The patch titled
Subject: mm: khugepaged: don't have to put being freed page back to lru
has been added to the -mm tree. Its filename is
mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
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------------------------------------------------------
From: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Subject: mm: khugepaged: don't have to put being freed page back to lru
When khugepaged successfully isolated and copied data from old page to
collapsed THP, the old page is about to be freed if its last mapcount is
gone. So putting the page back to lru sounds not that productive in this
case since the page might be isolated by vmscan but it can't be reclaimed
by vmscan since it can't be unmapped by try_to_unmap() at all.
Actually if khugepaged is the last user of this page so it can be freed
directly. So, clearing active and unevictable flags, unlocking and
dropping refcount from isolate instead of calling putback_lru_page().
Link: http://lkml.kernel.org/r/1588279279-61908-2-git-send-email-yang.shi@xxxxxxxxxxxxxxxxx
Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
--- a/mm/khugepaged.c~mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru
+++ a/mm/khugepaged.c
@@ -559,10 +559,18 @@ void __khugepaged_exit(struct mm_struct
static void release_pte_page(struct page *page)
{
mod_node_page_state(page_pgdat(page),
- NR_ISOLATED_ANON + page_is_file_lru(page),
- -compound_nr(page));
- unlock_page(page);
- putback_lru_page(page);
+ NR_ISOLATED_ANON + page_is_file_lru(page), -compound_nr(page));
+
+ if (total_mapcount(page)) {
+ unlock_page(page);
+ putback_lru_page(page);
+ } else {
+ ClearPageActive(page);
+ ClearPageUnevictable(page);
+ unlock_page(page);
+ /* Drop refcount from isolate */
+ put_page(page);
+ }
}
static void release_pte_pages(pte_t *pte, pte_t *_pte,
@@ -771,8 +779,6 @@ static void __collapse_huge_page_copy(pt
} else {
src_page = pte_page(pteval);
copy_user_highpage(page, src_page, address, vma);
- if (!PageCompound(src_page))
- release_pte_page(src_page);
/*
* ptl mostly unnecessary, but preempt has to
* be disabled to update the per-cpu stats
@@ -786,6 +792,8 @@ static void __collapse_huge_page_copy(pt
pte_clear(vma->vm_mm, address, _pte);
page_remove_rmap(src_page, false);
spin_unlock(ptl);
+ if (!PageCompound(src_page))
+ release_pte_page(src_page);
free_page_and_swap_cache(src_page);
}
}
_
Patches currently in -mm which might be from yang.shi@xxxxxxxxxxxxxxxxx are
mm-khugepaged-add-exceed_max_ptes_-helpers.patch
mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
mm-thp-dont-need-drain-lru-cache-when-splitting-and-mlocking-thp.patch
