linux-kernel - [PATCH v3 1/3] mm/mempolicy: remove redundant check in get

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Date:   Fri, 17 Nov 2017 09:37:02 +0800
From:   Yisheng Xie <xieyisheng1@...wei.com>
To:     <akpm@...ux-foundation.org>, <vbabka@...e.cz>, <mhocko@...e.com>,
        <mingo@...nel.org>, <rientjes@...gle.com>,
        <n-horiguchi@...jp.nec.com>, <salls@...ucsb.edu>,
        <ak@...ux.intel.com>, <cl@...ux.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        <linux-api@...r.kernel.org>, <tanxiaojun@...wei.com>
Subject: [PATCH v3 1/3] mm/mempolicy: remove redundant check in get_nodes

We have already checked whether maxnode is a page worth of bits, by:
    maxnode > PAGE_SIZE*BITS_PER_BYTE

So no need to check it once more.

Acked-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Yisheng Xie <xieyisheng1@...wei.com>
---
 mm/mempolicy.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 4ce44d3..6e867a8 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1282,8 +1282,6 @@ static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
 	/* When the user specified more nodes than supported just check
 	   if the non supported part is all zero. */
 	if (nlongs > BITS_TO_LONGS(MAX_NUMNODES)) {
-		if (nlongs > PAGE_SIZE/sizeof(long))
-			return -EINVAL;
 		for (k = BITS_TO_LONGS(MAX_NUMNODES); k < nlongs; k++) {
 			unsigned long t;
 			if (get_user(t, nmask + k))
-- 
1.8.3.1