linux-kernel - Re: [PATCH 6/8] mm/percpu.c: remove the lcm code since block size is fixed at page size

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Message-ID: <Y1bEtuGKvJffAAIU@fedora>
Date:   Mon, 24 Oct 2022 10:00:38 -0700
From:   Dennis Zhou <dennis@...nel.org>
To:     Baoquan He <bhe@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org
Subject: Re: [PATCH 6/8] mm/percpu.c: remove the lcm code since block size is
 fixed at page size

On Mon, Oct 24, 2022 at 04:14:33PM +0800, Baoquan He wrote:
> Since commit b239f7daf553 ("percpu: set PCPU_BITMAP_BLOCK_SIZE to
> PAGE_SIZE"), the PCPU_BITMAP_BLOCK_SIZE has been set to page size
> fixedly. So the lcm code in pcpu_alloc_first_chunk() doesn't make
> sense any more, clean it up.
> 
> Signed-off-by: Baoquan He <bhe@...hat.com>
> ---
>  mm/percpu.c | 12 ++----------
>  1 file changed, 2 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/percpu.c b/mm/percpu.c
> index 954abf916c7d..96191f7b61ba 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -72,7 +72,6 @@
>  #include <linux/cpumask.h>
>  #include <linux/memblock.h>
>  #include <linux/err.h>
> -#include <linux/lcm.h>
>  #include <linux/list.h>
>  #include <linux/log2.h>
>  #include <linux/mm.h>
> @@ -1347,7 +1346,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
>  							 int map_size)
>  {
>  	struct pcpu_chunk *chunk;
> -	unsigned long aligned_addr, lcm_align;
> +	unsigned long aligned_addr;
>  	int start_offset, offset_bits, region_size, region_bits;
>  	size_t alloc_size;
>  
> @@ -1355,14 +1354,7 @@ static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
>  	aligned_addr = tmp_addr & PAGE_MASK;
>  
>  	start_offset = tmp_addr - aligned_addr;
> -
> -	/*
> -	 * Align the end of the region with the LCM of PAGE_SIZE and
> -	 * PCPU_BITMAP_BLOCK_SIZE.  One of these constants is a multiple of
> -	 * the other.
> -	 */
> -	lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
> -	region_size = ALIGN(start_offset + map_size, lcm_align);
> +	region_size = ALIGN(start_offset + map_size, PAGE_SIZE);
>  
>  	/* allocate chunk */
>  	alloc_size = struct_size(chunk, populated,
> -- 
> 2.34.1
> 
> 

Acked-by: Dennis Zhou <dennis@...nel.org>

Thanks,
Dennis