diff options
author | Roman Gushchin <guro@fb.com> | 2020-03-28 19:17:25 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-03-29 09:47:05 -0700 |
commit | 8380ce479010f2f779587b462a9b4681934297c3 (patch) | |
tree | ec74864739f3bff28b926c2ab79477ccb6389152 | |
parent | 726b7bbeafd4e0219c37b74673d368b21ff3d039 (diff) | |
download | linux-8380ce479010f2f779587b462a9b4681934297c3.tar.bz2 |
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 is a special version of the patch created for stable
backports. It contains code from the following two patches:
- mm: memcg/slab: introduce mem_cgroup_from_obj()
- mm: fork: fix kernel_stack memcg stats for various stack implementations
[guro@fb.com: introduce mem_cgroup_from_obj()]
Link: http://lkml.kernel.org/r/20200324004221.GA36662@carbon.dhcp.thefacebook.com
Fixes: 4d96ba353075 ("mm: memcg/slab: stop setting page->mem_cgroup pointer for slab pages")
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Bharata B Rao <bharata@linux.ibm.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20200303233550.251375-1-guro@fb.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r-- | include/linux/memcontrol.h | 12 | ||||
-rw-r--r-- | kernel/fork.c | 4 | ||||
-rw-r--r-- | mm/memcontrol.c | 38 |
3 files changed, 52 insertions, 2 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index a7a0a1a5c8d5..e9ba01336d4e 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -695,6 +695,7 @@ static inline unsigned long lruvec_page_state_local(struct lruvec *lruvec, 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_state(void *p, enum node_stat_item idx, __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, @@ -1427,6 +1432,8 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg) return memcg ? memcg->kmemcg_id : -1; } +struct mem_cgroup *mem_cgroup_from_obj(void *p); + #else static inline int memcg_kmem_charge(struct page *page, gfp_t gfp, int order) @@ -1468,6 +1475,11 @@ static inline void memcg_put_cache_ids(void) { } +static inline struct mem_cgroup *mem_cgroup_from_obj(void *p) +{ + return NULL; +} + #endif /* CONFIG_MEMCG_KMEM */ #endif /* _LINUX_MEMCONTROL_H */ diff --git a/kernel/fork.c b/kernel/fork.c index 86425305cd4a..d90af13431c7 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -397,8 +397,8 @@ static void account_kernel_stack(struct task_struct *tsk, int account) 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)); } } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7a4bd8b9adc2..7ddf91c4295f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -777,6 +777,17 @@ void __mod_lruvec_slab_state(void *p, enum node_stat_item idx, int val) 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 @@ -2661,6 +2672,33 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg, } #ifdef CONFIG_MEMCG_KMEM +/* + * Returns a pointer to the memory cgroup to which the kernel object is charged. + * + * The caller must ensure the memcg lifetime, e.g. by taking rcu_read_lock(), + * cgroup_mutex, etc. + */ +struct mem_cgroup *mem_cgroup_from_obj(void *p) +{ + struct page *page; + + if (mem_cgroup_disabled()) + return NULL; + + page = virt_to_head_page(p); + + /* + * Slab pages don't have page->mem_cgroup set because corresponding + * kmem caches can be reparented during the lifetime. That's why + * memcg_from_slab_page() should be used instead. + */ + if (PageSlab(page)) + return memcg_from_slab_page(page); + + /* All other pages use page->mem_cgroup */ + return page->mem_cgroup; +} + static int memcg_alloc_cache_id(void) { int id, size; |