linux-kernel - [PATCH mm] limit the mm->map_count not greater than sysctl_max_map

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Date:	Wed, 18 Apr 2012 05:27:19 -0400
From:	Li Zhong <zhong@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-mm@...ck.org, akpm@...ux-foundation.org
Subject: [PATCH mm] limit the mm->map_count not greater than
 sysctl_max_map_count

When reading the mmap codes, I found the checking of mm->map_count
against sysctl_max_map_count is not consistent. At some places, ">" is
used; at some other places, ">=" is used.

This patch changes ">" to ">=", so they are consistent, and makes sure
the value is not greater (one more) than sysctl_max_map_count.

Signed-off-by: Li Zhong <zhong@...ux.vnet.ibm.com>
---
 mm/mmap.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index a7bf6a3..85f4816 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -987,7 +987,7 @@ unsigned long do_mmap_pgoff(struct file *file,
unsigned long addr,
                return -EOVERFLOW;
 
 	/* Too many mappings? */
-	if (mm->map_count > sysctl_max_map_count)
+	if (mm->map_count >= sysctl_max_map_count)
 		return -ENOMEM;
 
 	/* Obtain the address to map to. we verify (or select) it and ensure
@@ -2193,7 +2193,7 @@ unsigned long do_brk(unsigned long addr, unsigned
long len)
 	if (!may_expand_vm(mm, len >> PAGE_SHIFT))
 		return -ENOMEM;
 
-	if (mm->map_count > sysctl_max_map_count)
+	if (mm->map_count >= sysctl_max_map_count)
 		return -ENOMEM;
 
 	if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT))
-- 
1.7.6.5



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