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

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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: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reviewed-by: Naoya 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joonsoo Kim 2014-01-21 15:49:46 -08:00 committed by Linus Torvalds
parent 0f843c6ac3
commit faecd8dd85
1 changed files with 20 additions and 8 deletions
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28
mm/rmap.c
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@ -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);