[PATCH v3 1/4] mm: rename page_counter's count/limit into usage/max

From: Roman Gushchin
Date: Thu Apr 05 2018 - 15:00:45 EST

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This patch renames struct page_counter fields:
count -> usage
limit -> max

and the corresponding functions:
page_counter_limit() -> page_counter_set_max()
mem_cgroup_get_limit() -> mem_cgroup_get_max()
mem_cgroup_resize_limit() -> mem_cgroup_resize_max()
memcg_update_kmem_limit() -> memcg_update_kmem_max()
memcg_update_tcp_limit() -> memcg_update_tcp_max()

The idea behind this renaming is to have the direct matching
between memory cgroup knobs (low, high, max) and page_counters API.

This is pure renaming, this patch doesn't bring any functional change.

Signed-off-by: Roman Gushchin <guro@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: kernel-team@xxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: cgroups@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
include/linux/memcontrol.h | 4 +-
include/linux/page_counter.h | 12 ++---
mm/hugetlb_cgroup.c | 6 +--
mm/memcontrol.c | 112 +++++++++++++++++++++----------------------
mm/oom_kill.c | 2 +-
mm/page_counter.c | 28 +++++------
6 files changed, 82 insertions(+), 82 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 44422e1d3def..caa31cc09e7e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -475,7 +475,7 @@ unsigned long mem_cgroup_get_zone_lru_size(struct lruvec *lruvec,

void mem_cgroup_handle_over_high(void);

-unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg);
+unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg);

void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
struct task_struct *p);
@@ -882,7 +882,7 @@ mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg,
return 0;
}

-static inline unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
+static inline unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
{
return 0;
}
diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
index c15ab80ad32d..94029dad9317 100644
--- a/include/linux/page_counter.h
+++ b/include/linux/page_counter.h
@@ -7,8 +7,8 @@
#include <asm/page.h>

struct page_counter {
- atomic_long_t count;
- unsigned long limit;
+ atomic_long_t usage;
+ unsigned long max;
struct page_counter *parent;

/* legacy */
@@ -25,14 +25,14 @@ struct page_counter {
static inline void page_counter_init(struct page_counter *counter,
struct page_counter *parent)
{
- atomic_long_set(&counter->count, 0);
- counter->limit = PAGE_COUNTER_MAX;
+ atomic_long_set(&counter->usage, 0);
+ counter->max = PAGE_COUNTER_MAX;
counter->parent = parent;
}

static inline unsigned long page_counter_read(struct page_counter *counter)
{
- return atomic_long_read(&counter->count);
+ return atomic_long_read(&counter->usage);
}

void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages);
@@ -41,7 +41,7 @@ bool page_counter_try_charge(struct page_counter *counter,
unsigned long nr_pages,
struct page_counter **fail);
void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages);
-int page_counter_limit(struct page_counter *counter, unsigned long limit);
+int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages);
int page_counter_memparse(const char *buf, const char *max,
unsigned long *nr_pages);

diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
index eec1150125b9..68c2f2f3c05b 100644
--- a/mm/hugetlb_cgroup.c
+++ b/mm/hugetlb_cgroup.c
@@ -84,7 +84,7 @@ static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,

limit = round_down(PAGE_COUNTER_MAX,
1 << huge_page_order(&hstates[idx]));
- ret = page_counter_limit(counter, limit);
+ ret = page_counter_set_max(counter, limit);
VM_BUG_ON(ret);
}
}
@@ -273,7 +273,7 @@ static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
case RES_USAGE:
return (u64)page_counter_read(counter) * PAGE_SIZE;
case RES_LIMIT:
- return (u64)counter->limit * PAGE_SIZE;
+ return (u64)counter->max * PAGE_SIZE;
case RES_MAX_USAGE:
return (u64)counter->watermark * PAGE_SIZE;
case RES_FAILCNT:
@@ -306,7 +306,7 @@ static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
switch (MEMFILE_ATTR(of_cft(of)->private)) {
case RES_LIMIT:
mutex_lock(&hugetlb_limit_mutex);
- ret = page_counter_limit(&h_cg->hugepage[idx], nr_pages);
+ ret = page_counter_set_max(&h_cg->hugepage[idx], nr_pages);
mutex_unlock(&hugetlb_limit_mutex);
break;
default:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 18dda3f113bd..50d1ad6a8fdb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1033,13 +1033,13 @@ static unsigned long mem_cgroup_margin(struct mem_cgroup *memcg)
unsigned long limit;

count = page_counter_read(&memcg->memory);
- limit = READ_ONCE(memcg->memory.limit);
+ limit = READ_ONCE(memcg->memory.max);
if (count < limit)
margin = limit - count;

if (do_memsw_account()) {
count = page_counter_read(&memcg->memsw);
- limit = READ_ONCE(memcg->memsw.limit);
+ limit = READ_ONCE(memcg->memsw.max);
if (count <= limit)
margin = min(margin, limit - count);
else
@@ -1147,13 +1147,13 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)

pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memory)),
- K((u64)memcg->memory.limit), memcg->memory.failcnt);
+ K((u64)memcg->memory.max), memcg->memory.failcnt);
pr_info("memory+swap: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->memsw)),
- K((u64)memcg->memsw.limit), memcg->memsw.failcnt);
+ K((u64)memcg->memsw.max), memcg->memsw.failcnt);
pr_info("kmem: usage %llukB, limit %llukB, failcnt %lu\n",
K((u64)page_counter_read(&memcg->kmem)),
- K((u64)memcg->kmem.limit), memcg->kmem.failcnt);
+ K((u64)memcg->kmem.max), memcg->kmem.failcnt);

for_each_mem_cgroup_tree(iter, memcg) {
pr_info("Memory cgroup stats for ");
@@ -1178,21 +1178,21 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
/*
* Return the memory (and swap, if configured) limit for a memcg.
*/
-unsigned long mem_cgroup_get_limit(struct mem_cgroup *memcg)
+unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
{
- unsigned long limit;
+ unsigned long max;

- limit = memcg->memory.limit;
+ max = memcg->memory.max;
if (mem_cgroup_swappiness(memcg)) {
- unsigned long memsw_limit;
- unsigned long swap_limit;
+ unsigned long memsw_max;
+ unsigned long swap_max;

- memsw_limit = memcg->memsw.limit;
- swap_limit = memcg->swap.limit;
- swap_limit = min(swap_limit, (unsigned long)total_swap_pages);
- limit = min(limit + swap_limit, memsw_limit);
+ memsw_max = memcg->memsw.max;
+ swap_max = memcg->swap.max;
+ swap_max = min(swap_max, (unsigned long)total_swap_pages);
+ max = min(max + swap_max, memsw_max);
}
- return limit;
+ return max;
}

static bool mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
@@ -2458,10 +2458,10 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
}
#endif

-static DEFINE_MUTEX(memcg_limit_mutex);
+static DEFINE_MUTEX(memcg_max_mutex);

-static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
- unsigned long limit, bool memsw)
+static int mem_cgroup_resize_max(struct mem_cgroup *memcg,
+ unsigned long max, bool memsw)
{
bool enlarge = false;
int ret;
@@ -2474,22 +2474,22 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
break;
}

- mutex_lock(&memcg_limit_mutex);
+ mutex_lock(&memcg_max_mutex);
/*
* Make sure that the new limit (memsw or memory limit) doesn't
- * break our basic invariant rule memory.limit <= memsw.limit.
+ * break our basic invariant rule memory.max <= memsw.max.
*/
- limits_invariant = memsw ? limit >= memcg->memory.limit :
- limit <= memcg->memsw.limit;
+ limits_invariant = memsw ? max >= memcg->memory.max :
+ max <= memcg->memsw.max;
if (!limits_invariant) {
- mutex_unlock(&memcg_limit_mutex);
+ mutex_unlock(&memcg_max_mutex);
ret = -EINVAL;
break;
}
- if (limit > counter->limit)
+ if (max > counter->max)
enlarge = true;
- ret = page_counter_limit(counter, limit);
- mutex_unlock(&memcg_limit_mutex);
+ ret = page_counter_set_max(counter, max);
+ mutex_unlock(&memcg_max_mutex);

if (!ret)
break;
@@ -2989,7 +2989,7 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
return (u64)mem_cgroup_usage(memcg, true) * PAGE_SIZE;
return (u64)page_counter_read(counter) * PAGE_SIZE;
case RES_LIMIT:
- return (u64)counter->limit * PAGE_SIZE;
+ return (u64)counter->max * PAGE_SIZE;
case RES_MAX_USAGE:
return (u64)counter->watermark * PAGE_SIZE;
case RES_FAILCNT:
@@ -3103,24 +3103,24 @@ static void memcg_free_kmem(struct mem_cgroup *memcg)
}
#endif /* !CONFIG_SLOB */

-static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
- unsigned long limit)
+static int memcg_update_kmem_max(struct mem_cgroup *memcg,
+ unsigned long max)
{
int ret;

- mutex_lock(&memcg_limit_mutex);
- ret = page_counter_limit(&memcg->kmem, limit);
- mutex_unlock(&memcg_limit_mutex);
+ mutex_lock(&memcg_max_mutex);
+ ret = page_counter_set_max(&memcg->kmem, max);
+ mutex_unlock(&memcg_max_mutex);
return ret;
}

-static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
+static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
{
int ret;

- mutex_lock(&memcg_limit_mutex);
+ mutex_lock(&memcg_max_mutex);

- ret = page_counter_limit(&memcg->tcpmem, limit);
+ ret = page_counter_set_max(&memcg->tcpmem, max);
if (ret)
goto out;

@@ -3145,7 +3145,7 @@ static int memcg_update_tcp_limit(struct mem_cgroup *memcg, unsigned long limit)
memcg->tcpmem_active = true;
}
out:
- mutex_unlock(&memcg_limit_mutex);
+ mutex_unlock(&memcg_max_mutex);
return ret;
}

@@ -3173,16 +3173,16 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
}
switch (MEMFILE_TYPE(of_cft(of)->private)) {
case _MEM:
- ret = mem_cgroup_resize_limit(memcg, nr_pages, false);
+ ret = mem_cgroup_resize_max(memcg, nr_pages, false);
break;
case _MEMSWAP:
- ret = mem_cgroup_resize_limit(memcg, nr_pages, true);
+ ret = mem_cgroup_resize_max(memcg, nr_pages, true);
break;
case _KMEM:
- ret = memcg_update_kmem_limit(memcg, nr_pages);
+ ret = memcg_update_kmem_max(memcg, nr_pages);
break;
case _TCP:
- ret = memcg_update_tcp_limit(memcg, nr_pages);
+ ret = memcg_update_tcp_max(memcg, nr_pages);
break;
}
break;
@@ -3358,8 +3358,8 @@ static int memcg_stat_show(struct seq_file *m, void *v)
/* Hierarchical information */
memory = memsw = PAGE_COUNTER_MAX;
for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) {
- memory = min(memory, mi->memory.limit);
- memsw = min(memsw, mi->memsw.limit);
+ memory = min(memory, mi->memory.max);
+ memsw = min(memsw, mi->memsw.max);
}
seq_printf(m, "hierarchical_memory_limit %llu\n",
(u64)memory * PAGE_SIZE);
@@ -3858,7 +3858,7 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
*pheadroom = PAGE_COUNTER_MAX;

while ((parent = parent_mem_cgroup(memcg))) {
- unsigned long ceiling = min(memcg->memory.limit, memcg->high);
+ unsigned long ceiling = min(memcg->memory.max, memcg->high);
unsigned long used = page_counter_read(&memcg->memory);

*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
@@ -4548,12 +4548,12 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(css);

- page_counter_limit(&memcg->memory, PAGE_COUNTER_MAX);
- page_counter_limit(&memcg->swap, PAGE_COUNTER_MAX);
- page_counter_limit(&memcg->memsw, PAGE_COUNTER_MAX);
- page_counter_limit(&memcg->kmem, PAGE_COUNTER_MAX);
- page_counter_limit(&memcg->tcpmem, PAGE_COUNTER_MAX);
memcg->low = 0;
+ page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX);
+ page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX);
+ page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX);
+ page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX);
+ page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
memcg->high = PAGE_COUNTER_MAX;
memcg->soft_limit = PAGE_COUNTER_MAX;
memcg_wb_domain_size_changed(memcg);
@@ -5360,7 +5360,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
static int memory_max_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
- unsigned long max = READ_ONCE(memcg->memory.limit);
+ unsigned long max = READ_ONCE(memcg->memory.max);

if (max == PAGE_COUNTER_MAX)
seq_puts(m, "max\n");
@@ -5384,7 +5384,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of,
if (err)
return err;

- xchg(&memcg->memory.limit, max);
+ xchg(&memcg->memory.max, max);

for (;;) {
unsigned long nr_pages = page_counter_read(&memcg->memory);
@@ -6331,7 +6331,7 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
return nr_swap_pages;
for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
nr_swap_pages = min_t(long, nr_swap_pages,
- READ_ONCE(memcg->swap.limit) -
+ READ_ONCE(memcg->swap.max) -
page_counter_read(&memcg->swap));
return nr_swap_pages;
}
@@ -6352,7 +6352,7 @@ bool mem_cgroup_swap_full(struct page *page)
return false;

for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
- if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.limit)
+ if (page_counter_read(&memcg->swap) * 2 >= memcg->swap.max)
return true;

return false;
@@ -6386,7 +6386,7 @@ static u64 swap_current_read(struct cgroup_subsys_state *css,
static int swap_max_show(struct seq_file *m, void *v)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
- unsigned long max = READ_ONCE(memcg->swap.limit);
+ unsigned long max = READ_ONCE(memcg->swap.max);

if (max == PAGE_COUNTER_MAX)
seq_puts(m, "max\n");
@@ -6408,9 +6408,9 @@ static ssize_t swap_max_write(struct kernfs_open_file *of,
if (err)
return err;

- mutex_lock(&memcg_limit_mutex);
- err = page_counter_limit(&memcg->swap, max);
- mutex_unlock(&memcg_limit_mutex);
+ mutex_lock(&memcg_max_mutex);
+ err = page_counter_set_max(&memcg->swap, max);
+ mutex_unlock(&memcg_max_mutex);
if (err)
return err;

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index dfd370526909..a420a703b8d5 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -256,7 +256,7 @@ static enum oom_constraint constrained_alloc(struct oom_control *oc)
int nid;

if (is_memcg_oom(oc)) {
- oc->totalpages = mem_cgroup_get_limit(oc->memcg) ?: 1;
+ oc->totalpages = mem_cgroup_get_max(oc->memcg) ?: 1;
return CONSTRAINT_MEMCG;
}

diff --git a/mm/page_counter.c b/mm/page_counter.c
index 2a8df3ad60a4..41937c9a9d11 100644
--- a/mm/page_counter.c
+++ b/mm/page_counter.c
@@ -22,7 +22,7 @@ void page_counter_cancel(struct page_counter *counter, unsigned long nr_pages)
{
long new;

- new = atomic_long_sub_return(nr_pages, &counter->count);
+ new = atomic_long_sub_return(nr_pages, &counter->usage);
/* More uncharges than charges? */
WARN_ON_ONCE(new < 0);
}
@@ -41,7 +41,7 @@ void page_counter_charge(struct page_counter *counter, unsigned long nr_pages)
for (c = counter; c; c = c->parent) {
long new;

- new = atomic_long_add_return(nr_pages, &c->count);
+ new = atomic_long_add_return(nr_pages, &c->usage);
/*
* This is indeed racy, but we can live with some
* inaccuracy in the watermark.
@@ -82,9 +82,9 @@ bool page_counter_try_charge(struct page_counter *counter,
* we either see the new limit or the setter sees the
* counter has changed and retries.
*/
- new = atomic_long_add_return(nr_pages, &c->count);
- if (new > c->limit) {
- atomic_long_sub(nr_pages, &c->count);
+ new = atomic_long_add_return(nr_pages, &c->usage);
+ if (new > c->max) {
+ atomic_long_sub(nr_pages, &c->usage);
/*
* This is racy, but we can live with some
* inaccuracy in the failcnt.
@@ -123,20 +123,20 @@ void page_counter_uncharge(struct page_counter *counter, unsigned long nr_pages)
}

/**
- * page_counter_limit - limit the number of pages allowed
+ * page_counter_set_max - set the maximum number of pages allowed
* @counter: counter
- * @limit: limit to set
+ * @nr_pages: limit to set
*
* Returns 0 on success, -EBUSY if the current number of pages on the
* counter already exceeds the specified limit.
*
* The caller must serialize invocations on the same counter.
*/
-int page_counter_limit(struct page_counter *counter, unsigned long limit)
+int page_counter_set_max(struct page_counter *counter, unsigned long nr_pages)
{
for (;;) {
unsigned long old;
- long count;
+ long usage;

/*
* Update the limit while making sure that it's not
@@ -149,17 +149,17 @@ int page_counter_limit(struct page_counter *counter, unsigned long limit)
* the limit, so if it sees the old limit, we see the
* modified counter and retry.
*/
- count = atomic_long_read(&counter->count);
+ usage = atomic_long_read(&counter->usage);

- if (count > limit)
+ if (usage > nr_pages)
return -EBUSY;

- old = xchg(&counter->limit, limit);
+ old = xchg(&counter->max, nr_pages);

- if (atomic_long_read(&counter->count) <= count)
+ if (atomic_long_read(&counter->usage) <= usage)
return 0;

- counter->limit = old;
+ counter->max = old;
cond_resched();
}
}
--
2.14.3

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