diff mbox series

[v2,07/34] mm: clarify __GFP_ZEROTAGS comment

Message ID a2b2528f6d96fbc6a0c68f16e7212f80f3ef1505.1638825394.git.andreyknvl@google.com (mailing list archive)
State New
Headers show
Series kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS | expand

Commit Message

andrey.konovalov@linux.dev Dec. 6, 2021, 9:43 p.m. UTC 
From: Andrey Konovalov <andreyknvl@google.com>

__GFP_ZEROTAGS is intended as an optimization: if memory is zeroed during
allocation, it's possible to set memory tags at the same time with little
performance impact.

Clarify this intention of __GFP_ZEROTAGS in the comment.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 include/linux/gfp.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Andrey Konovalov Dec. 7, 2021, 5:33 p.m. UTC | #1 
On Mon, Dec 6, 2021 at 10:44 PM <andrey.konovalov@linux.dev> wrote:
>
> From: Andrey Konovalov <andreyknvl@google.com>
>
> __GFP_ZEROTAGS is intended as an optimization: if memory is zeroed during
> allocation, it's possible to set memory tags at the same time with little
> performance impact.
>
> Clarify this intention of __GFP_ZEROTAGS in the comment.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  include/linux/gfp.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index b976c4177299..dddd7597689f 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -232,8 +232,8 @@ struct vm_area_struct;
>   *
>   * %__GFP_ZERO returns a zeroed page on success.
>   *
> - * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
> - * __GFP_ZERO is set.
> + * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
> + * is being zeroed (either via __GFP_ZERO or via init_on_alloc).
>   *
>   * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned
>   * on deallocation. Typically used for userspace pages. Currently only has an
> --
> 2.25.1
>

Hi Peter,

Could you check whether I correctly understood the intention of
__GFP_ZEROTAGS and give your ack on this patch and the next one?

Thanks!
diff mbox series

Patch

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index b976c4177299..dddd7597689f 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -232,8 +232,8 @@  struct vm_area_struct;
  *
  * %__GFP_ZERO returns a zeroed page on success.
  *
- * %__GFP_ZEROTAGS returns a page with zeroed memory tags on success, if
- * __GFP_ZERO is set.
+ * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
+ * is being zeroed (either via __GFP_ZERO or via init_on_alloc).
  *
  * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned
  * on deallocation. Typically used for userspace pages. Currently only has an