linux-kernel - [PATCH] mm: zbud: fix condition check on allocation size

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Date:	Wed, 17 Jul 2013 23:30:10 +0900
From:	Heesub Shin <heesub.shin@...sung.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Seth Jennings <sjenning@...ux.vnet.ibm.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Dongjun Shin <d.j.shin@...sung.com>,
	Sunae Seo <sunae.seo@...sung.com>,
	Heesub Shin <heesub@...il.com>,
	Heesub Shin <heesub.shin@...sung.com>
Subject: [PATCH] mm: zbud: fix condition check on allocation size

zbud_alloc() incorrectly verifies the size of allocation limit. It
should deny the allocation request greater than (PAGE_SIZE -
ZHDR_SIZE_ALIGNED - CHUNK_SIZE), not (PAGE_SIZE - ZHDR_SIZE_ALIGNED)
which has no remaining spaces for its buddy. There is no point in
spending the entire zbud page storing only a single page, since we don't
have any benefits.

Signed-off-by: Heesub Shin <heesub.shin@...sung.com>
---
 mm/zbud.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/zbud.c b/mm/zbud.c
index 9bb4710..ad1e781 100644
--- a/mm/zbud.c
+++ b/mm/zbud.c
@@ -257,7 +257,7 @@ int zbud_alloc(struct zbud_pool *pool, int size, gfp_t gfp,
 
 	if (size <= 0 || gfp & __GFP_HIGHMEM)
 		return -EINVAL;
-	if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED)
+	if (size > PAGE_SIZE - ZHDR_SIZE_ALIGNED - CHUNK_SIZE)
 		return -ENOSPC;
 	chunks = size_to_chunks(size);
 	spin_lock(&pool->lock);
-- 
1.8.3.2

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