From: "Kiryl Shutsemau (Meta)" <[email protected]> The khugepaged selftest is about to gain mTHP collapse coverage, which needs to verify that a VA range is backed by a folio of a given order. split_huge_page_test.c already has the building block for that: is_backed_by_folio() classifies the folio backing a page via /proc/kpageflags compound head/tail flags.
Move it into vm_util so other tests can use it. No functional change. Assisted-by: Claude-Code:claude-opus-5 Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> --- .../selftests/mm/split_huge_page_test.c | 62 ------------------- tools/testing/selftests/mm/vm_util.c | 62 +++++++++++++++++++ tools/testing/selftests/mm/vm_util.h | 2 + 3 files changed, 64 insertions(+), 62 deletions(-) diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c index 32b991472f74..9b3885bd001b 100644 --- a/tools/testing/selftests/mm/split_huge_page_test.c +++ b/tools/testing/selftests/mm/split_huge_page_test.c @@ -42,68 +42,6 @@ const char *kpageflags_proc = "/proc/kpageflags"; int pagemap_fd; int kpageflags_fd; -static bool is_backed_by_folio(char *vaddr, int order, int pagemap_fd, - int kpageflags_fd) -{ - const uint64_t folio_head_flags = KPF_THP | KPF_COMPOUND_HEAD; - const uint64_t folio_tail_flags = KPF_THP | KPF_COMPOUND_TAIL; - const unsigned long nr_pages = 1UL << order; - unsigned long pfn_head; - uint64_t pfn_flags; - unsigned long pfn; - unsigned long i; - - pfn = pagemap_get_pfn(pagemap_fd, vaddr); - - /* non present page */ - if (pfn == -1UL) - return false; - - if (pageflags_get(pfn, kpageflags_fd, &pfn_flags)) - goto fail; - - /* check for order-0 pages */ - if (!order) { - if (pfn_flags & (folio_head_flags | folio_tail_flags)) - return false; - return true; - } - - /* non THP folio */ - if (!(pfn_flags & KPF_THP)) - return false; - - pfn_head = pfn & ~(nr_pages - 1); - - if (pageflags_get(pfn_head, kpageflags_fd, &pfn_flags)) - goto fail; - - /* head PFN has no compound_head flag set */ - if ((pfn_flags & folio_head_flags) != folio_head_flags) - return false; - - /* check all tail PFN flags */ - for (i = 1; i < nr_pages; i++) { - if (pageflags_get(pfn_head + i, kpageflags_fd, &pfn_flags)) - goto fail; - if ((pfn_flags & folio_tail_flags) != folio_tail_flags) - return false; - } - - /* - * check the PFN after this folio, but if its flags cannot be obtained, - * assume this folio has the expected order - */ - if (pageflags_get(pfn_head + nr_pages, kpageflags_fd, &pfn_flags)) - return true; - - /* If we find another tail page, then the folio is larger. */ - return (pfn_flags & folio_tail_flags) != folio_tail_flags; -fail: - ksft_exit_fail_msg("Failed to get folio info\n"); - return false; -} - static int vaddr_pageflags_get(char *vaddr, int pagemap_fd, int kpageflags_fd, uint64_t *flags) { diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index ef1ea11981a7..343a15e25a9f 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -303,6 +303,68 @@ int pageflags_get(unsigned long pfn, int kpageflags_fd, uint64_t *flags) return 0; } +bool is_backed_by_folio(char *vaddr, int order, int pagemap_fd, + int kpageflags_fd) +{ + const uint64_t folio_head_flags = KPF_THP | KPF_COMPOUND_HEAD; + const uint64_t folio_tail_flags = KPF_THP | KPF_COMPOUND_TAIL; + const unsigned long nr_pages = 1UL << order; + unsigned long pfn_head; + uint64_t pfn_flags; + unsigned long pfn; + unsigned long i; + + pfn = pagemap_get_pfn(pagemap_fd, vaddr); + + /* non present page */ + if (pfn == -1UL) + return false; + + if (pageflags_get(pfn, kpageflags_fd, &pfn_flags)) + goto fail; + + /* check for order-0 pages */ + if (!order) { + if (pfn_flags & (folio_head_flags | folio_tail_flags)) + return false; + return true; + } + + /* non THP folio */ + if (!(pfn_flags & KPF_THP)) + return false; + + pfn_head = pfn & ~(nr_pages - 1); + + if (pageflags_get(pfn_head, kpageflags_fd, &pfn_flags)) + goto fail; + + /* head PFN has no compound_head flag set */ + if ((pfn_flags & folio_head_flags) != folio_head_flags) + return false; + + /* check all tail PFN flags */ + for (i = 1; i < nr_pages; i++) { + if (pageflags_get(pfn_head + i, kpageflags_fd, &pfn_flags)) + goto fail; + if ((pfn_flags & folio_tail_flags) != folio_tail_flags) + return false; + } + + /* + * check the PFN after this folio, but if its flags cannot be obtained, + * assume this folio has the expected order + */ + if (pageflags_get(pfn_head + nr_pages, kpageflags_fd, &pfn_flags)) + return true; + + /* If we find another tail page, then the folio is larger. */ + return (pfn_flags & folio_tail_flags) != folio_tail_flags; +fail: + ksft_exit_fail_msg("Failed to get folio info\n"); + return false; +} + /* If `ioctls' non-NULL, the allowed ioctls will be returned into the var */ int uffd_register_with_ioctls(int uffd, void *addr, uint64_t len, bool miss, bool wp, bool minor, uint64_t *ioctls) diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h index 7799154b67ee..5eb90e0d1d13 100644 --- a/tools/testing/selftests/mm/vm_util.h +++ b/tools/testing/selftests/mm/vm_util.h @@ -95,6 +95,8 @@ bool check_huge_file(void *addr, int nr_hpages, uint64_t hpage_size); bool check_huge_shmem(void *addr, int nr_hpages, uint64_t hpage_size); int64_t allocate_transhuge(void *ptr, int pagemap_fd); int pageflags_get(unsigned long pfn, int kpageflags_fd, uint64_t *flags); +bool is_backed_by_folio(char *vaddr, int order, int pagemap_fd, + int kpageflags_fd); int uffd_register(int uffd, void *addr, uint64_t len, bool miss, bool wp, bool minor); -- 2.54.0
