Commit faecd8dd authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
Browse files

mm/rmap: factor lock function out of rmap_walk_anon() 



When we traverse anon_vma, we need to take a read-side anon_lock.  But
there is subtle difference in the situation so that we can't use same
method to take a lock in each cases.  Therefore, we need to make
rmap_walk_anon() taking difference lock function.

This patch is the first step, factoring lock function for anon_lock out
of rmap_walk_anon().  It will be used in case of removing migration
entry and in default of rmap_walk_anon().

Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: default avatarNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0f843c6a

mm/rmap.c

+20 −8
Original line number Diff line number Diff line
@@ -1684,6 +1684,24 @@ void __put_anon_vma(struct anon_vma *anon_vma) 
}



#ifdef CONFIG_MIGRATION

static struct anon_vma *rmap_walk_anon_lock(struct page *page)

{

	struct anon_vma *anon_vma;



	/*

	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()

	 * because that depends on page_mapped(); but not all its usages

	 * are holding mmap_sem. Users without mmap_sem are required to

	 * take a reference count to prevent the anon_vma disappearing

	 */

	anon_vma = page_anon_vma(page);

	if (!anon_vma)

		return NULL;



	anon_vma_lock_read(anon_vma);

	return anon_vma;

}



/*

 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():

 * Called by migrate.c to remove migration ptes, but might be used more later.
@@ -1696,16 +1714,10 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, 
	struct anon_vma_chain *avc;

	int ret = SWAP_AGAIN;



	/*

	 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()

	 * because that depends on page_mapped(); but not all its usages

	 * are holding mmap_sem. Users without mmap_sem are required to

	 * take a reference count to prevent the anon_vma disappearing

	 */

	anon_vma = page_anon_vma(page);

	anon_vma = rmap_walk_anon_lock(page);

	if (!anon_vma)

		return ret;

	anon_vma_lock_read(anon_vma);



	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {

		struct vm_area_struct *vma = avc->vma;

		unsigned long address = vma_address(page, vma);

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