On 14 Aug 2025, at 5:16, Wei Yang wrote:
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:
- split_pte_mapped_thp: the test already uses kpageflags to check;
- split_file_backed_thp: no vaddr available.
Signed-off-by: Zi Yan ziy@nvidia.com
.../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?
Oops, these should be in the prior 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_endCurious why not (uint64_t)split_addr + pmd_pagesize?
It is in V1->V2 changelog. split_huge_pages_pid() always step in PAGESIZE to be able to split mremapped PTE-mapped THPs. Using [addr, addr + fd_size) makes the PMD THP be split multiple times. The goal of this test is to check the result of one non-uniform split, so use [split_addr, split_addr + pagesize) to achieve that.
I will add the above to commit message and a comment here.
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.
See above.
-- Best Regards, Yan, Zi