[PATCH 14/18] mm, hugetlb: clean-up error handling in hugetlb_cow()

[Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>]

Current code include 'Caller expects lock to be held' in every error path.
We can clean-up it as we do error handling in one place.

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

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 255bd9e..683fd38 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2516,6 +2516,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
 	struct hstate *h = hstate_vma(vma);
 	struct page *old_page, *new_page;
 	int use_reserve, outside_reserve = 0;
+	int ret = 0;
 	unsigned long mmun_start;	/* For mmu_notifiers */
 	unsigned long mmun_end;		/* For mmu_notifiers */
 
@@ -2537,11 +2538,8 @@ retry_avoidcopy:
 
 	use_reserve = vma_has_reserves(h, vma, address);
 	if (use_reserve == -ENOMEM) {
-		page_cache_release(old_page);
-
-		/* Caller expects lock to be held */
-		spin_lock(&mm->page_table_lock);
-		return VM_FAULT_OOM;
+		ret = VM_FAULT_OOM;
+		goto out_old_page;
 	}
 
 	/*
@@ -2588,9 +2586,8 @@ retry_avoidcopy:
 			WARN_ON_ONCE(1);
 		}
 
-		/* Caller expects lock to be held */
-		spin_lock(&mm->page_table_lock);
-		return VM_FAULT_SIGBUS;
+		ret = VM_FAULT_SIGBUS;
+		goto out_lock;
 	}
 
 	/*
@@ -2598,11 +2595,8 @@ retry_avoidcopy:
 	 * 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;
+		ret = VM_FAULT_OOM;
+		goto out_new_page;
 	}
 
 	copy_user_huge_page(new_page, old_page, address, vma,
@@ -2630,12 +2624,15 @@ retry_avoidcopy:
 	}
 	spin_unlock(&mm->page_table_lock);
 	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+
+out_new_page:
 	page_cache_release(new_page);
+out_old_page:
 	page_cache_release(old_page);
-
+out_lock:
 	/* Caller expects lock to be held */
 	spin_lock(&mm->page_table_lock);
-	return 0;
+	return ret;
 }
 
 /* Return the pagecache page at a given address within a VMA */
-- 
1.7.9.5

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