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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-07-26 15:25:37 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commitd21b9e57c74ce82ac459e2ec8ce667db9b9da8b0 (patch)
treee35f06f7e07e8bfbc0d1a7d19a52d6ccc87116d4
parentb5072380eb619786990cd9eab3ade05d09ccd89e (diff)
thp: handle file pages in split_huge_pmd()
Splitting THP PMD is simple: just unmap it as in DAX case. This way we can avoid memory overhead on page table allocation to deposit. It's probably a good idea to try to allocation page table with GFP_ATOMIC in __split_huge_pmd_locked() to avoid refaulting the area, but clearing pmd should be good enough for now. Unlike DAX, we also remove the page from rmap and drop reference. pmd_young() is transfered to PageReferenced(). Link: http://lkml.kernel.org/r/1466021202-61880-15-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>
-rw-r--r--mm/huge_memory.c12
1 files changed, 10 insertions, 2 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index d8ccd245947d..e6725c5c5a62 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2987,10 +2987,18 @@ static void __split_huge_pmd_locked(struct vm_area_struct *vma, pmd_t *pmd,
count_vm_event(THP_SPLIT_PMD);
- if (vma_is_dax(vma)) {
- pmd_t _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
+ if (!vma_is_anonymous(vma)) {
+ _pmd = pmdp_huge_clear_flush_notify(vma, haddr, pmd);
if (is_huge_zero_pmd(_pmd))
put_huge_zero_page();
+ if (vma_is_dax(vma))
+ return;
+ page = pmd_page(_pmd);
+ if (!PageReferenced(page) && pmd_young(_pmd))
+ SetPageReferenced(page);
+ page_remove_rmap(page, true);
+ put_page(page);
+ add_mm_counter(mm, MM_FILEPAGES, -HPAGE_PMD_NR);
return;
} else if (is_huge_zero_pmd(*pmd)) {
return __split_huge_zero_page_pmd(vma, haddr, pmd);