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For each folio in the target region that is larger than the scheme's target_order, split it via split_folio_to_order(). This supports both anonymous and file-backed (e.g. tmpfs/shmem) folios, covering KVM guest memory backed by THP tmpfs. Signed-off-by: Lian Wang Signed-off-by: Lian Wang --- mm/damon/vaddr.c | 80 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c index 98a87609376b..a177703f7e0a 100644 --- a/mm/damon/vaddr.c +++ b/mm/damon/vaddr.c @@ -944,6 +944,83 @@ static unsigned long damos_va_collapse(struct damon_target *target, return applied; } +static unsigned long damos_va_split(struct damon_target *target, + struct damon_region *r, struct damos *s, + unsigned long *sz_filter_passed) +{ + unsigned long addr, end, chunk_sz; + unsigned int target_order = s->target_order; + unsigned long applied = 0; + struct mm_struct *mm; + struct vm_area_struct *vma; + struct folio *folio; + struct folio_walk fw; + + mm = damon_get_mm(target); + if (!mm) + return 0; + + chunk_sz = PAGE_SIZE << HPAGE_PMD_ORDER; + addr = ALIGN_DOWN(r->ar.start, chunk_sz); + end = ALIGN(r->ar.end, chunk_sz); + if (end < addr) + goto out_mmput; + + while (addr < end) { + unsigned long folio_sz; + + if (addr + chunk_sz < addr) + break; + + mmap_read_lock(mm); + vma = find_vma(mm, addr); + + if (!vma || addr < vma->vm_start || + vma->vm_flags & (VM_HUGETLB | VM_MIXEDMAP)) + goto unlock; + + folio = folio_walk_start(&fw, vma, addr, 0); + if (!folio) + goto unlock; + + folio_sz = PAGE_SIZE << folio_order(folio); + + if (folio_order(folio) > target_order) { + if (!folio_trylock(folio)) { + folio_walk_end(&fw, vma); + goto unlock; + } + folio_get(folio); + folio_walk_end(&fw, vma); + + if (!split_folio_to_order(folio, target_order)) + applied += folio_sz; + + folio_unlock(folio); + folio_put(folio); + *sz_filter_passed += folio_sz; + addr += folio_sz; + } else { + folio_walk_end(&fw, vma); + *sz_filter_passed += chunk_sz; + addr += chunk_sz; + } + mmap_read_unlock(mm); + cond_resched(); + continue; + +unlock: + *sz_filter_passed += chunk_sz; + addr += chunk_sz; + mmap_read_unlock(mm); + cond_resched(); + } + +out_mmput: + mmput(mm); + return applied; +} + static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx, struct damon_target *t, struct damon_region *r, struct damos *scheme, unsigned long *sz_filter_passed) @@ -977,6 +1054,9 @@ static unsigned long damon_va_apply_scheme(struct damon_ctx *ctx, return damos_va_migrate(t, r, scheme, sz_filter_passed); case DAMOS_STAT: return damos_va_stat(t, r, scheme, sz_filter_passed); + case DAMOS_SPLIT: + return damos_va_split(t, r, scheme, + sz_filter_passed); default: /* * DAMOS actions that are not yet supported by 'vaddr'.