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mm, thp: do not queue fully unmapped pages for deferred split

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Adding fully unmapped pages into deferred split queue is not productive:
these pages are about to be freed or they are pinned and cannot be split
anyway.

Link: http://lkml.kernel.org/r/20190913091849.11151-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2019-11-30 17:57:15 -08:00 committed by Linus Torvalds
parent 74d4a5797b
commit f1fe80d4ae
1 changed files with 10 additions and 4 deletions
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14
mm/rmap.c
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@ -1292,12 +1292,20 @@ static void page_remove_anon_compound_rmap(struct page *page)
if (TestClearPageDoubleMap(page)) { if (TestClearPageDoubleMap(page)) {
/* /*
* Subpages can be mapped with PTEs too. Check how many of * Subpages can be mapped with PTEs too. Check how many of
* themi are still mapped. * them are still mapped.
*/ */
for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) { for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
if (atomic_add_negative(-1, &page[i]._mapcount)) if (atomic_add_negative(-1, &page[i]._mapcount))
nr++; nr++;
} }
/*
* Queue the page for deferred split if at least one small
* page of the compound page is unmapped, but at least one
* small page is still mapped.
*/
if (nr && nr < HPAGE_PMD_NR)
deferred_split_huge_page(page);
} else { } else {
nr = HPAGE_PMD_NR; nr = HPAGE_PMD_NR;
} }
@ -1305,10 +1313,8 @@ static void page_remove_anon_compound_rmap(struct page *page)
if (unlikely(PageMlocked(page))) if (unlikely(PageMlocked(page)))
clear_page_mlock(page); clear_page_mlock(page);
if (nr) { if (nr)
__mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr); __mod_node_page_state(page_pgdat(page), NR_ANON_MAPPED, -nr);
deferred_split_huge_page(page);
}
} }
/** /**