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[PATCH] mm: mlock: check if vma is locked using & instead of && operator

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  [PATCH] mm: mlock: check if vma is locked using & instead of && operator Colin King <colin.king@canonical.com> - 2016-09-09 12:50 +0200
    Re: [PATCH] mm: mlock: check if vma is locked using & instead of && operator Alexey Klimov <klimov.linux@gmail.com> - 2016-09-09 14:00 +0200

#1479863 — [PATCH] mm: mlock: check if vma is locked using & instead of && operator

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) {
-- 
2.9.3

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#1479922

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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