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mm/huge_memory: separate out the folio part of zap_huge_pmd()

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Place the part of the logic that manipulates counters and possibly updates
the accessed bit of the folio into its own function to make zap_huge_pmd()
more readable.

Also rename flush_needed to is_present as we only require a flush for
present entries.

Additionally add comments as to why we're doing what we're doing with
respect to softleaf entries.

This also lays the ground for further refactoring.

Link: https://lkml.kernel.org/r/6c4db67952f5529da4db102a6149b9050b5dda4e.1774029655.git.ljs@kernel.org
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Lorenzo Stoakes (Oracle) 2026-03-20 18:07:27 +00:00 committed by Andrew Morton
parent 1c6b7ff60b
commit f87854c909
1 changed files with 35 additions and 26 deletions
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61
mm/huge_memory.c
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@ -2402,6 +2402,37 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
mm_dec_nr_ptes(mm);
}
static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma,
pmd_t pmdval, struct folio *folio, bool is_present,
bool *has_deposit)
{
const bool is_device_private = folio_is_device_private(folio);
/* Present and device private folios are rmappable. */
if (is_present || is_device_private)
folio_remove_rmap_pmd(folio, &folio->page, vma);
if (folio_test_anon(folio)) {
*has_deposit = true;
add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
} else {
add_mm_counter(mm, mm_counter_file(folio),
-HPAGE_PMD_NR);
/*
* Use flush_needed to indicate whether the PMD entry
* is present, instead of checking pmd_present() again.
*/
if (is_present && pmd_young(pmdval) &&
likely(vma_has_recency(vma)))
folio_mark_accessed(folio);
}
/* Device private folios are pinned. */
if (is_device_private)
folio_put(folio);
}
/**
* zap_huge_pmd - Zap a huge THP which is of PMD size.
* @tlb: The MMU gather TLB state associated with the operation.
@ -2417,7 +2448,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
bool has_deposit = arch_needs_pgtable_deposit();
struct mm_struct *mm = tlb->mm;
struct folio *folio = NULL;
bool flush_needed = false;
bool is_present = false;
spinlock_t *ptl;
pmd_t orig_pmd;
@ -2446,14 +2477,11 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
if (pmd_present(orig_pmd)) {
folio = pmd_folio(orig_pmd);
flush_needed = true;
folio_remove_rmap_pmd(folio, &folio->page, vma);
is_present = true;
} else if (pmd_is_valid_softleaf(orig_pmd)) {
const softleaf_t entry = softleaf_from_pmd(orig_pmd);
folio = softleaf_to_folio(entry);
if (!thp_migration_supported())
WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
} else {
@ -2461,33 +2489,14 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
goto out;
}
if (folio_test_anon(folio)) {
has_deposit = true;
add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
} else {
add_mm_counter(mm, mm_counter_file(folio),
-HPAGE_PMD_NR);
/*
* Use flush_needed to indicate whether the PMD entry
* is present, instead of checking pmd_present() again.
*/
if (flush_needed && pmd_young(orig_pmd) &&
likely(vma_has_recency(vma)))
folio_mark_accessed(folio);
}
if (folio_is_device_private(folio)) {
folio_remove_rmap_pmd(folio, &folio->page, vma);
folio_put(folio);
}
zap_huge_pmd_folio(mm, vma, orig_pmd, folio, is_present, &has_deposit);
out:
if (has_deposit)
zap_deposited_table(mm, pmd);
spin_unlock(ptl);
if (flush_needed)
if (is_present)
tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
return true;
}