mm: delete stale comment about cachelines

[PATCH] mm: delete stale comment about cachelines

Posted by Brendan Jackman 6 days, 17 hours ago

These comments have been wrong since commit a211c6550efc ("mm:
page_alloc: defrag_mode kswapd/kcompactd watermarks") added
NR_FREE_PAGES_BLOCKS. Since nobody has complained about it in the last
year, it seems unlikely these comments were particularly useful anyway,
so delete them.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 include/linux/mmzone.h | 2 --
 1 file changed, 2 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 1331a7b93f33c..e308f5ac7950a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -214,7 +214,6 @@ enum numa_stat_item {
 #endif
 
 enum zone_stat_item {
-	/* First 128 byte cacheline (assuming 64 bit words) */
 	NR_FREE_PAGES,
 	NR_FREE_PAGES_BLOCKS,
 	NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
@@ -225,7 +224,6 @@ enum zone_stat_item {
 	NR_ZONE_UNEVICTABLE,
 	NR_ZONE_WRITE_PENDING,	/* Count of dirty, writeback and unstable pages */
 	NR_MLOCK,		/* mlock()ed pages found and moved off LRU */
-	/* Second 128 byte cacheline */
 #if IS_ENABLED(CONFIG_ZSMALLOC)
 	NR_ZSPAGES,		/* allocated in zsmalloc */
 #endif

---
base-commit: 4aedd91eef75addec6eb2702aa0d94625d01458d
change-id: 20260601-zone_stat_item-comment-45d660892420

Best regards,
-- 
Brendan Jackman <jackmanb@google.com>

Re: [PATCH] mm: delete stale comment about cachelines

Posted by Vlastimil Babka (SUSE) 6 days, 16 hours ago

On 6/1/26 13:40, Brendan Jackman wrote:
> These comments have been wrong since commit a211c6550efc ("mm:
> page_alloc: defrag_mode kswapd/kcompactd watermarks") added
> NR_FREE_PAGES_BLOCKS. Since nobody has complained about it in the last
> year, it seems unlikely these comments were particularly useful anyway,
> so delete them.
> 
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

> ---
>  include/linux/mmzone.h | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 1331a7b93f33c..e308f5ac7950a 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -214,7 +214,6 @@ enum numa_stat_item {
>  #endif
>  
>  enum zone_stat_item {
> -	/* First 128 byte cacheline (assuming 64 bit words) */
>  	NR_FREE_PAGES,
>  	NR_FREE_PAGES_BLOCKS,
>  	NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
> @@ -225,7 +224,6 @@ enum zone_stat_item {
>  	NR_ZONE_UNEVICTABLE,
>  	NR_ZONE_WRITE_PENDING,	/* Count of dirty, writeback and unstable pages */
>  	NR_MLOCK,		/* mlock()ed pages found and moved off LRU */
> -	/* Second 128 byte cacheline */
>  #if IS_ENABLED(CONFIG_ZSMALLOC)
>  	NR_ZSPAGES,		/* allocated in zsmalloc */
>  #endif
> 
> ---
> base-commit: 4aedd91eef75addec6eb2702aa0d94625d01458d
> change-id: 20260601-zone_stat_item-comment-45d660892420
> 
> Best regards,

Re: [PATCH] mm: delete stale comment about cachelines

Posted by Lorenzo Stoakes 6 days, 17 hours ago

On Mon, Jun 01, 2026 at 11:40:09AM +0000, Brendan Jackman wrote:
> These comments have been wrong since commit a211c6550efc ("mm:
> page_alloc: defrag_mode kswapd/kcompactd watermarks") added
> NR_FREE_PAGES_BLOCKS. Since nobody has complained about it in the last
> year, it seems unlikely these comments were particularly useful anyway,
> so delete them.
>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>

Ah, bitrot :)

LGTM so:

Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>

> ---
>  include/linux/mmzone.h | 2 --
>  1 file changed, 2 deletions(-)
>
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 1331a7b93f33c..e308f5ac7950a 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -214,7 +214,6 @@ enum numa_stat_item {
>  #endif
>
>  enum zone_stat_item {
> -	/* First 128 byte cacheline (assuming 64 bit words) */
>  	NR_FREE_PAGES,
>  	NR_FREE_PAGES_BLOCKS,
>  	NR_ZONE_LRU_BASE, /* Used only for compaction and reclaim retry */
> @@ -225,7 +224,6 @@ enum zone_stat_item {
>  	NR_ZONE_UNEVICTABLE,
>  	NR_ZONE_WRITE_PENDING,	/* Count of dirty, writeback and unstable pages */
>  	NR_MLOCK,		/* mlock()ed pages found and moved off LRU */
> -	/* Second 128 byte cacheline */
>  #if IS_ENABLED(CONFIG_ZSMALLOC)
>  	NR_ZSPAGES,		/* allocated in zsmalloc */
>  #endif
>
> ---
> base-commit: 4aedd91eef75addec6eb2702aa0d94625d01458d
> change-id: 20260601-zone_stat_item-comment-45d660892420
>
> Best regards,
> --
> Brendan Jackman <jackmanb@google.com>
>

Cheers, Lorenzo

Re: [PATCH] mm: delete stale comment about cachelines

Posted by David Hildenbrand (Arm) 6 days, 17 hours ago

On 6/1/26 13:40, Brendan Jackman wrote:
> These comments have been wrong since commit a211c6550efc ("mm:
> page_alloc: defrag_mode kswapd/kcompactd watermarks") added
> NR_FREE_PAGES_BLOCKS. Since nobody has complained about it in the last
> year, it seems unlikely these comments were particularly useful anyway,
> so delete them.

Agreed, let's just drop them.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David