2019-08-22 09:34:36

by Rasmus Villemoes

Subject: [PATCH] mm/init-mm.c: use CPU_BITS_NONE to initialize .cpu_bitmap

init_mm is sizeof(long) larger than it needs to be. Use the
CPU_BITS_NONE macro meant for this, which will initialize just the
indices 0...(BITS_TO_LONGS(NR_CPUS)-1) and hence make the array size
actually BITS_TO_LONGS(NR_CPUS).

Signed-off-by: Rasmus Villemoes <[email protected]>
---
mm/init-mm.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/init-mm.c b/mm/init-mm.c
index a787a319211e..fb1e15028ef0 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -35,6 +35,6 @@ struct mm_struct init_mm = {
.arg_lock = __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),
.mmlist = LIST_HEAD_INIT(init_mm.mmlist),
.user_ns = &init_user_ns,
- .cpu_bitmap = { [BITS_TO_LONGS(NR_CPUS)] = 0},
+ .cpu_bitmap = CPU_BITS_NONE,
INIT_MM_CONTEXT(init_mm)
};
--
2.20.1

2019-08-22 18:44:31

by Mike Rapoport

Subject: Re: [PATCH] mm/init-mm.c: use CPU_BITS_NONE to initialize .cpu_bitmap

Hi,

On Thu, Aug 22, 2019 at 09:52:07AM +0200, Rasmus Villemoes wrote:
> init_mm is sizeof(long) larger than it needs to be. Use the
> CPU_BITS_NONE macro meant for this, which will initialize just the
> indices 0...(BITS_TO_LONGS(NR_CPUS)-1) and hence make the array size
> actually BITS_TO_LONGS(NR_CPUS).

I've sent a similar patch [1] a week or so ago, it's in -mm tree.

[1] https://lore.kernel.org/linux-mm/[email protected]/

> Signed-off-by: Rasmus Villemoes <[email protected]>
> ---
> mm/init-mm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/init-mm.c b/mm/init-mm.c
> index a787a319211e..fb1e15028ef0 100644
> --- a/mm/init-mm.c
> +++ b/mm/init-mm.c
> @@ -35,6 +35,6 @@ struct mm_struct init_mm = {
> .arg_lock = __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),
> .mmlist = LIST_HEAD_INIT(init_mm.mmlist),
> .user_ns = &init_user_ns,
> - .cpu_bitmap = { [BITS_TO_LONGS(NR_CPUS)] = 0},
> + .cpu_bitmap = CPU_BITS_NONE,
> INIT_MM_CONTEXT(init_mm)
> };
> --
> 2.20.1
>
>

--
Sincerely yours,
Mike.