2022-10-24 08:24:36

by Baoquan He

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

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 <[email protected]>
---
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

2022-10-24 18:56:35

by Dennis Zhou

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 <[email protected]>
> ---
> 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 <[email protected]>

Thanks,
Dennis