From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
The base scheme is the same as for anonymous pages, but we walk by
mapping->i_mmap rather then anon_vma->rb_root.
__split_huge_page_refcount() has been tunned a bit: we need to transfer
PG_swapbacked to tail pages.
Splitting mapped pages haven't tested at all, since we cannot mmap()
file-backed huge pages yet.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 71 +++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 59 insertions(+), 12 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 46a44ac..ac0dc80 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1637,24 +1637,25 @@ static void __split_huge_page_refcount(struct page *page)
*/
page_tail->_mapcount = page->_mapcount;
- BUG_ON(page_tail->mapping);
page_tail->mapping = page->mapping;
-
page_tail->index = page->index + i;
page_nid_xchg_last(page_tail, page_nid_last(page));
- BUG_ON(!PageAnon(page_tail));
BUG_ON(!PageUptodate(page_tail));
BUG_ON(!PageDirty(page_tail));
- BUG_ON(!PageSwapBacked(page_tail));
lru_add_page_tail(page, page_tail, lruvec);
}
atomic_sub(tail_count, &page->_count);
BUG_ON(atomic_read(&page->_count) <= 0);
- __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
- __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
+ if (PageAnon(page)) {
+ __mod_zone_page_state(zone, NR_ANON_TRANSPARENT_HUGEPAGES, -1);
+ __mod_zone_page_state(zone, NR_ANON_PAGES, HPAGE_PMD_NR);
+ } else {
+ __mod_zone_page_state(zone, NR_FILE_TRANSPARENT_HUGEPAGES, -1);
+ __mod_zone_page_state(zone, NR_FILE_PAGES, HPAGE_PMD_NR);
+ }
ClearPageCompound(page);
compound_unlock(page);
@@ -1754,7 +1755,7 @@ static int __split_huge_page_map(struct page *page,
}
/* must be called with anon_vma->root->rwsem held */
-static void __split_huge_page(struct page *page,
+static void __split_anon_huge_page(struct page *page,
struct anon_vma *anon_vma)
{
int mapcount, mapcount2;
@@ -1801,14 +1802,11 @@ static void __split_huge_page(struct page *page,
BUG_ON(mapcount != mapcount2);
}
-int split_huge_page(struct page *page)
+static int split_anon_huge_page(struct page *page)
{
struct anon_vma *anon_vma;
int ret = 1;
- BUG_ON(is_huge_zero_pfn(page_to_pfn(page)));
- BUG_ON(!PageAnon(page));
-
/*
* The caller does not necessarily hold an mmap_sem that would prevent
* the anon_vma disappearing so we first we take a reference to it
@@ -1826,7 +1824,7 @@ int split_huge_page(struct page *page)
goto out_unlock;
BUG_ON(!PageSwapBacked(page));
- __split_huge_page(page, anon_vma);
+ __split_anon_huge_page(page, anon_vma);
count_vm_event(THP_SPLIT);
BUG_ON(PageCompound(page));
@@ -1837,6 +1835,55 @@ out:
return ret;
}
+static int split_file_huge_page(struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+ struct vm_area_struct *vma;
+ int mapcount, mapcount2;
+
+ BUG_ON(!PageHead(page));
+ BUG_ON(PageTail(page));
+
+ mutex_lock(&mapping->i_mmap_mutex);
+ mapcount = 0;
+ vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+ unsigned long addr = vma_address(page, vma);
+ mapcount += __split_huge_page_splitting(page, vma, addr);
+ }
+
+ if (mapcount != page_mapcount(page))
+ printk(KERN_ERR "mapcount %d page_mapcount %d\n",
+ mapcount, page_mapcount(page));
+ BUG_ON(mapcount != page_mapcount(page));
+
+ __split_huge_page_refcount(page);
+
+ mapcount2 = 0;
+ vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
+ unsigned long addr = vma_address(page, vma);
+ mapcount2 += __split_huge_page_map(page, vma, addr);
+ }
+
+ if (mapcount != mapcount2)
+ printk(KERN_ERR "mapcount %d mapcount2 %d page_mapcount %d\n",
+ mapcount, mapcount2, page_mapcount(page));
+ BUG_ON(mapcount != mapcount2);
+ count_vm_event(THP_SPLIT);
+ mutex_unlock(&mapping->i_mmap_mutex);
+ return 0;
+}
+
+int split_huge_page(struct page *page)
+{
+ BUG_ON(is_huge_zero_pfn(page_to_pfn(page)));
+
+ if (PageAnon(page))
+ return split_anon_huge_page(page);
+ else
+ return split_file_huge_page(page);
+}
+
#define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE)
int hugepage_madvise(struct vm_area_struct *vma,
--
1.7.10.4
--
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