The patch titled
Subject: swap: Deal with PTE mapped THP when unuse PTE
has been added to the -mm tree. Its filename is
mm-rid-swapoff-of-quadratic-complexity-fix-2.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-rid-swapoff-of-quadratic-complexity-fix-2.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-rid-swapoff-of-quadratic-complexity-fix-2.patch
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------------------------------------------------------
From: Huang Ying <ying.huang@xxxxxxxxx>
Subject: swap: Deal with PTE mapped THP when unuse PTE
A PTE swap entry may map to a normal swap slot inside a huge swap cluster.
To free the huge swap cluster and the corresponding THP (transparent huge
page), all PTE swap entry mappings need to be unmapped. The original
implementation only checks current PTE swap entry mapping, this is fixed
via calling try_to_free_swap() instead, which will check all PTE swap
mappings inside the huge swap cluster.
This fix could be folded into the patch: mm, swap: rid swapoff of
quadratic complexity in -mm patchset.
Link: http://lkml.kernel.org/r/20181211084609.19553-2-ying.huang@xxxxxxxxx
Signed-off-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Vineeth Remanan Pillai <vpillai@xxxxxxxxxxxxxxxx>
Cc: Kelley Nielsen <kelleynnn@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/swapfile.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
--- a/mm/swapfile.c~mm-rid-swapoff-of-quadratic-complexity-fix-2
+++ a/mm/swapfile.c
@@ -1853,10 +1853,8 @@ static int unuse_pte_range(struct vm_are
goto out;
}
- if (PageSwapCache(page) && (swap_count(*swap_map) == 0))
- delete_from_swap_cache(compound_head(page));
+ try_to_free_swap(page);
- SetPageDirty(page);
unlock_page(page);
put_page(page);
_
Patches currently in -mm which might be from ying.huang@xxxxxxxxx are
mm-rid-swapoff-of-quadratic-complexity-fix-1.patch
mm-rid-swapoff-of-quadratic-complexity-fix-2.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations.patch
mm-swap-fix-race-between-swapoff-and-some-swap-operations-v6.patch
mm-fix-race-between-swapoff-and-mincore.patch
