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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-01-15 16:54:17 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-01-15 17:56:32 -0800
commit9a982250f773cc8c76f1eee68a770b7cbf2faf78 (patch)
treede5a99423acf031b98510369d4dc2cf4b6e496ac /mm/rmap.c
parent248db92da13f25073e7ebbd5fb95615aafd771d1 (diff)
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thp: introduce deferred_split_huge_page()
Currently we don't split huge page on partial unmap. It's not an ideal situation. It can lead to memory overhead. Furtunately, we can detect partial unmap on page_remove_rmap(). But we cannot call split_huge_page() from there due to locking context. It's also counterproductive to do directly from munmap() codepath: in many cases we will hit this from exit(2) and splitting the huge page just to free it up in small pages is not what we really want. The patch introduce deferred_split_huge_page() which put the huge page into queue for splitting. The splitting itself will happen when we get memory pressure via shrinker interface. The page will be dropped from list on freeing through compound page destructor. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Tested-by: Sasha Levin <sasha.levin@oracle.com> Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Jerome Marchand <jmarchan@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Steve Capper <steve.capper@linaro.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
-rw-r--r--mm/rmap.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index fc707df92ede..84271cc39d1e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1282,8 +1282,10 @@ static void page_remove_anon_compound_rmap(struct page *page)
nr = HPAGE_PMD_NR;
}
- if (nr)
+ if (nr) {
__mod_zone_page_state(page_zone(page), NR_ANON_PAGES, -nr);
+ deferred_split_huge_page(page);
+ }
}
/**
@@ -1318,6 +1320,9 @@ void page_remove_rmap(struct page *page, bool compound)
if (unlikely(PageMlocked(page)))
clear_page_mlock(page);
+ if (PageTransCompound(page))
+ deferred_split_huge_page(compound_head(page));
+
/*
* It would be tidy to reset the PageAnon mapping here,
* but that might overwrite a racing page_add_anon_rmap