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mm/khugepaged: introduce a count_collapse_event() helper

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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.

Link: https://lore.kernel.org/20260811-khugepaged_pte_refactor-v4-3-ddac39d61c4a@linux.dev
Signed-off-by: Nico Pache (Red Hat) <nico.pache@linux.dev>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Usama Arif <usama.arif@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Nico Pache (Red Hat) 2026-08-11 06:48:35 -06:00 committed by Andrew Morton
parent e8122742cf
commit 948ec48e56
1 changed files with 21 additions and 21 deletions
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42
mm/khugepaged.c
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@ -682,6 +682,14 @@ static 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)
{
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)
@ -702,9 +710,8 @@ 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;
@ -746,9 +753,8 @@ 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;
}
}
@ -1258,15 +1264,12 @@ 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);
@ -1656,9 +1659,8 @@ 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;
@ -1666,9 +1668,8 @@ 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;
}
/*
@ -1725,9 +1726,8 @@ 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;
}
}