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mm/khugepaged: convert collapse_pte_mapped_thp() to use folios

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This removes 2 calls to compound_head() and helps convert khugepaged to
use folios throughout.

Previously, if the address passed to collapse_pte_mapped_thp()
corresponded to a tail page, the scan would fail immediately. Using
filemap_lock_folio() we get the corresponding folio back and try to
operate on the folio instead.

Link: https://lkml.kernel.org/r/20231020183331.10770-6-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Rik van Riel <riel@surriel.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Vishal Moola (Oracle) 2023-10-20 11:33:31 -07:00 committed by Andrew Morton
parent b455f39d22
commit 98b32d296d
1 changed files with 20 additions and 25 deletions
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45
mm/khugepaged.c
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@ -1477,7 +1477,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
bool notified = false;
unsigned long haddr = addr & HPAGE_PMD_MASK;
struct vm_area_struct *vma = vma_lookup(mm, haddr);
struct page *hpage;
struct folio *folio;
pte_t *start_pte, *pte;
pmd_t *pmd, pgt_pmd;
spinlock_t *pml = NULL, *ptl;
@ -1510,19 +1510,14 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
if (userfaultfd_wp(vma))
return SCAN_PTE_UFFD_WP;
hpage = find_lock_page(vma->vm_file->f_mapping,
folio = filemap_lock_folio(vma->vm_file->f_mapping,
linear_page_index(vma, haddr));
if (!hpage)
if (IS_ERR(folio))
return SCAN_PAGE_NULL;
if (!PageHead(hpage)) {
result = SCAN_FAIL;
goto drop_hpage;
}
if (compound_order(hpage) != HPAGE_PMD_ORDER) {
if (folio_order(folio) != HPAGE_PMD_ORDER) {
result = SCAN_PAGE_COMPOUND;
goto drop_hpage;
goto drop_folio;
}
result = find_pmd_or_thp_or_none(mm, haddr, &pmd);
@ -1536,13 +1531,13 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
*/
goto maybe_install_pmd;
default:
goto drop_hpage;
goto drop_folio;
}
result = SCAN_FAIL;
start_pte = pte_offset_map_lock(mm, pmd, haddr, &ptl);
if (!start_pte) /* mmap_lock + page lock should prevent this */
goto drop_hpage;
goto drop_folio;
/* step 1: check all mapped PTEs are to the right huge page */
for (i = 0, addr = haddr, pte = start_pte;
@ -1567,7 +1562,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
* Note that uprobe, debugger, or MAP_PRIVATE may change the
* page table, but the new page will not be a subpage of hpage.
*/
if (hpage + i != page)
if (folio_page(folio, i) != page)
goto abort;
}
@ -1582,7 +1577,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
* page_table_lock) ptl nests inside pml. The less time we hold pml,
* the better; but userfaultfd's mfill_atomic_pte() on a private VMA
* inserts a valid as-if-COWed PTE without even looking up page cache.
* So page lock of hpage does not protect from it, so we must not drop
* So page lock of folio does not protect from it, so we must not drop
* ptl before pgt_pmd is removed, so uffd private needs pml taken now.
*/
if (userfaultfd_armed(vma) && !(vma->vm_flags & VM_SHARED))
@ -1606,7 +1601,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
continue;
/*
* We dropped ptl after the first scan, to do the mmu_notifier:
* page lock stops more PTEs of the hpage being faulted in, but
* page lock stops more PTEs of the folio being faulted in, but
* does not stop write faults COWing anon copies from existing
* PTEs; and does not stop those being swapped out or migrated.
*/
@ -1615,7 +1610,7 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
goto abort;
}
page = vm_normal_page(vma, addr, ptent);
if (hpage + i != page)
if (folio_page(folio, i) != page)
goto abort;
/*
@ -1634,8 +1629,8 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
/* step 3: set proper refcount and mm_counters. */
if (nr_ptes) {
page_ref_sub(hpage, nr_ptes);
add_mm_counter(mm, mm_counter_file(hpage), -nr_ptes);
folio_ref_sub(folio, nr_ptes);
add_mm_counter(mm, mm_counter_file(&folio->page), -nr_ptes);
}
/* step 4: remove empty page table */
@ -1659,14 +1654,14 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
maybe_install_pmd:
/* step 5: install pmd entry */
result = install_pmd
? set_huge_pmd(vma, haddr, pmd, hpage)
? set_huge_pmd(vma, haddr, pmd, &folio->page)
: SCAN_SUCCEED;
goto drop_hpage;
goto drop_folio;
abort:
if (nr_ptes) {
flush_tlb_mm(mm);
page_ref_sub(hpage, nr_ptes);
add_mm_counter(mm, mm_counter_file(hpage), -nr_ptes);
folio_ref_sub(folio, nr_ptes);
add_mm_counter(mm, mm_counter_file(&folio->page), -nr_ptes);
}
if (start_pte)
pte_unmap_unlock(start_pte, ptl);
@ -1674,9 +1669,9 @@ abort:
spin_unlock(pml);
if (notified)
mmu_notifier_invalidate_range_end(&range);
drop_hpage:
unlock_page(hpage);
put_page(hpage);
drop_folio:
folio_unlock(folio);
folio_put(folio);
return result;
}