The patch titled
Subject: mm: fork: fix kernel_stack memcg stats for various stack implementations
has been added to the -mm tree. Its filename is
mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations.patch
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------------------------------------------------------
From: Roman Gushchin <guro@xxxxxx>
Subject: mm: fork: fix kernel_stack memcg stats for various stack implementations
Depending on CONFIG_VMAP_STACK and the THREAD_SIZE / PAGE_SIZE ratio the
space for task stacks can be allocated using __vmalloc_node_range(),
alloc_pages_node() and kmem_cache_alloc_node(). In the first and the
second cases page->mem_cgroup pointer is set, but in the third it's not:
memcg membership of a slab page should be determined using the
memcg_from_slab_page() function, which looks at
page->slab_cache->memcg_params.memcg . In this case, using
mod_memcg_page_state() (as in account_kernel_stack()) is incorrect:
page->mem_cgroup pointer is NULL even for pages charged to a non-root
memory cgroup.
It can lead to kernel_stack per-memcg counters permanently showing 0 on
some architectures (depending on the configuration).
In order to fix it, let's introduce a mod_memcg_obj_state() helper, which
takes a pointer to a kernel object as a first argument, uses
mem_cgroup_from_obj() to get a RCU-protected memcg pointer and calls
mod_memcg_state(). It allows to handle all possible configurations
(CONFIG_VMAP_STACK and various THREAD_SIZE/PAGE_SIZE values) without
spilling any memcg/kmem specifics into fork.c .
Note: this patch has been first posted as a part of the new slab
controller patchset. This is a slightly updated version: the fixes tag
has been added and the commit log was extended by the advice of Johannes
Weiner. Because it's a fix that makes sense by itself, I'm re-posting it
as a standalone patch.
Link: http://lkml.kernel.org/r/20200303233550.251375-1-guro@xxxxxx
Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Bharata B Rao <bharata@xxxxxxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 5 +++++
kernel/fork.c | 4 ++--
mm/memcontrol.c | 11 +++++++++++
3 files changed, 18 insertions(+), 2 deletions(-)
--- a/include/linux/memcontrol.h~mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations
+++ a/include/linux/memcontrol.h
@@ -695,6 +695,7 @@ static inline unsigned long lruvec_page_
void __mod_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
int val);
void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val);
+void mod_memcg_obj_state(void *p, int idx, int val);
static inline void mod_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx, int val)
@@ -1123,6 +1124,10 @@ static inline void __mod_lruvec_slab_sta
__mod_node_page_state(page_pgdat(page), idx, val);
}
+static inline void mod_memcg_obj_state(void *p, int idx, int val)
+{
+}
+
static inline
unsigned long mem_cgroup_soft_limit_reclaim(pg_data_t *pgdat, int order,
gfp_t gfp_mask,
--- a/kernel/fork.c~mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations
+++ a/kernel/fork.c
@@ -397,8 +397,8 @@ static void account_kernel_stack(struct
mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
THREAD_SIZE / 1024 * account);
- mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
- account * (THREAD_SIZE / 1024));
+ mod_memcg_obj_state(stack, MEMCG_KERNEL_STACK_KB,
+ account * (THREAD_SIZE / 1024));
}
}
--- a/mm/memcontrol.c~mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations
+++ a/mm/memcontrol.c
@@ -777,6 +777,17 @@ void __mod_lruvec_slab_state(void *p, en
rcu_read_unlock();
}
+void mod_memcg_obj_state(void *p, int idx, int val)
+{
+ struct mem_cgroup *memcg;
+
+ rcu_read_lock();
+ memcg = mem_cgroup_from_obj(p);
+ if (memcg)
+ mod_memcg_state(memcg, idx, val);
+ rcu_read_unlock();
+}
+
/**
* __count_memcg_events - account VM events in a cgroup
* @memcg: the memory cgroup
_
Patches currently in -mm which might be from guro@xxxxxx are
mm-fork-fix-kernel_stack-memcg-stats-for-various-stack-implementations.patch
mm-memcg-slab-introduce-mem_cgroup_from_obj.patch
mm-memcg-slab-introduce-mem_cgroup_from_obj-v2.patch
mm-kmem-cleanup-__memcg_kmem_charge_memcg-arguments.patch
mm-kmem-cleanup-memcg_kmem_uncharge_memcg-arguments.patch
mm-kmem-rename-memcg_kmem_uncharge-into-memcg_kmem_uncharge_page.patch
mm-kmem-switch-to-nr_pages-in-__memcg_kmem_charge_memcg.patch
mm-memcg-slab-cache-page-number-in-memcg_uncharge_slab.patch
mm-kmem-rename-__memcg_kmem_uncharge_memcg-to-__memcg_kmem_uncharge.patch
