The following cleanup reworks all the max_ptes_* handling into helper functions. This increases the code readability and will later be used to implement the mTHP handling of these variables.
With these changes we abstract all the madvise_collapse() special casing (dont respect the sysctls) away from the functions that utilize them. And will later in this series to cleanly restrict mTHP collapses behaviors. Suggested-by: David Hildenbrand <[email protected]> Signed-off-by: Nico Pache <[email protected]> --- mm/khugepaged.c | 114 +++++++++++++++++++++++++++++++++--------------- 1 file changed, 78 insertions(+), 36 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index afac6bc4e76d..f42b55421191 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -348,6 +348,58 @@ static bool pte_none_or_zero(pte_t pte) return pte_present(pte) && is_zero_pfn(pte_pfn(pte)); } +/** + * collapse_max_ptes_none - Calculate maximum allowed empty PTEs for collapse + * @cc: The collapse control struct + * @vma: The vma to check for userfaultfd + * + * If we are not in khugepaged mode use HPAGE_PMD_NR to allow any + * empty page. + * + * Return: Maximum number of empty PTEs allowed for the collapse operation + */ +static unsigned int collapse_max_ptes_none(struct collapse_control *cc, + struct vm_area_struct *vma) +{ + if (vma && userfaultfd_armed(vma)) + return 0; + if (!cc->is_khugepaged) + return HPAGE_PMD_NR; + return khugepaged_max_ptes_none; +} + +/** + * collapse_max_ptes_shared - Calculate maximum allowed shared PTEs for collapse + * @cc: The collapse control struct + * + * If we are not in khugepaged mode use HPAGE_PMD_NR to allow any + * shared page. + * + * Return: Maximum number of shared PTEs allowed for the collapse operation + */ +static unsigned int collapse_max_ptes_shared(struct collapse_control *cc) +{ + if (!cc->is_khugepaged) + return HPAGE_PMD_NR; + return khugepaged_max_ptes_shared; +} + +/** + * collapse_max_ptes_swap - Calculate maximum allowed swap PTEs for collapse + * @cc: The collapse control struct + * + * If we are not in khugepaged mode use HPAGE_PMD_NR to allow any + * swap page. + * + * Return: Maximum number of swap PTEs allowed for the collapse operation + */ +static unsigned int collapse_max_ptes_swap(struct collapse_control *cc) +{ + if (!cc->is_khugepaged) + return HPAGE_PMD_NR; + return khugepaged_max_ptes_swap; +} + int hugepage_madvise(struct vm_area_struct *vma, vm_flags_t *vm_flags, int advice) { @@ -546,21 +598,19 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, pte_t *_pte; int none_or_zero = 0, shared = 0, referenced = 0; enum scan_result result = SCAN_FAIL; + unsigned int max_ptes_none = collapse_max_ptes_none(cc, vma); + unsigned int max_ptes_shared = collapse_max_ptes_shared(cc); for (_pte = pte; _pte < pte + HPAGE_PMD_NR; _pte++, addr += PAGE_SIZE) { pte_t pteval = ptep_get(_pte); if (pte_none_or_zero(pteval)) { - ++none_or_zero; - if (!userfaultfd_armed(vma) && - (!cc->is_khugepaged || - none_or_zero <= khugepaged_max_ptes_none)) { - continue; - } else { + if (++none_or_zero > max_ptes_none) { result = SCAN_EXCEED_NONE_PTE; count_vm_event(THP_SCAN_EXCEED_NONE_PTE); goto out; } + continue; } if (!pte_present(pteval)) { result = SCAN_PTE_NON_PRESENT; @@ -591,9 +641,7 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, /* See collapse_scan_pmd(). */ if (folio_maybe_mapped_shared(folio)) { - ++shared; - if (cc->is_khugepaged && - shared > khugepaged_max_ptes_shared) { + if (++shared > max_ptes_shared) { result = SCAN_EXCEED_SHARED_PTE; count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); goto out; @@ -1270,6 +1318,9 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, unsigned long addr; spinlock_t *ptl; int node = NUMA_NO_NODE, unmapped = 0; + unsigned int max_ptes_none = collapse_max_ptes_none(cc, vma); + unsigned int max_ptes_shared = collapse_max_ptes_shared(cc); + unsigned int max_ptes_swap = collapse_max_ptes_swap(cc); VM_BUG_ON(start_addr & ~HPAGE_PMD_MASK); @@ -1294,36 +1345,29 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, pte_t pteval = ptep_get(_pte); if (pte_none_or_zero(pteval)) { - ++none_or_zero; - if (!userfaultfd_armed(vma) && - (!cc->is_khugepaged || - none_or_zero <= khugepaged_max_ptes_none)) { - continue; - } else { + if (++none_or_zero > max_ptes_none) { result = SCAN_EXCEED_NONE_PTE; count_vm_event(THP_SCAN_EXCEED_NONE_PTE); goto out_unmap; } + continue; } if (!pte_present(pteval)) { - ++unmapped; - if (!cc->is_khugepaged || - unmapped <= khugepaged_max_ptes_swap) { - /* - * Always be strict with uffd-wp - * enabled swap entries. Please see - * comment below for pte_uffd_wp(). - */ - if (pte_swp_uffd_wp_any(pteval)) { - result = SCAN_PTE_UFFD_WP; - goto out_unmap; - } - continue; - } else { + if (++unmapped > max_ptes_swap) { result = SCAN_EXCEED_SWAP_PTE; count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); goto out_unmap; } + /* + * Always be strict with uffd-wp + * enabled swap entries. Please see + * comment below for pte_uffd_wp(). + */ + if (pte_swp_uffd_wp_any(pteval)) { + result = SCAN_PTE_UFFD_WP; + goto out_unmap; + } + continue; } if (pte_uffd_wp(pteval)) { /* @@ -1366,9 +1410,7 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, * is shared. */ if (folio_maybe_mapped_shared(folio)) { - ++shared; - if (cc->is_khugepaged && - shared > khugepaged_max_ptes_shared) { + if (++shared > max_ptes_shared) { result = SCAN_EXCEED_SHARED_PTE; count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); goto out_unmap; @@ -2329,6 +2371,8 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, int present, swap; int node = NUMA_NO_NODE; enum scan_result result = SCAN_SUCCEED; + unsigned int max_ptes_none = collapse_max_ptes_none(cc, NULL); + unsigned int max_ptes_swap = collapse_max_ptes_swap(cc); present = 0; swap = 0; @@ -2341,8 +2385,7 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, if (xa_is_value(folio)) { swap += 1 << xas_get_order(&xas); - if (cc->is_khugepaged && - swap > khugepaged_max_ptes_swap) { + if (swap > max_ptes_swap) { result = SCAN_EXCEED_SWAP_PTE; count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); break; @@ -2413,8 +2456,7 @@ static enum scan_result collapse_scan_file(struct mm_struct *mm, cc->progress += HPAGE_PMD_NR; if (result == SCAN_SUCCEED) { - if (cc->is_khugepaged && - present < HPAGE_PMD_NR - khugepaged_max_ptes_none) { + if (present < HPAGE_PMD_NR - max_ptes_none) { result = SCAN_EXCEED_NONE_PTE; count_vm_event(THP_SCAN_EXCEED_NONE_PTE); } else { -- 2.53.0
