2022-10-24 08:21:16

by Baoquan He

Subject: [PATCH 3/8] mm/percpu: Update the code comment when creating new chunk

The lock pcpu_alloc_mutex taking code has been moved to the beginning of
pcpu_allo() if it's non atomic allocation. So the code comment above
above pcpu_create_chunk() callsite need be updated.

Signed-off-by: Baoquan He <[email protected]>
---
mm/percpu.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index a3fde4ac03a4..a8121302a79c 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1817,16 +1817,12 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,

spin_unlock_irqrestore(&pcpu_lock, flags);

- /*
- * No space left. Create a new chunk. We don't want multiple
- * tasks to create chunks simultaneously. Serialize and create iff
- * there's still no empty chunk after grabbing the mutex.
- */
if (is_atomic) {
err = "atomic alloc failed, no space left";
goto fail;
}

+ /* No space left. Create a new chunk. */
if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
chunk = pcpu_create_chunk(pcpu_gfp);
if (!chunk) {
--
2.34.1

2022-10-24 18:31:16

by Dennis Zhou

Subject: Re: [PATCH 3/8] mm/percpu: Update the code comment when creating new chunk

On Mon, Oct 24, 2022 at 04:14:30PM +0800, Baoquan He wrote:
> The lock pcpu_alloc_mutex taking code has been moved to the beginning of
> pcpu_allo() if it's non atomic allocation. So the code comment above

Typo here ^ pcpu_alloc().

> above pcpu_create_chunk() callsite need be updated.
>
> Signed-off-by: Baoquan He <[email protected]>
> ---
> mm/percpu.c | 6 +-----
> 1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/mm/percpu.c b/mm/percpu.c
> index a3fde4ac03a4..a8121302a79c 100644
> --- a/mm/percpu.c
> +++ b/mm/percpu.c
> @@ -1817,16 +1817,12 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
>
> spin_unlock_irqrestore(&pcpu_lock, flags);
>
> - /*
> - * No space left. Create a new chunk. We don't want multiple
> - * tasks to create chunks simultaneously. Serialize and create iff
> - * there's still no empty chunk after grabbing the mutex.
> - */
> if (is_atomic) {
> err = "atomic alloc failed, no space left";
> goto fail;
> }
>
> + /* No space left. Create a new chunk. */
> if (list_empty(&pcpu_chunk_lists[pcpu_free_slot])) {
> chunk = pcpu_create_chunk(pcpu_gfp);
> if (!chunk) {
> --
> 2.34.1
>
>

Acked-by: Dennis Zhou <[email protected]>

Thanks,
Dennis