[PATCH v4 0/2] Directed kmem charging

[PATCH v4 0/2] Directed kmem charging

[Shakeel Butt]

This patchset introduces memcg variant memory allocation functions. The
caller can explicitly pass the memcg to charge for kmem allocations.
Currently the kernel, for __GFP_ACCOUNT memory allocation requests,
extract the memcg of the current task to charge for the kmem allocation.
This patch series introduces kmem allocation functions where the caller
can pass the pointer to the remote memcg. The remote memcg will be
charged for the allocation instead of the memcg of the caller. However
the caller must have a reference to the remote memcg.

Fixed the build for SLOB in v2, added the target_memcg in task_struct in
v3 and in v4, added node variant for kmem allocation functions and
rebased fsnotify patch over Jan's patches.


Shakeel Butt (2):
  mm: memcg: remote memcg charging for kmem allocations
  fs: fsnotify: account fsnotify metadata to kmemcg

 fs/notify/dnotify/dnotify.c          |  5 ++-
 fs/notify/fanotify/fanotify.c        |  6 ++-
 fs/notify/fanotify/fanotify_user.c   |  5 ++-
 fs/notify/group.c                    |  4 ++
 fs/notify/inotify/inotify_fsnotify.c |  2 +-
 fs/notify/inotify/inotify_user.c     |  5 ++-
 include/linux/fsnotify_backend.h     | 12 ++++--
 include/linux/memcontrol.h           |  7 ++++
 include/linux/sched.h                |  3 ++
 include/linux/sched/mm.h             | 23 +++++++++++
 include/linux/slab.h                 | 59 ++++++++++++++++++++++++++++
 kernel/fork.c                        |  3 ++
 mm/memcontrol.c                      | 25 +++++++++---
 13 files changed, 143 insertions(+), 16 deletions(-)

-- 
2.16.2.395.g2e18187dfd-goog

[PATCH v4 1/2] mm: memcg: remote memcg charging for kmem allocations

[Shakeel Butt]

Introducing the memcg variant for kmalloc[_node] and
kmem_cache_alloc[_node]. For kmem_cache_alloc, the kernel switches the
root kmem cache with the memcg specific kmem cache for __GFP_ACCOUNT
allocations to charge those allocations to the memcg. However, the
memcg to charge is extracted from the current task_struct. This patch
introduces the variant of kmem cache allocation functions where the
memcg can be provided explicitly by the caller instead of deducing the
memcg from the current task.

The kmalloc allocations are underlying served using the kmem caches
unless the size of the allocation request is larger than
KMALLOC_MAX_CACHE_SIZE, in which case, the kmem caches are bypassed and
the request is routed directly to page allocator. So, for __GFP_ACCOUNT
kmalloc allocations, the memcg of current task is charged. This patch
introduces memcg variant of kmalloc functions to allow callers to
provide memcg for charging.

These functions are useful for use-cases where the allocations should be
charged to the memcg different from the memcg of the caller. One such
concrete use-case is the allocations for fsnotify event objects where
the objects should be charged to the listener instead of the producer.

One requirement to call these functions is that the caller must have the
reference to the memcg. Using kmalloc_memcg and kmem_cache_alloc_memcg
implicitly assumes that the caller is requesting a __GFP_ACCOUNT
allocation.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
---
Changelog since v3:
- Added node variant of directed kmem allocation functions.

Changelog since v2:
- Merge the kmalloc_memcg patch into this patch.
- Instead of plumbing memcg throughout, use field in task_struct to pass
  the target_memcg.

Changelog since v1:
- Fixed build for SLOB

 include/linux/sched.h    |  3 ++
 include/linux/sched/mm.h | 23 ++++++++++++++++
 include/linux/slab.h     | 59 ++++++++++++++++++++++++++++++++++++++++
 kernel/fork.c            |  3 ++
 mm/memcontrol.c          | 23 +++++++++++++---
 5 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b161ef8a902e..847cb94fead7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1069,6 +1069,9 @@ struct task_struct {
 
 	/* Number of pages to reclaim on returning to userland: */
 	unsigned int			memcg_nr_pages_over_high;
+
+	/* Used by memcontrol for targeted memcg charge: */
+	struct mem_cgroup		*target_memcg;
 #endif
 
 #ifdef CONFIG_UPROBES
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 2c570cd934af..c9255cbd94d3 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -206,6 +206,29 @@ static inline void memalloc_noreclaim_restore(unsigned int flags)
 	current->flags = (current->flags & ~PF_MEMALLOC) | flags;
 }
 
+#ifdef CONFIG_MEMCG
+static inline struct mem_cgroup *memalloc_memcg_save(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *old_memcg = current->target_memcg;
+
+	current->target_memcg = memcg;
+	return old_memcg;
+}
+
+static inline void memalloc_memcg_restore(struct mem_cgroup *memcg)
+{
+	current->target_memcg = memcg;
+}
+#else
+static inline struct mem_cgroup *memalloc_memcg_save(struct mem_cgroup *memcg)
+{
+	return NULL;
+}
+
+static inline void memalloc_memcg_restore(struct mem_cgroup *memcg)
+{
+}
+#endif /* CONFIG_MEMCG */
+
 #ifdef CONFIG_MEMBARRIER
 enum {
 	MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY		= (1U << 0),
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 508aa9b596b3..70b6f540588f 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -15,6 +15,7 @@
 #include <linux/gfp.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
+#include <linux/sched/mm.h>
 
 
 /*
@@ -373,6 +374,21 @@ static __always_inline void kfree_bulk(size_t size, void **p)
 	kmem_cache_free_bulk(NULL, size, p);
 }
 
+/*
+ * Calling kmem_cache_alloc_memcg implicitly assumes that the caller
+ * wants a __GFP_ACCOUNT allocation.
+ */
+static __always_inline void *kmem_cache_alloc_memcg(struct kmem_cache *cachep,
+						    gfp_t flags,
+						    struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *old_memcg = memalloc_memcg_save(memcg);
+	void *ptr = kmem_cache_alloc(cachep, flags | __GFP_ACCOUNT);
+
+	memalloc_memcg_restore(old_memcg);
+	return ptr;
+}
+
 #ifdef CONFIG_NUMA
 void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_kmalloc_alignment __malloc;
 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node) __assume_slab_alignment __malloc;
@@ -388,6 +404,21 @@ static __always_inline void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t f
 }
 #endif
 
+/*
+ * Calling kmem_cache_alloc_node_memcg implicitly assumes that the caller
+ * wants a __GFP_ACCOUNT allocation.
+ */
+static __always_inline void *
+kmem_cache_alloc_node_memcg(struct kmem_cache *cachep, gfp_t flags, int node,
+			    struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *old_memcg = memalloc_memcg_save(memcg);
+	void *ptr = kmem_cache_alloc_node(cachep, flags | __GFP_ACCOUNT, node);
+
+	memalloc_memcg_restore(old_memcg);
+	return ptr;
+}
+
 #ifdef CONFIG_TRACING
 extern void *kmem_cache_alloc_trace(struct kmem_cache *, gfp_t, size_t) __assume_slab_alignment __malloc;
 
@@ -516,6 +547,20 @@ static __always_inline void *kmalloc(size_t size, gfp_t flags)
 	return __kmalloc(size, flags);
 }
 
+/*
+ * Calling kmalloc_memcg implicitly assumes that the caller wants a
+ * __GFP_ACCOUNT allocation.
+ */
+static __always_inline void *kmalloc_memcg(size_t size, gfp_t flags,
+					   struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *old_memcg = memalloc_memcg_save(memcg);
+	void *ptr = kmalloc(size, flags | __GFP_ACCOUNT);
+
+	memalloc_memcg_restore(old_memcg);
+	return ptr;
+}
+
 /*
  * Determine size used for the nth kmalloc cache.
  * return size or 0 if a kmalloc cache for that
@@ -553,6 +598,20 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
 	return __kmalloc_node(size, flags, node);
 }
 
+/*
+ * Calling kmalloc_node_memcg implicitly assumes that the caller wants a
+ * __GFP_ACCOUNT allocation.
+ */
+static __always_inline void *
+kmalloc_node_memcg(size_t size, gfp_t flags, int node, struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *old_memcg = memalloc_memcg_save(memcg);
+	void *ptr = kmalloc_node(size, flags | __GFP_ACCOUNT, node);
+
+	memalloc_memcg_restore(old_memcg);
+	return ptr;
+}
+
 struct memcg_cache_array {
 	struct rcu_head rcu;
 	struct kmem_cache *entries[0];
diff --git a/kernel/fork.c b/kernel/fork.c
index 833941a06e41..a32e1c4311b2 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -833,6 +833,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 	tsk->fail_nth = 0;
 #endif
 
+#ifdef CONFIG_MEMCG
+	tsk->target_memcg = NULL;
+#endif
 	return tsk;
 
 free_stack:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index afdb35cf4d0e..5a2acfbc4962 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -701,6 +701,15 @@ static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
 	return memcg;
 }
 
+static struct mem_cgroup *get_mem_cgroup(struct mem_cgroup *memcg)
+{
+	rcu_read_lock();
+	if (!css_tryget_online(&memcg->css))
+		memcg = NULL;
+	rcu_read_unlock();
+	return memcg;
+}
+
 /**
  * mem_cgroup_iter - iterate over memory cgroup hierarchy
  * @root: hierarchy root
@@ -2248,7 +2257,7 @@ static inline bool memcg_kmem_bypass(void)
  */
 struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
 {
-	struct mem_cgroup *memcg;
+	struct mem_cgroup *memcg = NULL;
 	struct kmem_cache *memcg_cachep;
 	int kmemcg_id;
 
@@ -2260,7 +2269,10 @@ struct kmem_cache *memcg_kmem_get_cache(struct kmem_cache *cachep)
 	if (current->memcg_kmem_skip_account)
 		return cachep;
 
-	memcg = get_mem_cgroup_from_mm(current->mm);
+	if (current->target_memcg)
+		memcg = get_mem_cgroup(current->target_memcg);
+	if (!memcg)
+		memcg = get_mem_cgroup_from_mm(current->mm);
 	kmemcg_id = READ_ONCE(memcg->kmemcg_id);
 	if (kmemcg_id < 0)
 		goto out;
@@ -2338,13 +2350,16 @@ int memcg_kmem_charge_memcg(struct page *page, gfp_t gfp, int order,
  */
 int memcg_kmem_charge(struct page *page, gfp_t gfp, int order)
 {
-	struct mem_cgroup *memcg;
+	struct mem_cgroup *memcg = NULL;
 	int ret = 0;
 
 	if (memcg_kmem_bypass())
 		return 0;
 
-	memcg = get_mem_cgroup_from_mm(current->mm);
+	if (current->target_memcg)
+		memcg = get_mem_cgroup(current->target_memcg);
+	if (!memcg)
+		memcg = get_mem_cgroup_from_mm(current->mm);
 	if (!mem_cgroup_is_root(memcg)) {
 		ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
 		if (!ret)
-- 
2.16.2.395.g2e18187dfd-goog

[PATCH v4 2/2] fs: fsnotify: account fsnotify metadata to kmemcg

[Shakeel Butt]

A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener. This can cause
system level memory pressure or OOMs. So, it's better to account the
fsnotify kmem caches to the memcg of the listener.

There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener. So, SLAB_ACCOUNT is enough for these caches.

The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.

The allocations from the event caches happen in the context of the event
producer. For such caches we will need to remote charge the allocations
to the listener's memcg. Thus we save the memcg reference in the
fsnotify_group structure of the listener.

This patch has also moved the members of fsnotify_group to keep the
size same, at least for 64 bit build, even with additional member by
filling the holes.

Signed-off-by: Shakeel Butt <shakeelb@google.com>
---
Changelog since v3:
- Rebased over Jan's patches.
- Some cleanup based on Amir's comments.

Changelog since v2:
- None

Changelog since v1:
- no more charging fsnotify_mark_connector objects
- Fixed the build for SLOB

 fs/notify/dnotify/dnotify.c          |  5 +++--
 fs/notify/fanotify/fanotify.c        |  6 ++++--
 fs/notify/fanotify/fanotify_user.c   |  5 ++++-
 fs/notify/group.c                    |  4 ++++
 fs/notify/inotify/inotify_fsnotify.c |  2 +-
 fs/notify/inotify/inotify_user.c     |  5 ++++-
 include/linux/fsnotify_backend.h     | 12 ++++++++----
 include/linux/memcontrol.h           |  7 +++++++
 mm/memcontrol.c                      |  2 +-
 9 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 63a1ca4b9dee..eb5c41284649 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -384,8 +384,9 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
 
 static int __init dnotify_init(void)
 {
-	dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
-	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
+	dnotify_struct_cache = KMEM_CACHE(dnotify_struct,
+					  SLAB_PANIC|SLAB_ACCOUNT);
+	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC|SLAB_ACCOUNT);
 
 	dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
 	if (IS_ERR(dnotify_group))
diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index d51e1bb781cf..cb6670bed289 100644
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -157,14 +157,16 @@ struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
 	if (fanotify_is_perm_event(mask)) {
 		struct fanotify_perm_event_info *pevent;
 
-		pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
+		pevent = kmem_cache_alloc_memcg(fanotify_perm_event_cachep, gfp,
+						group->memcg);
 		if (!pevent)
 			return NULL;
 		event = &pevent->fae;
 		pevent->response = 0;
 		goto init;
 	}
-	event = kmem_cache_alloc(fanotify_event_cachep, gfp);
+	event = kmem_cache_alloc_memcg(fanotify_event_cachep, gfp,
+				       group->memcg);
 	if (!event)
 		return NULL;
 init: __maybe_unused
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 72e367822efb..6015bbaaa319 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -16,6 +16,7 @@
 #include <linux/uaccess.h>
 #include <linux/compat.h>
 #include <linux/sched/signal.h>
+#include <linux/memcontrol.h>
 
 #include <asm/ioctls.h>
 
@@ -756,6 +757,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
 
 	group->fanotify_data.user = user;
 	atomic_inc(&user->fanotify_listeners);
+	group->memcg = get_mem_cgroup_from_mm(current->mm);
 
 	oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL);
 	if (unlikely(!oevent)) {
@@ -951,7 +953,8 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
  */
 static int __init fanotify_user_setup(void)
 {
-	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
+	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
+					 SLAB_PANIC|SLAB_ACCOUNT);
 	fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
 	if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
 		fanotify_perm_event_cachep =
diff --git a/fs/notify/group.c b/fs/notify/group.c
index b7a4b6a69efa..df14a66ce067 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -22,6 +22,7 @@
 #include <linux/srcu.h>
 #include <linux/rculist.h>
 #include <linux/wait.h>
+#include <linux/memcontrol.h>
 
 #include <linux/fsnotify_backend.h>
 #include "fsnotify.h"
@@ -36,6 +37,9 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *group)
 	if (group->ops->free_group_priv)
 		group->ops->free_group_priv(group);
 
+	if (group->memcg)
+		css_put(&group->memcg->css);
+
 	kfree(group);
 }
 
diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
index 40dedb37a1f3..b184bff93d02 100644
--- a/fs/notify/inotify/inotify_fsnotify.c
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -98,7 +98,7 @@ int inotify_handle_event(struct fsnotify_group *group,
 	i_mark = container_of(inode_mark, struct inotify_inode_mark,
 			      fsn_mark);
 
-	event = kmalloc(alloc_len, GFP_KERNEL);
+	event = kmalloc_memcg(alloc_len, GFP_KERNEL, group->memcg);
 	if (unlikely(!event)) {
 		/*
 		 * Treat lost event due to ENOMEM the same way as queue
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 8f17719842ec..d9e4b243c973 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -38,6 +38,7 @@
 #include <linux/uaccess.h>
 #include <linux/poll.h>
 #include <linux/wait.h>
+#include <linux/memcontrol.h>
 
 #include "inotify.h"
 #include "../fdinfo.h"
@@ -632,6 +633,7 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
 	oevent->name_len = 0;
 
 	group->max_events = max_events;
+	group->memcg = get_mem_cgroup_from_mm(current->mm);
 
 	spin_lock_init(&group->inotify_data.idr_lock);
 	idr_init(&group->inotify_data.idr);
@@ -799,7 +801,8 @@ static int __init inotify_user_setup(void)
 
 	BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
 
-	inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
+	inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark,
+					       SLAB_PANIC|SLAB_ACCOUNT);
 
 	inotify_max_queued_events = 16384;
 	init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 9f1edb92c97e..81bd86dfa2cd 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -84,6 +84,8 @@ struct fsnotify_event_private_data;
 struct fsnotify_fname;
 struct fsnotify_iter_info;
 
+struct mem_cgroup;
+
 /*
  * Each group much define these ops.  The fsnotify infrastructure will call
  * these operations for each relevant group.
@@ -129,6 +131,8 @@ struct fsnotify_event {
  * everything will be cleaned up.
  */
 struct fsnotify_group {
+	const struct fsnotify_ops *ops;	/* how this group handles things */
+
 	/*
 	 * How the refcnt is used is up to each group.  When the refcnt hits 0
 	 * fsnotify will clean up all of the resources associated with this group.
@@ -139,8 +143,6 @@ struct fsnotify_group {
 	 */
 	refcount_t refcnt;		/* things with interest in this group */
 
-	const struct fsnotify_ops *ops;	/* how this group handles things */
-
 	/* needed to send notification to userspace */
 	spinlock_t notification_lock;		/* protect the notification_list */
 	struct list_head notification_list;	/* list of event_holder this group needs to send to userspace */
@@ -162,6 +164,8 @@ struct fsnotify_group {
 	atomic_t num_marks;		/* 1 for each mark and 1 for not being
 					 * past the point of no return when freeing
 					 * a group */
+	atomic_t user_waits;		/* Number of tasks waiting for user
+					 * response */
 	struct list_head marks_list;	/* all inode marks for this group */
 
 	struct fasync_struct *fsn_fa;    /* async notification */
@@ -169,8 +173,8 @@ struct fsnotify_group {
 	struct fsnotify_event *overflow_event;	/* Event we queue when the
 						 * notification list is too
 						 * full */
-	atomic_t user_waits;		/* Number of tasks waiting for user
-					 * response */
+
+	struct mem_cgroup *memcg;	/* memcg to charge allocations */
 
 	/* groups can define private fields here or use the void *private */
 	union {
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index c79cdf9f8138..4525b4404a9e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -352,6 +352,8 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
 	return css ? container_of(css, struct mem_cgroup, css) : NULL;
 }
 
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
+
 static inline void mem_cgroup_put(struct mem_cgroup *memcg)
 {
 	css_put(&memcg->css);
@@ -809,6 +811,11 @@ static inline bool task_in_mem_cgroup(struct task_struct *task,
 	return true;
 }
 
+static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+{
+	return NULL;
+}
+
 static inline void mem_cgroup_put(struct mem_cgroup *memcg)
 {
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5a2acfbc4962..3801ac1fcfbc 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -678,7 +678,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
 }
 EXPORT_SYMBOL(mem_cgroup_from_task);
 
-static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
 {
 	struct mem_cgroup *memcg = NULL;
 
-- 
2.16.2.395.g2e18187dfd-goog

Re: [PATCH v4 2/2] fs: fsnotify: account fsnotify metadata to kmemcg

[Jan Kara]

On Mon 05-03-18 10:29:51, Shakeel Butt wrote:
> A lot of memory can be consumed by the events generated for the huge or
> unlimited queues if there is either no or slow listener. This can cause
> system level memory pressure or OOMs. So, it's better to account the
> fsnotify kmem caches to the memcg of the listener.
> 
> There are seven fsnotify kmem caches and among them allocations from
> dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
> inotify_inode_mark_cachep happens in the context of syscall from the
> listener. So, SLAB_ACCOUNT is enough for these caches.
> 
> The objects from fsnotify_mark_connector_cachep are not accounted as
> they are small compared to the notification mark or events and it is
> unclear whom to account connector to since it is shared by all events
> attached to the inode.
> 
> The allocations from the event caches happen in the context of the event
> producer. For such caches we will need to remote charge the allocations
> to the listener's memcg. Thus we save the memcg reference in the
> fsnotify_group structure of the listener.
> 
> This patch has also moved the members of fsnotify_group to keep the
> size same, at least for 64 bit build, even with additional member by
> filling the holes.
> 
> Signed-off-by: Shakeel Butt <shakeelb@google.com>

The patch looks OK to me from fsnotify POV. So feel free to add:

Acked-by: Jan Kara <jack@suse.cz>

								Honza

> ---
> Changelog since v3:
> - Rebased over Jan's patches.
> - Some cleanup based on Amir's comments.
> 
> Changelog since v2:
> - None
> 
> Changelog since v1:
> - no more charging fsnotify_mark_connector objects
> - Fixed the build for SLOB
> 
>  fs/notify/dnotify/dnotify.c          |  5 +++--
>  fs/notify/fanotify/fanotify.c        |  6 ++++--
>  fs/notify/fanotify/fanotify_user.c   |  5 ++++-
>  fs/notify/group.c                    |  4 ++++
>  fs/notify/inotify/inotify_fsnotify.c |  2 +-
>  fs/notify/inotify/inotify_user.c     |  5 ++++-
>  include/linux/fsnotify_backend.h     | 12 ++++++++----
>  include/linux/memcontrol.h           |  7 +++++++
>  mm/memcontrol.c                      |  2 +-
>  9 files changed, 36 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
> index 63a1ca4b9dee..eb5c41284649 100644
> --- a/fs/notify/dnotify/dnotify.c
> +++ b/fs/notify/dnotify/dnotify.c
> @@ -384,8 +384,9 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
>  
>  static int __init dnotify_init(void)
>  {
> -	dnotify_struct_cache = KMEM_CACHE(dnotify_struct, SLAB_PANIC);
> -	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC);
> +	dnotify_struct_cache = KMEM_CACHE(dnotify_struct,
> +					  SLAB_PANIC|SLAB_ACCOUNT);
> +	dnotify_mark_cache = KMEM_CACHE(dnotify_mark, SLAB_PANIC|SLAB_ACCOUNT);
>  
>  	dnotify_group = fsnotify_alloc_group(&dnotify_fsnotify_ops);
>  	if (IS_ERR(dnotify_group))
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index d51e1bb781cf..cb6670bed289 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -157,14 +157,16 @@ struct fanotify_event_info *fanotify_alloc_event(struct fsnotify_group *group,
>  	if (fanotify_is_perm_event(mask)) {
>  		struct fanotify_perm_event_info *pevent;
>  
> -		pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
> +		pevent = kmem_cache_alloc_memcg(fanotify_perm_event_cachep, gfp,
> +						group->memcg);
>  		if (!pevent)
>  			return NULL;
>  		event = &pevent->fae;
>  		pevent->response = 0;
>  		goto init;
>  	}
> -	event = kmem_cache_alloc(fanotify_event_cachep, gfp);
> +	event = kmem_cache_alloc_memcg(fanotify_event_cachep, gfp,
> +				       group->memcg);
>  	if (!event)
>  		return NULL;
>  init: __maybe_unused
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 72e367822efb..6015bbaaa319 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -16,6 +16,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/compat.h>
>  #include <linux/sched/signal.h>
> +#include <linux/memcontrol.h>
>  
>  #include <asm/ioctls.h>
>  
> @@ -756,6 +757,7 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags)
>  
>  	group->fanotify_data.user = user;
>  	atomic_inc(&user->fanotify_listeners);
> +	group->memcg = get_mem_cgroup_from_mm(current->mm);
>  
>  	oevent = fanotify_alloc_event(group, NULL, FS_Q_OVERFLOW, NULL);
>  	if (unlikely(!oevent)) {
> @@ -951,7 +953,8 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark,
>   */
>  static int __init fanotify_user_setup(void)
>  {
> -	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, SLAB_PANIC);
> +	fanotify_mark_cache = KMEM_CACHE(fsnotify_mark,
> +					 SLAB_PANIC|SLAB_ACCOUNT);
>  	fanotify_event_cachep = KMEM_CACHE(fanotify_event_info, SLAB_PANIC);
>  	if (IS_ENABLED(CONFIG_FANOTIFY_ACCESS_PERMISSIONS)) {
>  		fanotify_perm_event_cachep =
> diff --git a/fs/notify/group.c b/fs/notify/group.c
> index b7a4b6a69efa..df14a66ce067 100644
> --- a/fs/notify/group.c
> +++ b/fs/notify/group.c
> @@ -22,6 +22,7 @@
>  #include <linux/srcu.h>
>  #include <linux/rculist.h>
>  #include <linux/wait.h>
> +#include <linux/memcontrol.h>
>  
>  #include <linux/fsnotify_backend.h>
>  #include "fsnotify.h"
> @@ -36,6 +37,9 @@ static void fsnotify_final_destroy_group(struct fsnotify_group *group)
>  	if (group->ops->free_group_priv)
>  		group->ops->free_group_priv(group);
>  
> +	if (group->memcg)
> +		css_put(&group->memcg->css);
> +
>  	kfree(group);
>  }
>  
> diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
> index 40dedb37a1f3..b184bff93d02 100644
> --- a/fs/notify/inotify/inotify_fsnotify.c
> +++ b/fs/notify/inotify/inotify_fsnotify.c
> @@ -98,7 +98,7 @@ int inotify_handle_event(struct fsnotify_group *group,
>  	i_mark = container_of(inode_mark, struct inotify_inode_mark,
>  			      fsn_mark);
>  
> -	event = kmalloc(alloc_len, GFP_KERNEL);
> +	event = kmalloc_memcg(alloc_len, GFP_KERNEL, group->memcg);
>  	if (unlikely(!event)) {
>  		/*
>  		 * Treat lost event due to ENOMEM the same way as queue
> diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
> index 8f17719842ec..d9e4b243c973 100644
> --- a/fs/notify/inotify/inotify_user.c
> +++ b/fs/notify/inotify/inotify_user.c
> @@ -38,6 +38,7 @@
>  #include <linux/uaccess.h>
>  #include <linux/poll.h>
>  #include <linux/wait.h>
> +#include <linux/memcontrol.h>
>  
>  #include "inotify.h"
>  #include "../fdinfo.h"
> @@ -632,6 +633,7 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
>  	oevent->name_len = 0;
>  
>  	group->max_events = max_events;
> +	group->memcg = get_mem_cgroup_from_mm(current->mm);
>  
>  	spin_lock_init(&group->inotify_data.idr_lock);
>  	idr_init(&group->inotify_data.idr);
> @@ -799,7 +801,8 @@ static int __init inotify_user_setup(void)
>  
>  	BUG_ON(hweight32(ALL_INOTIFY_BITS) != 21);
>  
> -	inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark, SLAB_PANIC);
> +	inotify_inode_mark_cachep = KMEM_CACHE(inotify_inode_mark,
> +					       SLAB_PANIC|SLAB_ACCOUNT);
>  
>  	inotify_max_queued_events = 16384;
>  	init_user_ns.ucount_max[UCOUNT_INOTIFY_INSTANCES] = 128;
> diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
> index 9f1edb92c97e..81bd86dfa2cd 100644
> --- a/include/linux/fsnotify_backend.h
> +++ b/include/linux/fsnotify_backend.h
> @@ -84,6 +84,8 @@ struct fsnotify_event_private_data;
>  struct fsnotify_fname;
>  struct fsnotify_iter_info;
>  
> +struct mem_cgroup;
> +
>  /*
>   * Each group much define these ops.  The fsnotify infrastructure will call
>   * these operations for each relevant group.
> @@ -129,6 +131,8 @@ struct fsnotify_event {
>   * everything will be cleaned up.
>   */
>  struct fsnotify_group {
> +	const struct fsnotify_ops *ops;	/* how this group handles things */
> +
>  	/*
>  	 * How the refcnt is used is up to each group.  When the refcnt hits 0
>  	 * fsnotify will clean up all of the resources associated with this group.
> @@ -139,8 +143,6 @@ struct fsnotify_group {
>  	 */
>  	refcount_t refcnt;		/* things with interest in this group */
>  
> -	const struct fsnotify_ops *ops;	/* how this group handles things */
> -
>  	/* needed to send notification to userspace */
>  	spinlock_t notification_lock;		/* protect the notification_list */
>  	struct list_head notification_list;	/* list of event_holder this group needs to send to userspace */
> @@ -162,6 +164,8 @@ struct fsnotify_group {
>  	atomic_t num_marks;		/* 1 for each mark and 1 for not being
>  					 * past the point of no return when freeing
>  					 * a group */
> +	atomic_t user_waits;		/* Number of tasks waiting for user
> +					 * response */
>  	struct list_head marks_list;	/* all inode marks for this group */
>  
>  	struct fasync_struct *fsn_fa;    /* async notification */
> @@ -169,8 +173,8 @@ struct fsnotify_group {
>  	struct fsnotify_event *overflow_event;	/* Event we queue when the
>  						 * notification list is too
>  						 * full */
> -	atomic_t user_waits;		/* Number of tasks waiting for user
> -					 * response */
> +
> +	struct mem_cgroup *memcg;	/* memcg to charge allocations */
>  
>  	/* groups can define private fields here or use the void *private */
>  	union {
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index c79cdf9f8138..4525b4404a9e 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -352,6 +352,8 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
>  	return css ? container_of(css, struct mem_cgroup, css) : NULL;
>  }
>  
> +struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
> +
>  static inline void mem_cgroup_put(struct mem_cgroup *memcg)
>  {
>  	css_put(&memcg->css);
> @@ -809,6 +811,11 @@ static inline bool task_in_mem_cgroup(struct task_struct *task,
>  	return true;
>  }
>  
> +static inline struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
> +{
> +	return NULL;
> +}
> +
>  static inline void mem_cgroup_put(struct mem_cgroup *memcg)
>  {
>  }
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5a2acfbc4962..3801ac1fcfbc 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -678,7 +678,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>  }
>  EXPORT_SYMBOL(mem_cgroup_from_task);
>  
> -static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
> +struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
>  {
>  	struct mem_cgroup *memcg = NULL;
>  
> -- 
> 2.16.2.395.g2e18187dfd-goog
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

[patch -mm] mm: memcg: remote memcg charging for kmem allocations fix

[David Rientjes]

fix build warning for CONFIG_SLOB:

mm/memcontrol.c:706:27: warning: 'get_mem_cgroup' defined but not used [-Wunused-function]
static struct mem_cgroup *get_mem_cgroup(struct mem_cgroup *memcg)

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: David Rientjes <rientjes@google.com>
---
 mm/memcontrol.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -701,15 +701,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
 	return memcg;
 }
 
-static struct mem_cgroup *get_mem_cgroup(struct mem_cgroup *memcg)
-{
-	rcu_read_lock();
-	if (!css_tryget_online(&memcg->css))
-		memcg = NULL;
-	rcu_read_unlock();
-	return memcg;
-}
-
 /**
  * mem_cgroup_iter - iterate over memory cgroup hierarchy
  * @root: hierarchy root
@@ -2128,6 +2119,15 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg,
 }
 
 #ifndef CONFIG_SLOB
+static struct mem_cgroup *get_mem_cgroup(struct mem_cgroup *memcg)
+{
+	rcu_read_lock();
+	if (!css_tryget_online(&memcg->css))
+		memcg = NULL;
+	rcu_read_unlock();
+	return memcg;
+}
+
 static int memcg_alloc_cache_id(void)
 {
 	int id, size;