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In-Reply-To: <20160909104637.2580-1-colin.king@canonical.com>
References: <20160909104637.2580-1-colin.king@canonical.com>
From: Alexey Klimov <klimov.linux@gmail.com>
Date: Fri, 9 Sep 2016 12:52:58 +0100
Message-ID: <CALW4P+K_ULv97bf3VVoFVwivcB7G2MxWx5P4S4hcxdnypsRpXA@mail.gmail.com>
Subject: Re: [PATCH] mm: mlock: check if vma is locked using & instead of && operator
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Sender: owner-linux-mm@kvack.org
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To: Colin King <colin.king@canonical.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, Vlastimil Babka <vbabka@suse.cz>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Michal Hocko <mhocko@suse.com>, Eric B Munson <emunson@akamai.com>, Simon Guo <wei.guo.simon@gmail.com>, Mel Gorman <mgorman@techsingularity.net>, linux-mm@kvack.org, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>

Hi Colin,

On Fri, Sep 9, 2016 at 11:46 AM, Colin King <colin.king@canonical.com> wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> The check to see if a vma is locked is using the operator && and
> should be using the bitwise operator & to see if the VM_LOCKED bit
> is set. Fix this to use & instead.
>
> Fixes: ae38c3be005ee ("mm: mlock: check against vma for actual mlock() size")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  mm/mlock.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/mlock.c b/mm/mlock.c
> index fafbb78..f5b1d07 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -643,7 +643,7 @@ static int count_mm_mlocked_page_nr(struct mm_struct *mm,
>         for (; vma ; vma = vma->vm_next) {
>                 if (start + len <=  vma->vm_start)
>                         break;
> -               if (vma->vm_flags && VM_LOCKED) {
> +               if (vma->vm_flags & VM_LOCKED) {
>                         if (start > vma->vm_start)
>                                 count -= (start - vma->vm_start);
>                         if (start + len < vma->vm_end) {
> --

I think it was already addressed in [1] by Simon Guo.

[1] http://www.spinics.net/lists/linux-mm/msg113228.html

-- 
Best regards,
Alexey

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