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Subject[PATCH 4.19 03/34] mm/rmap: use page_not_mapped in try_to_unmap()
Date
From: Miaohe Lin <linmiaohe@huawei.com>

[ Upstream commit b7e188ec98b1644ff70a6d3624ea16aadc39f5e0 ]

page_mapcount_is_zero() calculates accurately how many mappings a hugepage
has in order to check against 0 only. This is a waste of cpu time. We
can do this via page_not_mapped() to save some possible atomic_read
cycles. Remove the function page_mapcount_is_zero() as it's not used
anymore and move page_not_mapped() above try_to_unmap() to avoid
identifier undeclared compilation error.

Link: https://lkml.kernel.org/r/20210130084904.35307-1-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/rmap.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 69ce68616cbf..70872d5b203c 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1682,9 +1682,9 @@ static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
return is_vma_temporary_stack(vma);
}

-static int page_mapcount_is_zero(struct page *page)
+static int page_not_mapped(struct page *page)
{
- return !total_mapcount(page);
+ return !page_mapped(page);
}

/**
@@ -1702,7 +1702,7 @@ bool try_to_unmap(struct page *page, enum ttu_flags flags)
struct rmap_walk_control rwc = {
.rmap_one = try_to_unmap_one,
.arg = (void *)flags,
- .done = page_mapcount_is_zero,
+ .done = page_not_mapped,
.anon_lock = page_lock_anon_vma_read,
};

@@ -1726,11 +1726,6 @@ bool try_to_unmap(struct page *page, enum ttu_flags flags)
return !page_mapcount(page) ? true : false;
}

-static int page_not_mapped(struct page *page)
-{
- return !page_mapped(page);
-}
-
/**
* try_to_munlock - try to munlock a page
* @page: the page to be munlocked
--
2.30.2


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