft_finished();
>
> return 0;
>--
>2.47.2
--
Wei Yang
Help you, Help me
