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From: Lance Yang In-Reply-To: <04734f2d-ea1f-487c-b01c-c3d6e1b4a778@lucifer.local> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Queue-Id: CF85B140009 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: ij5u9ujd85c9kz7y76icaog4qg5kejfb X-HE-Tag: 1760492895-534861 X-HE-Meta: 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 9H8IyUyP 4reaNnQnLXDEZanqUqdeMqpHQkHQhjrhdkIMEHLBMbokObzjgnJ8MN2EmJ4swUzAKIu4RFdBk7eExUeCFdiyTsR4azb+Wakx2QGkPodnBg2ZLl/UxF08JXCYRUeyM5vRD4qNToGdi8WX0+N6yeSYGDp6FIiry4psRTxKpXdqFeEk47ywwEzrCEwkDLfgRMDkAO66RvyB5wILPsqqpcqt8diOiGLoeJa00FRgVveJVVTwEntarkBIPVcAZnOBRiMffVb+ou1uD2MwdABlSn8ZSriYU2aEqvhOJEie6WSE8ZAkMUQ1YJV2K6Fh/rM/9U42h1SpgT5XKtJt+zIdngLSDFTnRR6TYM1iDIsSO3SwlA/ld0IgQ8IRcRA/GNcbf9rD5if/I X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/10/15 01:41, Lorenzo Stoakes wrote: > OK so this patch _is_ based on [0] already being applied then? > > I don't see any is_swap_pte() here so presumably so right? > > Can we just respin these series and put them together? Because now I've > reviewed a bunch of stuff in [0], which this series depends upon, and > you're saying we should now review on this instead of that and it's a bit > of a mess. > > Once review here is dealt with can you combine [0] into this series please? Got it, thanks! > > For [0] I would like you to reinstate the is_swap_pte() conditional as > (copiously :) discussed over there. > > [0}: https://lore.kernel.org/all/20251008032657.72406-1-lance.yang@linux.dev/ > > Thanks, Lorenzo > > On Wed, Oct 08, 2025 at 12:37:48PM +0800, Lance Yang wrote: >> From: Lance Yang >> >> As David suggested, the PTE scanning logic in hpage_collapse_scan_pmd() >> and __collapse_huge_page_isolate() was almost duplicated. >> >> This patch cleans things up by moving all the common PTE checking logic >> into a new shared helper, thp_collapse_check_pte(). While at it, we use >> vm_normal_folio() instead of vm_normal_page(). >> >> Suggested-by: David Hildenbrand >> Suggested-by: Dev Jain >> Signed-off-by: Lance Yang >> --- >> mm/khugepaged.c | 243 ++++++++++++++++++++++++++---------------------- >> 1 file changed, 130 insertions(+), 113 deletions(-) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index b5c0295c3414..7116caae1fa4 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -61,6 +61,12 @@ enum scan_result { >> SCAN_PAGE_FILLED, >> }; >> >> +enum pte_check_result { >> + PTE_CHECK_SUCCEED, >> + PTE_CHECK_CONTINUE, >> + PTE_CHECK_FAIL, >> +}; >> + >> #define CREATE_TRACE_POINTS >> #include >> >> @@ -533,62 +539,139 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte, >> } >> } >> >> +/* >> + * thp_collapse_check_pte - Check if a PTE is suitable for THP collapse >> + * @pte: The PTE to check >> + * @vma: The VMA the PTE belongs to >> + * @addr: The virtual address corresponding to this PTE >> + * @foliop: On success, used to return a pointer to the folio >> + * Must be non-NULL >> + * @none_or_zero: Counter for none/zero PTEs. Must be non-NULL >> + * @unmapped: Counter for swap PTEs. Can be NULL if not scanning swaps >> + * @shared: Counter for shared pages. Must be non-NULL >> + * @scan_result: Used to return the failure reason (SCAN_*) on a >> + * PTE_CHECK_FAIL return. Must be non-NULL >> + * @cc: Collapse control settings >> + * >> + * Returns: >> + * PTE_CHECK_SUCCEED - PTE is suitable, proceed with further checks >> + * PTE_CHECK_CONTINUE - Skip this PTE and continue scanning >> + * PTE_CHECK_FAIL - Abort collapse scan >> + */ >> +static inline int thp_collapse_check_pte(pte_t pte, struct vm_area_struct *vma, >> + unsigned long addr, struct folio **foliop, int *none_or_zero, >> + int *unmapped, int *shared, int *scan_result, >> + struct collapse_control *cc) >> +{ >> + struct folio *folio = NULL; >> + >> + if (pte_none(pte) || is_zero_pfn(pte_pfn(pte))) { >> + (*none_or_zero)++; >> + if (!userfaultfd_armed(vma) && >> + (!cc->is_khugepaged || >> + *none_or_zero <= khugepaged_max_ptes_none)) { >> + return PTE_CHECK_CONTINUE; >> + } else { >> + *scan_result = SCAN_EXCEED_NONE_PTE; >> + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); >> + return PTE_CHECK_FAIL; >> + } >> + } else if (!pte_present(pte)) { >> + if (!unmapped) { >> + *scan_result = SCAN_PTE_NON_PRESENT; >> + return PTE_CHECK_FAIL; >> + } >> + >> + if (non_swap_entry(pte_to_swp_entry(pte))) { >> + *scan_result = SCAN_PTE_NON_PRESENT; >> + return PTE_CHECK_FAIL; >> + } >> + >> + (*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(pte)) { >> + *scan_result = SCAN_PTE_UFFD_WP; >> + return PTE_CHECK_FAIL; >> + } >> + return PTE_CHECK_CONTINUE; >> + } else { >> + *scan_result = SCAN_EXCEED_SWAP_PTE; >> + count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); >> + return PTE_CHECK_FAIL; >> + } >> + } else if (pte_uffd_wp(pte)) { >> + /* >> + * Don't collapse the page if any of the small PTEs are >> + * armed with uffd write protection. Here we can also mark >> + * the new huge pmd as write protected if any of the small >> + * ones is marked but that could bring unknown userfault >> + * messages that falls outside of the registered range. >> + * So, just be simple. >> + */ >> + *scan_result = SCAN_PTE_UFFD_WP; >> + return PTE_CHECK_FAIL; >> + } >> + >> + folio = vm_normal_folio(vma, addr, pte); >> + if (unlikely(!folio) || unlikely(folio_is_zone_device(folio))) { >> + *scan_result = SCAN_PAGE_NULL; >> + return PTE_CHECK_FAIL; >> + } >> + >> + if (!folio_test_anon(folio)) { >> + VM_WARN_ON_FOLIO(true, folio); >> + *scan_result = SCAN_PAGE_ANON; >> + return PTE_CHECK_FAIL; >> + } >> + >> + /* >> + * We treat a single page as shared if any part of the THP >> + * is shared. >> + */ >> + if (folio_maybe_mapped_shared(folio)) { >> + (*shared)++; >> + if (cc->is_khugepaged && *shared > khugepaged_max_ptes_shared) { >> + *scan_result = SCAN_EXCEED_SHARED_PTE; >> + count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); >> + return PTE_CHECK_FAIL; >> + } >> + } >> + >> + *foliop = folio; >> + >> + return PTE_CHECK_SUCCEED; >> +} >> + >> static int __collapse_huge_page_isolate(struct vm_area_struct *vma, >> unsigned long start_addr, >> pte_t *pte, >> struct collapse_control *cc, >> struct list_head *compound_pagelist) >> { >> - struct page *page = NULL; >> struct folio *folio = NULL; >> unsigned long addr = start_addr; >> pte_t *_pte; >> int none_or_zero = 0, shared = 0, result = SCAN_FAIL, referenced = 0; >> + int pte_check_res; >> >> for (_pte = pte; _pte < pte + HPAGE_PMD_NR; >> _pte++, addr += PAGE_SIZE) { >> pte_t pteval = ptep_get(_pte); >> - if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { >> - ++none_or_zero; >> - if (!userfaultfd_armed(vma) && >> - (!cc->is_khugepaged || >> - none_or_zero <= khugepaged_max_ptes_none)) { >> - continue; >> - } else { >> - result = SCAN_EXCEED_NONE_PTE; >> - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); >> - goto out; >> - } >> - } else if (!pte_present(pteval)) { >> - result = SCAN_PTE_NON_PRESENT; >> - goto out; >> - } else if (pte_uffd_wp(pteval)) { >> - result = SCAN_PTE_UFFD_WP; >> - goto out; >> - } >> - page = vm_normal_page(vma, addr, pteval); >> - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { >> - result = SCAN_PAGE_NULL; >> - goto out; >> - } >> >> - folio = page_folio(page); >> - if (!folio_test_anon(folio)) { >> - VM_WARN_ON_FOLIO(true, folio); >> - result = SCAN_PAGE_ANON; >> - goto out; >> - } >> + pte_check_res = thp_collapse_check_pte(pteval, vma, addr, >> + &folio, &none_or_zero, NULL, &shared, >> + &result, cc); >> >> - /* See hpage_collapse_scan_pmd(). */ >> - if (folio_maybe_mapped_shared(folio)) { >> - ++shared; >> - if (cc->is_khugepaged && >> - shared > khugepaged_max_ptes_shared) { >> - result = SCAN_EXCEED_SHARED_PTE; >> - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); >> - goto out; >> - } >> - } >> + if (pte_check_res == PTE_CHECK_CONTINUE) >> + continue; >> + else if (pte_check_res == PTE_CHECK_FAIL) >> + goto out; >> >> if (folio_test_large(folio)) { >> struct folio *f; >> @@ -1264,11 +1347,11 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, >> pte_t *pte, *_pte; >> int result = SCAN_FAIL, referenced = 0; >> int none_or_zero = 0, shared = 0; >> - struct page *page = NULL; >> struct folio *folio = NULL; >> unsigned long addr; >> spinlock_t *ptl; >> int node = NUMA_NO_NODE, unmapped = 0; >> + int pte_check_res; >> >> VM_BUG_ON(start_addr & ~HPAGE_PMD_MASK); >> >> @@ -1287,81 +1370,15 @@ static int hpage_collapse_scan_pmd(struct mm_struct *mm, >> for (addr = start_addr, _pte = pte; _pte < pte + HPAGE_PMD_NR; >> _pte++, addr += PAGE_SIZE) { >> pte_t pteval = ptep_get(_pte); >> - if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { >> - ++none_or_zero; >> - if (!userfaultfd_armed(vma) && >> - (!cc->is_khugepaged || >> - none_or_zero <= khugepaged_max_ptes_none)) { >> - continue; >> - } else { >> - result = SCAN_EXCEED_NONE_PTE; >> - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); >> - goto out_unmap; >> - } >> - } else if (!pte_present(pteval)) { >> - if (non_swap_entry(pte_to_swp_entry(pteval))) { >> - result = SCAN_PTE_NON_PRESENT; >> - goto out_unmap; >> - } >> >> - ++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(pteval)) { >> - result = SCAN_PTE_UFFD_WP; >> - goto out_unmap; >> - } >> - continue; >> - } else { >> - result = SCAN_EXCEED_SWAP_PTE; >> - count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); >> - goto out_unmap; >> - } >> - } else if (pte_uffd_wp(pteval)) { >> - /* >> - * Don't collapse the page if any of the small >> - * PTEs are armed with uffd write protection. >> - * Here we can also mark the new huge pmd as >> - * write protected if any of the small ones is >> - * marked but that could bring unknown >> - * userfault messages that falls outside of >> - * the registered range. So, just be simple. >> - */ >> - result = SCAN_PTE_UFFD_WP; >> - goto out_unmap; >> - } >> + pte_check_res = thp_collapse_check_pte(pteval, vma, addr, >> + &folio, &none_or_zero, &unmapped, >> + &shared, &result, cc); >> >> - page = vm_normal_page(vma, addr, pteval); >> - if (unlikely(!page) || unlikely(is_zone_device_page(page))) { >> - result = SCAN_PAGE_NULL; >> - goto out_unmap; >> - } >> - folio = page_folio(page); >> - >> - if (!folio_test_anon(folio)) { >> - VM_WARN_ON_FOLIO(true, folio); >> - result = SCAN_PAGE_ANON; >> + if (pte_check_res == PTE_CHECK_CONTINUE) >> + continue; >> + else if (pte_check_res == PTE_CHECK_FAIL) >> goto out_unmap; >> - } >> - >> - /* >> - * We treat a single page as shared if any part of the THP >> - * is shared. >> - */ >> - if (folio_maybe_mapped_shared(folio)) { >> - ++shared; >> - if (cc->is_khugepaged && >> - shared > khugepaged_max_ptes_shared) { >> - result = SCAN_EXCEED_SHARED_PTE; >> - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); >> - goto out_unmap; >> - } >> - } >> >> /* >> * Record which node the original page is from and save this >> -- >> 2.49.0 >>