2024-06-10 15:53:16

by Leesoo Ahn

Subject: [PATCH v2] mm/sparse: use MEMBLOCK_ALLOC_ACCESSIBLE enum instead of 0

Setting 'limit' variable to 0 might seem like it means "no limit". But
in the memblock API, 0 actually means the 'MEMBLOCK_ALLOC_ACCESSIBLE'
enum, which limits the physical address range end based on
'memblock.current_limit'. This could be confusing.

Use the enum instead of 0 to make it clear.

Signed-off-by: Leesoo Ahn <[email protected]>
---
v1 -> v2: do not rename 'limit' to 'limit_or_flag'
---
mm/sparse.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index de40b2c73406..cf93abc542ca 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -351,7 +351,7 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
again:
usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
if (!usage && limit) {
- limit = 0;
+ limit = MEMBLOCK_ALLOC_ACCESSIBLE;
goto again;
}
return usage;
--
2.34.1

2024-06-11 02:14:34

by Wei Yang

Subject: Re: [PATCH v2] mm/sparse: use MEMBLOCK_ALLOC_ACCESSIBLE enum instead of 0

On Tue, Jun 11, 2024 at 12:15:28AM +0900, Leesoo Ahn wrote:
>Setting 'limit' variable to 0 might seem like it means "no limit". But
>in the memblock API, 0 actually means the 'MEMBLOCK_ALLOC_ACCESSIBLE'
>enum, which limits the physical address range end based on
>'memblock.current_limit'. This could be confusing.
>
>Use the enum instead of 0 to make it clear.
>
>Signed-off-by: Leesoo Ahn <[email protected]>

Reviewed-by: Wei Yang <[email protected]>

>---
>v1 -> v2: do not rename 'limit' to 'limit_or_flag'
>---
> mm/sparse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/mm/sparse.c b/mm/sparse.c
>index de40b2c73406..cf93abc542ca 100644
>--- a/mm/sparse.c
>+++ b/mm/sparse.c
>@@ -351,7 +351,7 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
> again:
> usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
> if (!usage && limit) {
>- limit = 0;
>+ limit = MEMBLOCK_ALLOC_ACCESSIBLE;
> goto again;
> }
> return usage;
>--
>2.34.1
>

--
Wei Yang
Help you, Help me

2024-06-11 08:00:39

by Mike Rapoport

Subject: Re: [PATCH v2] mm/sparse: use MEMBLOCK_ALLOC_ACCESSIBLE enum instead of 0

On Tue, Jun 11, 2024 at 12:15:28AM +0900, Leesoo Ahn wrote:
> Setting 'limit' variable to 0 might seem like it means "no limit". But
> in the memblock API, 0 actually means the 'MEMBLOCK_ALLOC_ACCESSIBLE'
> enum, which limits the physical address range end based on
> 'memblock.current_limit'. This could be confusing.
>
> Use the enum instead of 0 to make it clear.
>
> Signed-off-by: Leesoo Ahn <[email protected]>

Acked-by: Mike Rapoport (IBM) <[email protected]>

> ---
> v1 -> v2: do not rename 'limit' to 'limit_or_flag'
> ---
> mm/sparse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index de40b2c73406..cf93abc542ca 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -351,7 +351,7 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
> again:
> usage = memblock_alloc_try_nid(size, SMP_CACHE_BYTES, goal, limit, nid);
> if (!usage && limit) {
> - limit = 0;
> + limit = MEMBLOCK_ALLOC_ACCESSIBLE;
> goto again;
> }
> return usage;
> --
> 2.34.1
>

--
Sincerely yours,
Mike.