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Message-Id: <20231018203213.50224-6-vishal.moola@gmail.com>
Date: Wed, 18 Oct 2023 13:32:13 -0700
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
shy828301@...il.com,
"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH v2 5/5] mm/khugepaged: Convert collapse_pte_mapped_thp() to use folios
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 can get the corresponding folio back and try to
operate on the folio instead.
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
mm/khugepaged.c | 45 ++++++++++++++++++++-------------------------
1 file changed, 20 insertions(+), 25 deletions(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d49aa22d99c9..94c1dd09a8a6 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1475,7 +1475,7 @@ 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;
@@ -1508,19 +1508,14 @@ 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 (!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);
@@ -1534,13 +1529,13 @@ 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;
@@ -1565,7 +1560,7 @@ 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;
}
@@ -1580,7 +1575,7 @@ 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))
@@ -1604,7 +1599,7 @@ 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.
*/
@@ -1613,7 +1608,7 @@ 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;
/*
@@ -1632,8 +1627,8 @@ 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 */
@@ -1657,14 +1652,14 @@ 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);
@@ -1672,9 +1667,9 @@ int collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr,
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;
}
--
2.40.1
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