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From: wang lian In-Reply-To: <20250812155512.926011-3-ziy@nvidia.com> Date: Wed, 13 Aug 2025 11:38:40 +0800 Cc: Wei Yang , Baolin Wang , David Hildenbrand , linux-mm@kvack.org, Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Content-Transfer-Encoding: quoted-printable Message-Id: References: <20250812155512.926011-1-ziy@nvidia.com> <20250812155512.926011-3-ziy@nvidia.com> To: Zi Yan X-Mailer: Apple Mail (2.3826.600.51.1.1) > On Aug 12, 2025, at 23:55, Zi Yan wrote: >=20 > The helper gathers an folio order statistics of folios within a = virtual > address range and checks it against a given order list. It aims to = provide > a more precise folio order check instead of just checking the = existence of > PMD folios. >=20 > Signed-off-by: Zi Yan > --- > .../selftests/mm/split_huge_page_test.c | 4 +- > tools/testing/selftests/mm/vm_util.c | 173 ++++++++++++++++++ > tools/testing/selftests/mm/vm_util.h | 7 + > 3 files changed, 181 insertions(+), 3 deletions(-) >=20 > diff --git a/tools/testing/selftests/mm/split_huge_page_test.c = b/tools/testing/selftests/mm/split_huge_page_test.c > index 5d07b0b89226..63ac82f0b9e0 100644 > --- a/tools/testing/selftests/mm/split_huge_page_test.c > +++ b/tools/testing/selftests/mm/split_huge_page_test.c > @@ -34,8 +34,6 @@ uint64_t pmd_pagesize; > #define PID_FMT_OFFSET "%d,0x%lx,0x%lx,%d,%d" > #define PATH_FMT "%s,0x%lx,0x%lx,%d" >=20 > -#define PFN_MASK ((1UL<<55)-1) > -#define KPF_THP (1UL<<22) > #define GET_ORDER(nr_pages) (31 - __builtin_clz(nr_pages)) >=20 > int is_backed_by_thp(char *vaddr, int pagemap_file, int = kpageflags_file) > @@ -49,7 +47,7 @@ int is_backed_by_thp(char *vaddr, int pagemap_file, = int kpageflags_file) >=20 > if (kpageflags_file) { > pread(kpageflags_file, &page_flags, = sizeof(page_flags), > - (paddr & PFN_MASK) * = sizeof(page_flags)); > + PAGEMAP_PFN(paddr) * = sizeof(page_flags)); >=20 > return !!(page_flags & KPF_THP); > } > diff --git a/tools/testing/selftests/mm/vm_util.c = b/tools/testing/selftests/mm/vm_util.c > index 6a239aa413e2..4d952d1bc96d 100644 > --- a/tools/testing/selftests/mm/vm_util.c > +++ b/tools/testing/selftests/mm/vm_util.c > @@ -338,6 +338,179 @@ int detect_hugetlb_page_sizes(size_t sizes[], = int max) > return count; > } >=20 > +static int get_pfn_flags(unsigned long pfn, int kpageflags_fd, = uint64_t *flags) > +{ > + size_t count; > + > + count =3D pread(kpageflags_fd, flags, sizeof(*flags), > + pfn * sizeof(*flags)); > + > + if (count !=3D sizeof(*flags)) > + return -1; > + > + return 0; > +} > + > +static int get_page_flags(char *vaddr, int pagemap_fd, int = kpageflags_fd, > + uint64_t *flags) > +{ > + unsigned long pfn; > + > + pfn =3D pagemap_get_pfn(pagemap_fd, vaddr); > + /* > + * Treat non-present page as a page without any flag, so that > + * gather_folio_orders() just record the current folio order. > + */ > + if (pfn =3D=3D -1UL) { > + *flags =3D 0; > + return 1; > + } > + > + if (get_pfn_flags(pfn, kpageflags_fd, flags)) > + return -1; > + > + return 0; > +} > + > +/* > + * gather_folio_orders - scan through [vaddr_start, len) and record = folio orders > + * @vaddr_start: start vaddr > + * @len: range length > + * @pagemap_fd: file descriptor to /proc//pagemap > + * @kpageflags_fd: file descriptor to /proc/kpageflags > + * @orders: output folio order array > + * @nr_orders: folio order array size > + * > + * gather_folio_orders() scan through [vaddr_start, len) and check = all folios > + * within the range and record their orders. All order-0 pages will = be recorded. > + * Non-present vaddr is skipped. > + * > + * > + * Return: 0 - no error, -1 - unhandled cases > + */ > +static int gather_folio_orders(char *vaddr_start, size_t len, > + int pagemap_fd, int kpageflags_fd, > + int orders[], int nr_orders) > +{ > + uint64_t page_flags =3D 0; > + int cur_order =3D -1; > + char *vaddr; > + > + if (!pagemap_fd || !kpageflags_fd) > + return -1; > + if (nr_orders <=3D 0) > + return -1; > + > + for (vaddr =3D vaddr_start; vaddr < vaddr_start + len;) { > + char *next_folio_vaddr; > + int status; > + > + status =3D get_page_flags(vaddr, pagemap_fd, = kpageflags_fd, > + &page_flags); > + if (status < 0) > + return -1; > + > + /* skip non present vaddr */ > + if (status =3D=3D 1) { > + vaddr +=3D psize(); > + continue; > + } > + > + /* all order-0 pages with possible false postive (non = folio) */ > + if (!(page_flags & (KPF_COMPOUND_HEAD | = KPF_COMPOUND_TAIL))) { > + orders[0]++; > + vaddr +=3D psize(); > + continue; > + } > + > + /* skip non thp compound pages */ > + if (!(page_flags & KPF_THP)) { > + vaddr +=3D psize(); > + continue; > + } > + > + /* vpn points to part of a THP at this point */ > + if (page_flags & KPF_COMPOUND_HEAD) > + cur_order =3D 1; > + else { > + /* not a head nor a tail in a THP? */ > + if (!(page_flags & KPF_COMPOUND_TAIL)) > + return -1; > + > + vaddr +=3D psize(); > + continue; > + } > + > + next_folio_vaddr =3D vaddr + (1UL << (cur_order + = pshift())); > + > + if (next_folio_vaddr >=3D vaddr_start + len) > + break; > + > + while ((status =3D get_page_flags(next_folio_vaddr, = pagemap_fd, > + kpageflags_fd, > + &page_flags)) >=3D 0) { > + /* > + * non present vaddr, next compound head page, = or > + * order-0 page > + */ > + if (status =3D=3D 1 || > + (page_flags & KPF_COMPOUND_HEAD) || > + !(page_flags & (KPF_COMPOUND_HEAD | = KPF_COMPOUND_TAIL))) { > + if (cur_order < nr_orders) { > + orders[cur_order]++; > + cur_order =3D -1; > + vaddr =3D next_folio_vaddr; > + } > + break; > + } > + > + /* not a head nor a tail in a THP? */ > + if (!(page_flags & KPF_COMPOUND_TAIL)) > + return -1; > + > + cur_order++; > + next_folio_vaddr =3D vaddr + (1UL << (cur_order = + pshift())); > + } > + > + if (status < 0) > + return status; > + } > + if (cur_order > 0 && cur_order < nr_orders) > + orders[cur_order]++; > + return 0; > +} > + > +int check_folio_orders(char *vaddr_start, size_t len, int pagemap_fd, > + int kpageflags_fd, int orders[], int nr_orders) > +{ > + int *vaddr_orders; > + int status; > + int i; > + > + vaddr_orders =3D (int *)malloc(sizeof(int) * nr_orders); > + > + if (!vaddr_orders) > + ksft_exit_fail_msg("Cannot allocate memory for = vaddr_orders"); > + > + memset(vaddr_orders, 0, sizeof(int) * nr_orders); > + status =3D gather_folio_orders(vaddr_start, len, pagemap_fd, > + kpageflags_fd, vaddr_orders, = nr_orders); > + if (status) > + goto out; > + > + status =3D 0; Nit. It seems redundant. Would you consider removing it for a bit more conciseness? This doesn't block my approval, of course. Reviewed-by: wang lian > + for (i =3D 0; i < nr_orders; i++) > + if (vaddr_orders[i] !=3D orders[i]) { > + ksft_print_msg("order %d: expected: %d got = %d\n", i, > + orders[i], vaddr_orders[i]); > + status =3D -1; > + } > + > +out: > + free(vaddr_orders); > + return status; > +} > + > /* 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 1843ad48d32b..02e3f1e7065b 100644 > --- a/tools/testing/selftests/mm/vm_util.h > +++ b/tools/testing/selftests/mm/vm_util.h > @@ -18,6 +18,11 @@ > #define PM_SWAP BIT_ULL(62) > #define PM_PRESENT BIT_ULL(63) >=20 > +#define KPF_COMPOUND_HEAD BIT_ULL(15) > +#define KPF_COMPOUND_TAIL BIT_ULL(16) > +#define KPF_THP BIT_ULL(22) > + > + > /* > * Ignore the checkpatch warning, we must read from x but don't want = to do > * anything with it in order to trigger a read page fault. We = therefore must use > @@ -85,6 +90,8 @@ bool check_huge_shmem(void *addr, int nr_hpages, = uint64_t hpage_size); > int64_t allocate_transhuge(void *ptr, int pagemap_fd); > unsigned long default_huge_page_size(void); > int detect_hugetlb_page_sizes(size_t sizes[], int max); > +int check_folio_orders(char *vaddr_start, size_t len, int = pagemap_file, > + int kpageflags_file, int orders[], int = nr_orders); >=20 > int uffd_register(int uffd, void *addr, uint64_t len, > bool miss, bool wp, bool minor); > --=20 > 2.47.2 >=20 Best regards, wang lian