From: "Kiryl Shutsemau (Meta)" <[email protected]> For orders below PMD, check_huge() counts folios of the requested order in the range and compares the count with nr_hpages. The count does not say where the folios are. A folio mapped at the wrong alignment, or split across two windows, counts the same as one placed where khugepaged would put it.
Count aligned windows backed by a single folio of that order instead. is_range_backed_by_order() already does it for one window. Move it up and use it. All callers pass PMD-aligned ranges, so the windows line up. The PMD case is unchanged. This is preparation for using check_huge() for the collapse_order cases in khugepaged.c. Assisted-by: LLM Signed-off-by: Kiryl Shutsemau (Meta) <[email protected]> --- tools/testing/selftests/mm/vm_util.c | 131 +++++++++++++-------------- 1 file changed, 61 insertions(+), 70 deletions(-) diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c index e284e378d806..0a4b85e29e14 100644 --- a/tools/testing/selftests/mm/vm_util.c +++ b/tools/testing/selftests/mm/vm_util.c @@ -17,7 +17,6 @@ #define MAX_LINE_LENGTH 500 #define PAGEMAP_PATH "/proc/self/pagemap" #define KPAGEFLAGS_PATH "/proc/kpageflags" -#define MAX_NR_ORDERS 20 unsigned int __page_size; unsigned int __page_shift; @@ -397,34 +396,72 @@ char *__get_smap_entry(void *addr, const char *pattern, char *buf, size_t len) return entry; } -static bool check_large_folios(int pagemap_fd, int kpageflags_fd, - void *addr, size_t len, int nr_hpages, - uint64_t hpage_size) +/** + * is_range_backed_by_order() - check that a range is backed by @order folios + * @start: start of the range, a multiple of the folio size + * @len: length of the range in bytes, a multiple of the folio size + * @order: the folio order to check for + * @pagemap_fd: open /proc/<pid>/pagemap of the range's owner + * @kpageflags_fd: open /proc/kpageflags + * + * Every folio-sized, folio-aligned part of the range must map one folio of + * @order, head to tail, with the head at the start of the part. A part + * backed by several smaller folios fails, and so does a folio mapped off + * its natural alignment. + * + * Returns: true if the whole range is backed that way, false otherwise. + */ +bool is_range_backed_by_order(char *start, size_t len, int order, + int pagemap_fd, int kpageflags_fd) { - int order = 0, pagesize = getpagesize(); - unsigned int nr_pages = hpage_size / pagesize; - int orders[MAX_NR_ORDERS], status; - bool ret = false; + const unsigned long nr_pages = 1UL << order; + const size_t folio_size = nr_pages * psize(); + char *vaddr; - if (!nr_pages) - ksft_exit_fail_msg("invalid hugepage size\n"); + if ((uintptr_t)start % folio_size || len % folio_size) + return false; - order = 31 - __builtin_clz(nr_pages); - if (!order || order >= MAX_NR_ORDERS) - ksft_exit_fail_msg("invalid order\n"); + for (vaddr = start; vaddr < start + len; vaddr += folio_size) { + const unsigned long pfn = pagemap_get_pfn(pagemap_fd, vaddr); + unsigned long i; - memset(orders, 0, sizeof(int) * MAX_NR_ORDERS); + /* Not present, or a tail page */ + if (pfn == -1UL || pfn % nr_pages) + return false; - status = gather_folio_orders(addr, len, pagemap_fd, - kpageflags_fd, orders, MAX_NR_ORDERS); - if (status) - goto out; + for (i = 1; i < nr_pages; i++) { + char *page = vaddr + i * psize(); - if (orders[order] == nr_hpages) - ret = true; + if (pagemap_get_pfn(pagemap_fd, page) != pfn + i) + return false; + } -out: - return ret; + if (!is_backed_by_folio(vaddr, order, pagemap_fd, kpageflags_fd)) + return false; + } + + return true; +} + +/* + * How many hpage_size-aligned windows of the range are one folio of that + * size each, with the folio's head at the window start. A folio mapped off + * its alignment or split across two windows counts for neither. + */ +static int count_windows_at_order(char *start, size_t len, uint64_t hpage_size, + int pagemap_fd, int kpageflags_fd) +{ + const int order = sz2ord(hpage_size, psize()); + int nr_windows = 0; + char *addr; + + for (addr = start; addr + hpage_size <= start + len; addr += hpage_size) { + if (is_range_backed_by_order(addr, hpage_size, order, + pagemap_fd, kpageflags_fd)) + nr_windows++; + } + + return nr_windows; } enum check_huge_type { @@ -471,8 +508,8 @@ static bool __check_huge(void *addr, size_t len, int nr_hpages, kpageflags_fd = kpageflags_fd_get(); if (!check_pmd_mapping && - !check_large_folios(pagemap_fd, kpageflags_fd, - addr, len, nr_hpages, hpage_size)) + nr_hpages != count_windows_at_order(start, len, hpage_size, + pagemap_fd, kpageflags_fd)) return false; for (; start < end; start += scan_mapping_size) { @@ -608,52 +645,6 @@ bool is_backed_by_folio(char *vaddr, int order, int pagemap_fd, ksft_exit_fail_msg("Failed to get folio info\n"); } -/** - * is_range_backed_by_order() - check that a range is backed by @order folios - * @start: start of the range, a multiple of the folio size - * @len: length of the range in bytes, a multiple of the folio size - * @order: the folio order to check for - * @pagemap_fd: open /proc/<pid>/pagemap of the range's owner - * @kpageflags_fd: open /proc/kpageflags - * - * Every folio-sized, folio-aligned part of the range must map one folio of - * @order, head to tail, with the head at the start of the part. A part - * backed by several smaller folios fails, and so does a folio mapped off - * its natural alignment. - * - * Returns: true if the whole range is backed that way, false otherwise. - */ -bool is_range_backed_by_order(char *start, size_t len, int order, - int pagemap_fd, int kpageflags_fd) -{ - const unsigned long nr_pages = 1UL << order; - const size_t folio_size = nr_pages * psize(); - char *vaddr; - - if ((uintptr_t)start % folio_size || len % folio_size) - return false; - - for (vaddr = start; vaddr < start + len; vaddr += folio_size) { - const unsigned long pfn = pagemap_get_pfn(pagemap_fd, vaddr); - unsigned long i; - - /* Not present, or a tail page */ - if (pfn == -1UL || pfn % nr_pages) - return false; - - for (i = 1; i < nr_pages; i++) { - char *page = vaddr + i * psize(); - - if (pagemap_get_pfn(pagemap_fd, page) != pfn + i) - return false; - } - - if (!is_backed_by_folio(vaddr, order, pagemap_fd, kpageflags_fd)) - return false; - } - - return true; -} #define TRACEFS_ROOT "/sys/kernel/tracing" -- 2.54.0
