On 13 Aug 2025, at 17:41, Wei Yang wrote:
On Tue, Aug 12, 2025 at 11:55:11AM -0400, Zi Yan wrote:
and rename it to is_backed_by_folio().
is_backed_by_folio() checks if the given vaddr is backed a folio with a given order. It does so by:
- getting the pfn of the vaddr;
- checking kpageflags of the pfn;
if order is greater than 0: 3. checking kpageflags of the head pfn; 4. checking kpageflags of all tail pfns.
pmd_order is added to split_huge_page_test.c and replaces max_order.
Signed-off-by: Zi Yan ziy@nvidia.com
.../selftests/mm/split_huge_page_test.c | 67 +++++++++++++------ tools/testing/selftests/mm/vm_util.c | 2 +- tools/testing/selftests/mm/vm_util.h | 1 + 3 files changed, 48 insertions(+), 22 deletions(-)
diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 63ac82f0b9e0..3aaf783f339f 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -25,6 +25,7 @@ uint64_t pagesize; unsigned int pageshift; uint64_t pmd_pagesize; +unsigned int pmd_order;
#define SPLIT_DEBUGFS "/sys/kernel/debug/split_huge_pages" #define SMAP_PATH "/proc/self/smaps" @@ -36,23 +37,48 @@ uint64_t pmd_pagesize;
#define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages))
-int is_backed_by_thp(char *vaddr, int pagemap_file, int kpageflags_file) +int is_backed_by_folio(char *vaddr, int order, int pagemap_fd, int kpageflags_fd) {
- uint64_t paddr;
- uint64_t page_flags;
- unsigned long pfn_head;
- uint64_t pfn_flags;
- unsigned long pfn;
- unsigned long i;
- if (pagemap_file) {
pread(pagemap_file, &paddr, sizeof(paddr),((long)vaddr >> pageshift) * sizeof(paddr));
- if (!pagemap_fd || !kpageflags_fd)
return 0;The same in patch 2.
Will fix it.
if (kpageflags_file) {pread(kpageflags_file, &page_flags, sizeof(page_flags),PAGEMAP_PFN(paddr) * sizeof(page_flags));
- pfn = pagemap_get_pfn(pagemap_fd, vaddr);
return !!(page_flags & KPF_THP);}
- if (pfn == -1UL)
return 0;- if (get_pfn_flags(pfn, kpageflags_fd, &pfn_flags))
return 0;- if (!order) {
if (pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD | KPF_COMPOUND_TAIL))return 0;return 1;
- return 0;
- if (!(pfn_flags & KPF_THP))
return 0;- pfn_head = pfn & ~((1 << order) - 1);
- if (get_pfn_flags(pfn_head, kpageflags_fd, &pfn_flags))
return 0;- if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_HEAD)))
return 0;- for (i = 1; i < (1UL << order) - 1; i++) {
Do we miss the last tail?
Yes, will fix it.
if (get_pfn_flags(pfn_head + i, kpageflags_fd, &pfn_flags))return 0;if (!(pfn_flags & (KPF_THP | KPF_COMPOUND_TAIL)))return 0;- }
If this folio is larger than order, would it still return 1?
Yes, but it should be good enough for current use. Will add a comment about it.
Thanks for the review.
Best Regards, Yan, Zi