linux-kernel - [PATCH] mm: memcg: fix unit conversion for K() macro in OOM log

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Message-ID: <20251216212054.484079-1-shakeel.butt@linux.dev>
Date: Tue, 16 Dec 2025 13:20:54 -0800
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...nel.org>,
	Roman Gushchin <roman.gushchin@...ux.dev>,
	Muchun Song <muchun.song@...ux.dev>,
	Vlastimil Babka <vbabka@...e.cz>,
	Meta kernel team <kernel-team@...a.com>,
	cgroups@...r.kernel.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Chris Mason <clm@...com>
Subject: [PATCH] mm: memcg: fix unit conversion for K() macro in OOM log

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@...ux.dev>
Reported-by: Chris Mason <clm@...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