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.

Link: https://lkml.kernel.org/r/dc903b378d1e2d26bbbe85409ab9d009631f175c.1651056365.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/rmap.c b/mm/rmap.c
index 829b2f9486c6ed3e3d0ce4fa01fce953ebbe2a68..f73a62c5b180db6f15bab33af8b6c16025fa66be 100644 (file)
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1525,13 +1525,7 @@ 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
@@ -1541,22 +1535,31 @@ 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));
@@ -1879,13 +1882,7 @@ 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
@@ -1895,22 +1892,31 @@ 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));