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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-07-26 15:25:51 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commitbaa355fd331424526e742d41d9b90d5f9d10f716 (patch)
tree762004078f781ba9fd053186dcb7d9925d3c41bd /mm/gup.c
parent37f9f5595c26d3cb644ca2fab83dc4c4db119f9f (diff)
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thp: file pages support for split_huge_page()
Basic scheme is the same as for anon THP. Main differences: - File pages are on radix-tree, so we have head->_count offset by HPAGE_PMD_NR. The count got distributed to small pages during split. - mapping->tree_lock prevents non-lockless access to pages under split over radix-tree; - Lockless access is prevented by setting the head->_count to 0 during split; - After split, some pages can be beyond i_size. We drop them from radix-tree. - We don't setup migration entries. Just unmap pages. It helps handling cases when i_size is in the middle of the page: no need handle unmap pages beyond i_size manually. Link: http://lkml.kernel.org/r/1466021202-61880-20-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 9671e29f8ffd..547741f5f7a7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -288,6 +288,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
ret = split_huge_page(page);
unlock_page(page);
put_page(page);
+ if (pmd_none(*pmd))
+ return no_page_table(vma, flags);
}
return ret ? ERR_PTR(ret) :