linux-kernel - [PATCH 1/3] fs/userfaultfd.c: remove a redundant check on end

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Message-Id: <20190912213110.3691-1-richardw.yang@linux.intel.com>
Date:   Fri, 13 Sep 2019 05:31:08 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     viro@...iv.linux.org.uk
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH 1/3] fs/userfaultfd.c: remove a redundant check on end

For the ending vma, there is a check to make sure the end is huge page
aligned.

The *if* check makes sure vm_start < end <= vm_end. While the first half
is not necessary, because the *for* clause makes sure vm_start < end.

This patch just removes it.

Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
---
 fs/userfaultfd.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index 653d8f7c453c..9ce09ac619a2 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 		 * If this vma contains ending address, and huge pages
 		 * check alignment.
 		 */
-		if (is_vm_hugetlb_page(cur) && end <= cur->vm_end &&
-		    end > cur->vm_start) {
+		if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
 			unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
 
 			ret = -EINVAL;
-- 
2.17.1