The commit bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom
or alloc failures") added functionality to dump memcg protections on OOM
or allocation failures. It uses K() macro to dump the information and
passes bytes to the macro. However the macro take number of pages
instead of bytes. It is defined as:

 #define K(x) ((x) << (PAGE_SHIFT-10))

Let's fix this.

Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reported-by: Chris Mason <clm@fb.com>
Fixes: bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom or alloc failures")
---
 mm/memcontrol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e2e49f4ec9e0..6f000f0e76d2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5638,6 +5638,6 @@ void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg)
 		memcg = root_mem_cgroup;
 
 	pr_warn("Memory cgroup min protection %lukB -- low protection %lukB",
-		K(atomic_long_read(&memcg->memory.children_min_usage)*PAGE_SIZE),
-		K(atomic_long_read(&memcg->memory.children_low_usage)*PAGE_SIZE));
+		K(atomic_long_read(&memcg->memory.children_min_usage)),
+		K(atomic_long_read(&memcg->memory.children_low_usage)));
 }
-- 
2.47.3

On Tue 16-12-25 13:20:54, Shakeel Butt wrote:
> The commit bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom
> or alloc failures") added functionality to dump memcg protections on OOM
> or allocation failures. It uses K() macro to dump the information and
> passes bytes to the macro. However the macro take number of pages
> instead of bytes. It is defined as:
> 
>  #define K(x) ((x) << (PAGE_SHIFT-10))
> 
> Let's fix this.
> 
> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> Reported-by: Chris Mason <clm@fb.com>
> Fixes: bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom or alloc failures")

Acked-by: Michal Hocko <mhocko@suse.com>

Thanks!
> ---
>  mm/memcontrol.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e2e49f4ec9e0..6f000f0e76d2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5638,6 +5638,6 @@ void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg)
>  		memcg = root_mem_cgroup;
>  
>  	pr_warn("Memory cgroup min protection %lukB -- low protection %lukB",
> -		K(atomic_long_read(&memcg->memory.children_min_usage)*PAGE_SIZE),
> -		K(atomic_long_read(&memcg->memory.children_low_usage)*PAGE_SIZE));
> +		K(atomic_long_read(&memcg->memory.children_min_usage)),
> +		K(atomic_long_read(&memcg->memory.children_low_usage)));
>  }
> -- 
> 2.47.3
> 

-- 
Michal Hocko
SUSE Labs

On 12/16/25 22:20, Shakeel Butt wrote:
> The commit bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom
> or alloc failures") added functionality to dump memcg protections on OOM
> or allocation failures. It uses K() macro to dump the information and
> passes bytes to the macro. However the macro take number of pages
> instead of bytes. It is defined as:
> 
>  #define K(x) ((x) << (PAGE_SHIFT-10))
> 
> Let's fix this.
> 
> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> Reported-by: Chris Mason <clm@fb.com>
> Fixes: bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom or alloc failures")

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/memcontrol.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e2e49f4ec9e0..6f000f0e76d2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -5638,6 +5638,6 @@ void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg)
>  		memcg = root_mem_cgroup;
>  
>  	pr_warn("Memory cgroup min protection %lukB -- low protection %lukB",
> -		K(atomic_long_read(&memcg->memory.children_min_usage)*PAGE_SIZE),
> -		K(atomic_long_read(&memcg->memory.children_low_usage)*PAGE_SIZE));
> +		K(atomic_long_read(&memcg->memory.children_min_usage)),
> +		K(atomic_long_read(&memcg->memory.children_low_usage)));
>  }

> On Dec 17, 2025, at 05:20, Shakeel Butt <shakeel.butt@linux.dev> wrote:
> 
> The commit bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom
> or alloc failures") added functionality to dump memcg protections on OOM
> or allocation failures. It uses K() macro to dump the information and
> passes bytes to the macro. However the macro take number of pages
> instead of bytes. It is defined as:
> 
> #define K(x) ((x) << (PAGE_SHIFT-10))
> 
> Let's fix this.
> 
> Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> Reported-by: Chris Mason <clm@fb.com>
> Fixes: bc8e51c05ad5 ("mm: memcg: dump memcg protection info on oom or alloc failures")

Reviewed-by: Muchun Song <muchun.song@linux.dev>

Thanks.