The patch titled
Subject: fs: fsnotify: account fsnotify metadata to kmemcg
has been added to the -mm tree. Its filename is
fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: fs: fsnotify: account fsnotify metadata to kmemcg
Patch series "Directed kmem charging", v8.
The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs. All the
kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited by
the job's limit.
The kernel memory can only be charged to the memcg of the process in whose
context kernel memory was allocated. However there are cases where the
allocated kernel memory should be charged to the memcg different from the
current processes's memcg. This patch series contains two such concrete
use-cases i.e. fsnotify and buffer_head.
The fsnotify event objects can consume a lot of system memory for large or
unlimited queues if there is either no or slow listener. The events are
allocated in the context of the event producer. However they should be
charged to the event consumer. Similarly the buffer_head objects can be
allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.
To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg. In case of fsnotify events, the memcg of
the consumer can be used for charging and for buffer_head, the memcg of
the page can be charged. For directed charging, the caller can use the
scope API memalloc_[un]use_memcg() to specify the memcg to charge for all
the __GFP_ACCOUNT allocations within the scope.
This patch (of 2):
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.
However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer. This patch introduces remote memcg charging API which the
producer can use to charge the allocations 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.
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Amir Goldstein <amir73il@xxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Roman Gushchin <guro@xxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN fs/notify/dnotify/dnotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/dnotify/dnotify.c
--- a/fs/notify/dnotify/dnotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/fs/notify/dnotify/dnotify.c
@@ -384,8 +384,9 @@ out_err:
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 -puN fs/notify/fanotify/fanotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/fanotify/fanotify.c
--- a/fs/notify/fanotify/fanotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/fs/notify/fanotify/fanotify.c
@@ -11,6 +11,7 @@
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/audit.h>
+#include <linux/sched/mm.h>
#include "fanotify.h"
@@ -140,8 +141,8 @@ struct fanotify_event_info *fanotify_all
struct inode *inode, u32 mask,
const struct path *path)
{
- struct fanotify_event_info *event;
- gfp_t gfp = GFP_KERNEL;
+ struct fanotify_event_info *event = NULL;
+ gfp_t gfp = GFP_KERNEL | __GFP_ACCOUNT;
/*
* For queues with unlimited length lost events are not expected and
@@ -151,19 +152,22 @@ struct fanotify_event_info *fanotify_all
if (group->max_events == UINT_MAX)
gfp |= __GFP_NOFAIL;
+ /* Whoever is interested in the event, pays for the allocation. */
+ memalloc_use_memcg(group->memcg);
+
if (fanotify_is_perm_event(mask)) {
struct fanotify_perm_event_info *pevent;
pevent = kmem_cache_alloc(fanotify_perm_event_cachep, gfp);
if (!pevent)
- return NULL;
+ goto out;
event = &pevent->fae;
pevent->response = 0;
goto init;
}
event = kmem_cache_alloc(fanotify_event_cachep, gfp);
if (!event)
- return NULL;
+ goto out;
init: __maybe_unused
fsnotify_init_event(&event->fse, inode, mask);
event->tgid = get_pid(task_tgid(current));
@@ -174,6 +178,8 @@ init: __maybe_unused
event->path.mnt = NULL;
event->path.dentry = NULL;
}
+out:
+ memalloc_unuse_memcg();
return event;
}
diff -puN fs/notify/fanotify/fanotify_user.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/fanotify/fanotify_user.c
--- a/fs/notify/fanotify/fanotify_user.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/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
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)) {
@@ -957,7 +959,8 @@ 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 -puN fs/notify/group.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/group.c
--- a/fs/notify/group.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/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 +37,8 @@ static void fsnotify_final_destroy_group
if (group->ops->free_group_priv)
group->ops->free_group_priv(group);
+ mem_cgroup_put(group->memcg);
+
kfree(group);
}
diff -puN fs/notify/inotify/inotify_fsnotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/inotify/inotify_fsnotify.c
--- a/fs/notify/inotify/inotify_fsnotify.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/fs/notify/inotify/inotify_fsnotify.c
@@ -31,6 +31,7 @@
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/sched/user.h>
+#include <linux/sched/mm.h>
#include "inotify.h"
@@ -98,7 +99,11 @@ int inotify_handle_event(struct fsnotify
i_mark = container_of(inode_mark, struct inotify_inode_mark,
fsn_mark);
- event = kmalloc(alloc_len, GFP_KERNEL);
+ /* Whoever is interested in the event, pays for the allocation. */
+ memalloc_use_memcg(group->memcg);
+ event = kmalloc(alloc_len, GFP_KERNEL | __GFP_ACCOUNT);
+ memalloc_unuse_memcg();
+
if (unlikely(!event)) {
/*
* Treat lost event due to ENOMEM the same way as queue
diff -puN fs/notify/inotify/inotify_user.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg fs/notify/inotify/inotify_user.c
--- a/fs/notify/inotify/inotify_user.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/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"
@@ -636,6 +637,7 @@ static struct fsnotify_group *inotify_ne
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);
@@ -808,7 +810,8 @@ static int __init inotify_user_setup(voi
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 -puN include/linux/fsnotify_backend.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg include/linux/fsnotify_backend.h
--- a/include/linux/fsnotify_backend.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/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.
@@ -127,6 +129,8 @@ 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.
@@ -137,8 +141,6 @@ 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 */
@@ -160,6 +162,8 @@ 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 */
@@ -167,8 +171,8 @@ 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 -puN include/linux/memcontrol.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg include/linux/memcontrol.h
--- a/include/linux/memcontrol.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/include/linux/memcontrol.h
@@ -370,6 +370,8 @@ struct lruvec *mem_cgroup_page_lruvec(st
bool task_in_mem_cgroup(struct task_struct *task, struct mem_cgroup *memcg);
struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm);
+
static inline
struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
return css ? container_of(css, struct mem_cgroup, css) : NULL;
@@ -377,7 +379,8 @@ struct mem_cgroup *mem_cgroup_from_css(s
static inline void mem_cgroup_put(struct mem_cgroup *memcg)
{
- css_put(&memcg->css);
+ if (memcg)
+ css_put(&memcg->css);
}
#define mem_cgroup_from_counter(counter, member) \
@@ -842,6 +845,11 @@ static inline bool task_in_mem_cgroup(st
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 -puN include/linux/sched.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg include/linux/sched.h
--- a/include/linux/sched.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/include/linux/sched.h
@@ -1149,6 +1149,9 @@ 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 *active_memcg;
#endif
#ifdef CONFIG_UPROBES
diff -puN include/linux/sched/mm.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg include/linux/sched/mm.h
--- a/include/linux/sched/mm.h~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/include/linux/sched/mm.h
@@ -248,6 +248,43 @@ static inline void memalloc_noreclaim_re
current->flags = (current->flags & ~PF_MEMALLOC) | flags;
}
+#ifdef CONFIG_MEMCG
+/**
+ * memalloc_use_memcg - Starts the remote memcg charging scope.
+ * @memcg: memcg to charge.
+ *
+ * This function marks the beginning of the remote memcg charging scope. All the
+ * __GFP_ACCOUNT allocations till the end of the scope will be charged to the
+ * given memcg.
+ *
+ * NOTE: This function is not nesting safe.
+ */
+static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
+{
+ WARN_ON_ONCE(current->active_memcg);
+ current->active_memcg = memcg;
+}
+
+/**
+ * memalloc_unuse_memcg - Ends the remote memcg charging scope.
+ *
+ * This function marks the end of the remote memcg charging scope started by
+ * memalloc_use_memcg().
+ */
+static inline void memalloc_unuse_memcg(void)
+{
+ current->active_memcg = NULL;
+}
+#else
+static inline void memalloc_use_memcg(struct mem_cgroup *memcg)
+{
+}
+
+static inline void memalloc_unuse_memcg(void)
+{
+}
+#endif
+
#ifdef CONFIG_MEMBARRIER
enum {
MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY = (1U << 0),
diff -puN kernel/fork.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg kernel/fork.c
--- a/kernel/fork.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/kernel/fork.c
@@ -843,6 +843,9 @@ static struct task_struct *dup_task_stru
tsk->fail_nth = 0;
#endif
+#ifdef CONFIG_MEMCG
+ tsk->active_memcg = NULL;
+#endif
return tsk;
free_stack:
diff -puN mm/memcontrol.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg mm/memcontrol.c
--- a/mm/memcontrol.c~fs-fsnotify-account-fsnotify-metadata-to-kmemcg
+++ a/mm/memcontrol.c
@@ -678,9 +678,20 @@ struct mem_cgroup *mem_cgroup_from_task(
}
EXPORT_SYMBOL(mem_cgroup_from_task);
-static struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
+/**
+ * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg.
+ * @mm: mm from which memcg should be extracted. It can be NULL.
+ *
+ * Obtain a reference on mm->memcg and returns it if successful. Otherwise
+ * root_mem_cgroup is returned. However if mem_cgroup is disabled, NULL is
+ * returned.
+ */
+struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm)
{
- struct mem_cgroup *memcg = NULL;
+ struct mem_cgroup *memcg;
+
+ if (mem_cgroup_disabled())
+ return NULL;
rcu_read_lock();
do {
@@ -700,6 +711,24 @@ static struct mem_cgroup *get_mem_cgroup
rcu_read_unlock();
return memcg;
}
+EXPORT_SYMBOL(get_mem_cgroup_from_mm);
+
+/**
+ * If current->active_memcg is non-NULL, do not fallback to current->mm->memcg.
+ */
+static __always_inline struct mem_cgroup *get_mem_cgroup_from_current(void)
+{
+ if (unlikely(current->active_memcg)) {
+ struct mem_cgroup *memcg = root_mem_cgroup;
+
+ rcu_read_lock();
+ if (css_tryget_online(¤t->active_memcg->css))
+ memcg = current->active_memcg;
+ rcu_read_unlock();
+ return memcg;
+ }
+ return get_mem_cgroup_from_mm(current->mm);
+}
/**
* mem_cgroup_iter - iterate over memory cgroup hierarchy
@@ -2261,7 +2290,7 @@ struct kmem_cache *memcg_kmem_get_cache(
if (current->memcg_kmem_skip_account)
return cachep;
- memcg = get_mem_cgroup_from_mm(current->mm);
+ memcg = get_mem_cgroup_from_current();
kmemcg_id = READ_ONCE(memcg->kmemcg_id);
if (kmemcg_id < 0)
goto out;
@@ -2345,7 +2374,7 @@ int memcg_kmem_charge(struct page *page,
if (memcg_kmem_bypass())
return 0;
- memcg = get_mem_cgroup_from_mm(current->mm);
+ memcg = get_mem_cgroup_from_current();
if (!mem_cgroup_is_root(memcg)) {
ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
if (!ret)
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
slub-track-number-of-slabs-irrespective-of-config_slub_debug.patch
fs-fsnotify-account-fsnotify-metadata-to-kmemcg.patch
fs-mm-account-buffer_head-to-kmemcg.patch
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