+ mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch added to -mm tree

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Subject: + mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch added to -mm tree
To: iamjoonsoo.kim@xxxxxxx,dhillf@xxxxxxxxx,hughd@xxxxxxxxxx,mgorman@xxxxxxx,mingo@xxxxxxxxxx,n-horiguchi@xxxxxxxxxxxxx,riel@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 04 Dec 2013 14:16:42 -0800


The patch titled
     Subject: mm/rmap: factor lock function out of rmap_walk_anon()
has been added to the -mm tree.  Its filename is
     mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch

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------------------------------------------------------
From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: 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: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Hillf Danton <dhillf@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/rmap.c |   28 ++++++++++++++++++++--------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff -puN mm/rmap.c~mm-rmap-factor-lock-function-out-of-rmap_walk_anon mm/rmap.c
--- a/mm/rmap.c~mm-rmap-factor-lock-function-out-of-rmap_walk_anon
+++ a/mm/rmap.c
@@ -1680,6 +1680,24 @@ void __put_anon_vma(struct anon_vma *ano
 }
 
 #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.
@@ -1692,16 +1710,10 @@ static int rmap_walk_anon(struct page *p
 	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);
_

Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are

mm-rmap-recompute-pgoff-for-huge-page.patch
mm-rmap-factor-nonlinear-handling-out-of-try_to_unmap_file.patch
mm-rmap-factor-lock-function-out-of-rmap_walk_anon.patch
mm-rmap-make-rmap_walk-to-get-the-rmap_walk_control-argument.patch
mm-rmap-extend-rmap_walk_xxx-to-cope-with-different-cases.patch
mm-rmap-use-rmap_walk-in-try_to_unmap.patch
mm-rmap-use-rmap_walk-in-try_to_munlock.patch
mm-rmap-use-rmap_walk-in-page_referenced.patch
mm-rmap-use-rmap_walk-in-page_mkclean.patch

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