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Howlett" , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jonathan Corbet , Shuah Khan Subject: Re: [PATCH v4 3/7] mm/khugepaged: introduce a count_collapse_event() helper Message-ID: References: <20260811-khugepaged_pte_refactor-v4-0-ddac39d61c4a@linux.dev> <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev> X-Rspam-User: X-Stat-Signature: rr1rnrtyqysoomt5nrcq9zht5j8hdfsq X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 288CBC0008 X-HE-Tag: 1786966497-795090 X-HE-Meta: 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 M6FOIetS bFNpuZRzeDsgYN90//byo+ui4LQgTpnR0cyTExa8MKAV062fDUnno4t867crhceH5VEyMWRt2FATqbyUdvXOzgJZzS0M3fiVADMLaQMX5sTfqn9+chszJ8YLl/C5IOCtmlcd8XNxOv9Lu45ir8GsT7IeH+2mpHQkD8YtK6BjANQbtLOd8D19HSaXvxo22mniHwTM4pRYckNK5HjW8RViyKV0gZXGq1hlcC+i56K7igKtSdIsj/LxJ/WrnuYqWk6i34+DPmZ6ltHxu4971uzxOWTL6p7x4Q11fe5lDCDiW7gbMx7VkHHczt07dFVzgJGxKmq6X5++f1LHsjiKwZf62gJEAUw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Aug 11, 2026 at 06:48:35AM -0600, Nico Pache (Red Hat) wrote: > Provide a simple helper function to help reduce a often used, and > duplicate pattern across the khugepaged code. > > When collapsing to a PMD we need to record a vm_event and the mTHP_stat > event. When doing mTHP collapse we only update the mTHP stat. > > Reviewed-by: Baolin Wang > Acked-by: David Hildenbrand (Arm) > Acked-by: Usama Arif > Signed-off-by: Nico Pache (Red Hat) LGTM so: Reviewed-by: Lorenzo Stoakes (ARM) > --- > mm/khugepaged.c | 42 +++++++++++++++++++++--------------------- > 1 file changed, 21 insertions(+), 21 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 8babd4c97db6..cae510aa2914 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -688,6 +688,14 @@ static inline bool folio_pte_referenced(struct folio *folio, > return pte_young(pteval) || mmu_notifier_test_young(vma->vm_mm, addr); > } > > +static void count_collapse_event(unsigned int order, enum vm_event_item vm_event, > + enum mthp_stat_item mthp_event) Add a comment! Lol no only joking ;) > +{ > + if (is_pmd_order(order)) > + count_vm_event(vm_event); > + count_mthp_stat(order, mthp_event); > +} > + > static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > unsigned long start_addr, pte_t *pte, struct collapse_control *cc, > unsigned int order, struct list_head *compound_pagelist) > @@ -708,9 +716,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > if (pte_none_or_zero(pteval)) { > if (++none_or_zero > max_ptes_none) { > result = SCAN_EXCEED_NONE_PTE; > - if (is_pmd_order(order)) > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_NONE); > + count_collapse_event(order, THP_SCAN_EXCEED_NONE_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_NONE); > goto out; > } > continue; > @@ -752,9 +759,8 @@ static enum scan_result __collapse_huge_page_isolate(struct vm_area_struct *vma, > */ > if (++shared > max_ptes_shared) { > result = SCAN_EXCEED_SHARED_PTE; > - if (is_pmd_order(order)) > - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_EXCEED_SHARED); > + count_collapse_event(order, THP_SCAN_EXCEED_SHARED_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SHARED); > goto out; > } > } > @@ -1264,15 +1270,12 @@ static enum scan_result alloc_charge_folio(struct folio **foliop, struct mm_stru > folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask); > if (!folio) { > *foliop = NULL; > - if (is_pmd_order(order)) > - count_vm_event(THP_COLLAPSE_ALLOC_FAILED); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC_FAILED); > + count_collapse_event(order, THP_COLLAPSE_ALLOC_FAILED, > + MTHP_STAT_COLLAPSE_ALLOC_FAILED); > return SCAN_ALLOC_HUGE_PAGE_FAIL; > } > > - if (is_pmd_order(order)) > - count_vm_event(THP_COLLAPSE_ALLOC); > - count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC); > + count_collapse_event(order, THP_COLLAPSE_ALLOC, MTHP_STAT_COLLAPSE_ALLOC); > > if (unlikely(mem_cgroup_charge(folio, mm, gfp))) { > folio_put(folio); > @@ -1662,9 +1665,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (pte_none_or_zero(pteval)) { > if (++none_or_zero > max_ptes_none) { > result = SCAN_EXCEED_NONE_PTE; > - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_NONE); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_NONE_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_NONE); > goto out_unmap; > } > continue; > @@ -1672,9 +1674,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (!pte_present(pteval)) { > if (++unmapped > max_ptes_swap) { > result = SCAN_EXCEED_SWAP_PTE; > - count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_SWAP); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SWAP_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SWAP); > goto out_unmap; > } > /* > @@ -1731,9 +1732,8 @@ static enum scan_result collapse_scan_pmd(struct mm_struct *mm, > if (folio_maybe_mapped_shared(folio)) { > if (++shared > max_ptes_shared) { > result = SCAN_EXCEED_SHARED_PTE; > - count_vm_event(THP_SCAN_EXCEED_SHARED_PTE); > - count_mthp_stat(HPAGE_PMD_ORDER, > - MTHP_STAT_COLLAPSE_EXCEED_SHARED); > + count_collapse_event(HPAGE_PMD_ORDER, THP_SCAN_EXCEED_SHARED_PTE, > + MTHP_STAT_COLLAPSE_EXCEED_SHARED); > goto out_unmap; > } > } > > -- > 2.55.0 > -- Cheers, Lorenzo