The patch titled
Subject: mm: percpu: fix incorrect size in pcpu_obj_full_size()
has been added to the -mm mm-unstable branch. Its filename is
mm-percpu-fix-incorrect-size-in-pcpu_obj_full_size.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-percpu-fix-incorrect-size-in-pcpu_obj_full_size.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yafang Shao <laoar.shao@xxxxxxxxx>
Subject: mm: percpu: fix incorrect size in pcpu_obj_full_size()
Date: Tue, 14 Feb 2023 15:35:49 +0000
The extra space which is used to store the obj_cgroup membership is only
valid when kmemcg is enabled. The kmemcg can be disabled via the kernel
parameter "cgroup.memory=nokmem" at boot time. This helper is also used
in non-memcg code, for example the tracepoint, so we should fix it.
It was found by code review when I was implementing bpf memory usage[1].
No real issue happens in production environment.
[1]. https://lwn.net/Articles/921991/
Link: https://lkml.kernel.org/r/20230214153549.12291-1-laoar.shao@xxxxxxxxx
Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Acked-by: Dennis Zhou <dennis@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Vasily Averin <vvs@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/percpu-internal.h~mm-percpu-fix-incorrect-size-in-pcpu_obj_full_size
+++ a/mm/percpu-internal.h
@@ -4,6 +4,7 @@
#include <linux/types.h>
#include <linux/percpu.h>
+#include <linux/memcontrol.h>
/*
* pcpu_block_md is the metadata block struct.
@@ -118,14 +119,15 @@ static inline int pcpu_chunk_map_bits(st
* @size: size of area to allocate in bytes
*
* For each accounted object there is an extra space which is used to store
- * obj_cgroup membership. Charge it too.
+ * obj_cgroup membership if kmemcg is not disabled. Charge it too.
*/
static inline size_t pcpu_obj_full_size(size_t size)
{
size_t extra_size = 0;
#ifdef CONFIG_MEMCG_KMEM
- extra_size += size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *);
+ if (!mem_cgroup_kmem_disabled())
+ extra_size += size / PCPU_MIN_ALLOC_SIZE * sizeof(struct obj_cgroup *);
#endif
return size * num_possible_cpus() + extra_size;
_
Patches currently in -mm which might be from laoar.shao@xxxxxxxxx are
mm-percpu-fix-incorrect-size-in-pcpu_obj_full_size.patch
