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Date: Wed, 27 Apr 2022 18:52:07 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: akpm@...ux-foundation.org, mike.kravetz@...cle.com
Cc: almasrymina@...gle.com, songmuchun@...edance.com,
baolin.wang@...ux.alibaba.com, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] mm: rmap: Use flush_cache_range() to flush cache for hugetlb pages
Now we will use flush_cache_page() to flush cache for anonymous hugetlb
pages when unmapping or migrating a hugetlb page mapping, but the
flush_cache_page() only handles a PAGE_SIZE range on some architectures
(like arm32, arc and so on), which will cause potential cache issues.
Thus change to use flush_cache_range() to cover the whole size of a
hugetlb page.
Signed-off-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
---
mm/rmap.c | 90 ++++++++++++++++++++++++++++++++++-----------------------------
1 file changed, 48 insertions(+), 42 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index 4f0d115..6fdd198 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1528,13 +1528,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
anon_exclusive = folio_test_anon(folio) &&
PageAnonExclusive(subpage);
- if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {
- /*
- * To call huge_pmd_unshare, i_mmap_rwsem must be
- * held in write mode. Caller needs to explicitly
- * do this outside rmap routines.
- */
- VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
+ if (folio_test_hugetlb(folio)) {
/*
* huge_pmd_unshare may unmap an entire PMD page.
* There is no way of knowing exactly which PMDs may
@@ -1544,22 +1538,31 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
*/
flush_cache_range(vma, range.start, range.end);
- if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
- flush_tlb_range(vma, range.start, range.end);
- mmu_notifier_invalidate_range(mm, range.start,
- range.end);
-
+ if (!folio_test_anon(folio)) {
/*
- * The ref count of the PMD page was dropped
- * which is part of the way map counting
- * is done for shared PMDs. Return 'true'
- * here. When there is no other sharing,
- * huge_pmd_unshare returns false and we will
- * unmap the actual page and drop map count
- * to zero.
+ * To call huge_pmd_unshare, i_mmap_rwsem must be
+ * held in write mode. Caller needs to explicitly
+ * do this outside rmap routines.
*/
- page_vma_mapped_walk_done(&pvmw);
- break;
+ VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
+
+ if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
+ flush_tlb_range(vma, range.start, range.end);
+ mmu_notifier_invalidate_range(mm, range.start,
+ range.end);
+
+ /*
+ * The ref count of the PMD page was dropped
+ * which is part of the way map counting
+ * is done for shared PMDs. Return 'true'
+ * here. When there is no other sharing,
+ * huge_pmd_unshare returns false and we will
+ * unmap the actual page and drop map count
+ * to zero.
+ */
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
}
} else {
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
@@ -1885,13 +1888,7 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
anon_exclusive = folio_test_anon(folio) &&
PageAnonExclusive(subpage);
- if (folio_test_hugetlb(folio) && !folio_test_anon(folio)) {
- /*
- * To call huge_pmd_unshare, i_mmap_rwsem must be
- * held in write mode. Caller needs to explicitly
- * do this outside rmap routines.
- */
- VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
+ if (folio_test_hugetlb(folio)) {
/*
* huge_pmd_unshare may unmap an entire PMD page.
* There is no way of knowing exactly which PMDs may
@@ -1901,22 +1898,31 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
*/
flush_cache_range(vma, range.start, range.end);
- if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
- flush_tlb_range(vma, range.start, range.end);
- mmu_notifier_invalidate_range(mm, range.start,
- range.end);
-
+ if (!folio_test_anon(folio)) {
/*
- * The ref count of the PMD page was dropped
- * which is part of the way map counting
- * is done for shared PMDs. Return 'true'
- * here. When there is no other sharing,
- * huge_pmd_unshare returns false and we will
- * unmap the actual page and drop map count
- * to zero.
+ * To call huge_pmd_unshare, i_mmap_rwsem must be
+ * held in write mode. Caller needs to explicitly
+ * do this outside rmap routines.
*/
- page_vma_mapped_walk_done(&pvmw);
- break;
+ VM_BUG_ON(!(flags & TTU_RMAP_LOCKED));
+
+ if (huge_pmd_unshare(mm, vma, &address, pvmw.pte)) {
+ flush_tlb_range(vma, range.start, range.end);
+ mmu_notifier_invalidate_range(mm, range.start,
+ range.end);
+
+ /*
+ * The ref count of the PMD page was dropped
+ * which is part of the way map counting
+ * is done for shared PMDs. Return 'true'
+ * here. When there is no other sharing,
+ * huge_pmd_unshare returns false and we will
+ * unmap the actual page and drop map count
+ * to zero.
+ */
+ page_vma_mapped_walk_done(&pvmw);
+ break;
+ }
}
} else {
flush_cache_page(vma, address, pte_pfn(*pvmw.pte));
--
1.8.3.1
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