linux-kernel - Re: [PATCH] fs/userfaultfd.c: simplify the calculation of new

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Date:   Thu, 12 Sep 2019 10:54:24 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     Wei Yang <richardw.yang@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk,
        linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH] fs/userfaultfd.c: simplify the calculation of new_flags

Ping~

On Tue, Aug 06, 2019 at 01:38:59PM +0800, Wei Yang wrote:
>Finally new_flags equals old vm_flags *OR* vm_flags.
>
>It is not necessary to mask them first.
>
>Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
>---
> fs/userfaultfd.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
>index ccbdbd62f0d8..653d8f7c453c 100644
>--- a/fs/userfaultfd.c
>+++ b/fs/userfaultfd.c
>@@ -1457,7 +1457,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
> 			start = vma->vm_start;
> 		vma_end = min(end, vma->vm_end);
> 
>-		new_flags = (vma->vm_flags & ~vm_flags) | vm_flags;
>+		new_flags = vma->vm_flags | vm_flags;
> 		prev = vma_merge(mm, prev, start, vma_end, new_flags,
> 				 vma->anon_vma, vma->vm_file, vma->vm_pgoff,
> 				 vma_policy(vma),
>-- 
>2.17.1

-- 
Wei Yang
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