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mm: memcontrol: rein in the CONFIG space madness
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What CONFIG_INET and CONFIG_LEGACY_KMEM guard inside the memory
controller code is insignificant, having these conditionals is not
worth the complication and fragility that comes with them.

[[email protected]: rework mem_cgroup_css_free() statement ordering]
Signed-off-by: Johannes Weiner <[email protected]>
Cc: Michal Hocko <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@hnaz @torvalds
hnaz authored and torvalds committed Jan 21, 2016
1 parent d55f90b commit d886f4e
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Showing 4 changed files with 12 additions and 78 deletions.
14 changes: 5 additions & 9 deletions include/linux/memcontrol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -233,9 +233,11 @@ struct mem_cgroup {
*/
struct mem_cgroup_stat_cpu __percpu *stat;

#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
unsigned long socket_pressure;

/* Legacy tcp memory accounting */
struct cg_proto tcp_mem;
#endif

#ifndef CONFIG_SLOB
/* Index in the kmem_cache->memcg_params.memcg_caches array */
int kmemcg_id;
Expand All @@ -254,10 +256,6 @@ struct mem_cgroup {
struct wb_domain cgwb_domain;
#endif

#ifdef CONFIG_INET
unsigned long socket_pressure;
#endif

/* List of events which userspace want to receive */
struct list_head event_list;
spinlock_t event_list_lock;
Expand Down Expand Up @@ -712,15 +710,13 @@ void sock_update_memcg(struct sock *sk);
void sock_release_memcg(struct sock *sk);
bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages);
#if defined(CONFIG_MEMCG) && defined(CONFIG_INET)
#ifdef CONFIG_MEMCG
extern struct static_key_false memcg_sockets_enabled_key;
#define mem_cgroup_sockets_enabled static_branch_unlikely(&memcg_sockets_enabled_key)
static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
{
#ifdef CONFIG_MEMCG_LEGACY_KMEM
if (memcg->tcp_mem.memory_pressure)
return true;
#endif
do {
if (time_before(jiffies, memcg->socket_pressure))
return true;
Expand Down
21 changes: 3 additions & 18 deletions init/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -964,20 +964,6 @@ config MEMCG_SWAP_ENABLED
For those who want to have the feature enabled by default should
select this option (if, for some reason, they need to disable it
then swapaccount=0 does the trick).
config MEMCG_LEGACY_KMEM
bool
config MEMCG_KMEM
bool "Legacy Memory Resource Controller Kernel Memory accounting"
depends on MEMCG
depends on SLUB || SLAB
select MEMCG_LEGACY_KMEM
help
The Kernel Memory extension for Memory Resource Controller can limit
the amount of memory used by kernel objects in the system. Those are
fundamentally different from the entities handled by the standard
Memory Controller, which are page-based, and can be swapped. Users of
the kmem extension can use it to guarantee that no group of processes
will ever exhaust kernel resources alone.

config BLK_CGROUP
bool "IO controller"
Expand Down Expand Up @@ -1190,10 +1176,9 @@ config USER_NS
to provide different user info for different servers.

When user namespaces are enabled in the kernel it is
recommended that the MEMCG and MEMCG_KMEM options also be
enabled and that user-space use the memory control groups to
limit the amount of memory a memory unprivileged users can
use.
recommended that the MEMCG option also be enabled and that
user-space use the memory control groups to limit the amount
of memory a memory unprivileged users can use.

If unsure, say N.

Expand Down
53 changes: 4 additions & 49 deletions mm/memcontrol.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2842,11 +2842,9 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
case _KMEM:
counter = &memcg->kmem;
break;
#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
case _TCP:
counter = &memcg->tcp_mem.memory_allocated;
break;
#endif
default:
BUG();
}
Expand Down Expand Up @@ -3006,7 +3004,6 @@ static void memcg_free_kmem(struct mem_cgroup *memcg)
}
#endif /* !CONFIG_SLOB */

#ifdef CONFIG_MEMCG_LEGACY_KMEM
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
unsigned long limit)
{
Expand All @@ -3024,16 +3021,7 @@ static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
mutex_unlock(&memcg_limit_mutex);
return ret;
}
#else
static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
unsigned long limit)
{
return -EINVAL;
}
#endif /* CONFIG_MEMCG_LEGACY_KMEM */


#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
{
int ret;
Expand Down Expand Up @@ -3068,12 +3056,6 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
mutex_unlock(&memcg_limit_mutex);
return ret;
}
#else
static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
{
return -EINVAL;
}
#endif /* CONFIG_MEMCG_LEGACY_KMEM && CONFIG_INET */

/*
* The user of this function is...
Expand Down Expand Up @@ -3136,11 +3118,9 @@ static ssize_t mem_cgroup_reset(struct kernfs_open_file *of, char *buf,
case _KMEM:
counter = &memcg->kmem;
break;
#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
case _TCP:
counter = &memcg->tcp_mem.memory_allocated;
break;
#endif
default:
BUG();
}
Expand Down Expand Up @@ -4094,7 +4074,6 @@ static struct cftype mem_cgroup_legacy_files[] = {
.seq_show = memcg_numa_stat_show,
},
#endif
#ifdef CONFIG_MEMCG_LEGACY_KMEM
{
.name = "kmem.limit_in_bytes",
.private = MEMFILE_PRIVATE(_KMEM, RES_LIMIT),
Expand Down Expand Up @@ -4127,7 +4106,6 @@ static struct cftype mem_cgroup_legacy_files[] = {
.seq_show = memcg_slab_show,
},
#endif
#ifdef CONFIG_INET
{
.name = "kmem.tcp.limit_in_bytes",
.private = MEMFILE_PRIVATE(_TCP, RES_LIMIT),
Expand All @@ -4151,8 +4129,6 @@ static struct cftype mem_cgroup_legacy_files[] = {
.write = mem_cgroup_reset,
.read_u64 = mem_cgroup_read_u64,
},
#endif
#endif
{ }, /* terminate */
};

Expand Down Expand Up @@ -4280,14 +4256,12 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
vmpressure_init(&memcg->vmpressure);
INIT_LIST_HEAD(&memcg->event_list);
spin_lock_init(&memcg->event_list_lock);
memcg->socket_pressure = jiffies;
#ifndef CONFIG_SLOB
memcg->kmemcg_id = -1;
#endif
#ifdef CONFIG_CGROUP_WRITEBACK
INIT_LIST_HEAD(&memcg->cgwb_list);
#endif
#ifdef CONFIG_INET
memcg->socket_pressure = jiffies;
#endif
return &memcg->css;

Expand Down Expand Up @@ -4321,10 +4295,8 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
memcg->soft_limit = PAGE_COUNTER_MAX;
page_counter_init(&memcg->memsw, &parent->memsw);
page_counter_init(&memcg->kmem, &parent->kmem);
#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
page_counter_init(&memcg->tcp_mem.memory_allocated,
&parent->tcp_mem.memory_allocated);
#endif

/*
* No need to take a reference to the parent because cgroup
Expand All @@ -4336,9 +4308,7 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
memcg->soft_limit = PAGE_COUNTER_MAX;
page_counter_init(&memcg->memsw, NULL);
page_counter_init(&memcg->kmem, NULL);
#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
page_counter_init(&memcg->tcp_mem.memory_allocated, NULL);
#endif
/*
* Deeper hierachy with use_hierarchy == false doesn't make
* much sense so let cgroup subsystem know about this
Expand All @@ -4353,10 +4323,8 @@ mem_cgroup_css_online(struct cgroup_subsys_state *css)
if (ret)
return ret;

#ifdef CONFIG_INET
if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
static_branch_inc(&memcg_sockets_enabled_key);
#endif

/*
* Make sure the memcg is initialized: mem_cgroup_iter()
Expand Down Expand Up @@ -4403,18 +4371,13 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);

#ifdef CONFIG_INET
if (cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_nosocket)
static_branch_dec(&memcg_sockets_enabled_key);
#endif

memcg_free_kmem(memcg);

#if defined(CONFIG_MEMCG_LEGACY_KMEM) && defined(CONFIG_INET)
if (memcg->tcp_mem.active)
static_branch_dec(&memcg_sockets_enabled_key);
#endif

memcg_free_kmem(memcg);
__mem_cgroup_free(memcg);
}

Expand Down Expand Up @@ -5613,8 +5576,6 @@ void mem_cgroup_replace_page(struct page *oldpage, struct page *newpage)
commit_charge(newpage, memcg, true);
}

#ifdef CONFIG_INET

DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key);
EXPORT_SYMBOL(memcg_sockets_enabled_key);

Expand All @@ -5640,10 +5601,8 @@ void sock_update_memcg(struct sock *sk)
memcg = mem_cgroup_from_task(current);
if (memcg == root_mem_cgroup)
goto out;
#ifdef CONFIG_MEMCG_LEGACY_KMEM
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) && !memcg->tcp_mem.active)
goto out;
#endif
if (css_tryget_online(&memcg->css))
sk->sk_memcg = memcg;
out:
Expand All @@ -5669,7 +5628,6 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
{
gfp_t gfp_mask = GFP_KERNEL;

#ifdef CONFIG_MEMCG_LEGACY_KMEM
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
struct page_counter *counter;

Expand All @@ -5682,7 +5640,7 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
memcg->tcp_mem.memory_pressure = 1;
return false;
}
#endif

/* Don't block in the packet receive path */
if (in_softirq())
gfp_mask = GFP_NOWAIT;
Expand All @@ -5701,19 +5659,16 @@ bool mem_cgroup_charge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
*/
void mem_cgroup_uncharge_skmem(struct mem_cgroup *memcg, unsigned int nr_pages)
{
#ifdef CONFIG_MEMCG_LEGACY_KMEM
if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
page_counter_uncharge(&memcg->tcp_mem.memory_allocated,
nr_pages);
return;
}
#endif

page_counter_uncharge(&memcg->memory, nr_pages);
css_put_many(&memcg->css, nr_pages);
}

#endif /* CONFIG_INET */

static int __init cgroup_memory(char *s)
{
char *token;
Expand Down
2 changes: 0 additions & 2 deletions mm/vmpressure.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -275,7 +275,6 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,

level = vmpressure_calc_level(scanned, reclaimed);

#ifdef CONFIG_INET
if (level > VMPRESSURE_LOW) {
/*
* Let the socket buffer allocator know that
Expand All @@ -287,7 +286,6 @@ void vmpressure(gfp_t gfp, struct mem_cgroup *memcg, bool tree,
*/
memcg->socket_pressure = jiffies + HZ;
}
#endif
}
}

Expand Down

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