linux-kernel - [PATCH v2 17/20] mm, hugetlb: move up anon_vma

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Date:	Fri,  9 Aug 2013 18:26:35 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Rik van Riel <riel@...hat.com>, Mel Gorman <mgorman@...e.de>,
	Michal Hocko <mhocko@...e.cz>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hughd@...gle.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	David Gibson <david@...son.dropbear.id.au>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Joonsoo Kim <js1304@...il.com>,
	Wanpeng Li <liwanp@...ux.vnet.ibm.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Hillf Danton <dhillf@...il.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v2 17/20] mm, hugetlb: move up anon_vma_prepare()

If we fail with a allocated hugepage, we need some effort to recover
properly. So, it is better not to allocate a hugepage as much as possible.
So move up anon_vma_prepare() which can be failed in OOM situation.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 2372f75..7e9a651 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2520,6 +2520,17 @@ retry_avoidcopy:
 	spin_unlock(&mm->page_table_lock);
 
 	/*
+	 * When the original hugepage is shared one, it does not have
+	 * anon_vma prepared.
+	 */
+	if (unlikely(anon_vma_prepare(vma))) {
+		page_cache_release(old_page);
+		/* Caller expects lock to be held */
+		spin_lock(&mm->page_table_lock);
+		return VM_FAULT_OOM;
+	}
+
+	/*
 	 * If the process that created a MAP_PRIVATE mapping is about to
 	 * perform a COW due to a shared page count, attempt to satisfy
 	 * the allocation without using the existing reserves. The pagecache
@@ -2578,18 +2589,6 @@ retry_avoidcopy:
 		return VM_FAULT_SIGBUS;
 	}
 
-	/*
-	 * When the original hugepage is shared one, it does not have
-	 * anon_vma prepared.
-	 */
-	if (unlikely(anon_vma_prepare(vma))) {
-		page_cache_release(new_page);
-		page_cache_release(old_page);
-		/* Caller expects lock to be held */
-		spin_lock(&mm->page_table_lock);
-		return VM_FAULT_OOM;
-	}
-
 	copy_user_huge_page(new_page, old_page, address, vma,
 			    pages_per_huge_page(h));
 	__SetPageUptodate(new_page);
-- 
1.7.9.5

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