Commit b7e188ec authored by Miaohe Lin's avatar Miaohe Lin Committed by Linus Torvalds
Browse files

mm/rmap: use page_not_mapped in try_to_unmap() 

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: default avatarMiaohe Lin <linmiaohe@huawei.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 90aaca85

mm/rmap.c

+3 −8
Original line number Diff line number Diff line
@@ -1736,9 +1736,9 @@ static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) 
	return vma_is_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);

}



/**
@@ -1756,7 +1756,7 @@ 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,

	};
@@ -1780,11 +1780,6 @@ 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