Commit eccb52e7 authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds
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mm: memcontrol: prepare swap controller setup for integration 



A few cleanups to streamline the swap controller setup:

- Replace the do_swap_account flag with cgroup_memory_noswap. This
  brings it in line with other functionality that is usually available
  unless explicitly opted out of - nosocket, nokmem.

- Remove the really_do_swap_account flag that stores the boot option
  and is later used to switch the do_swap_account. It's not clear why
  this indirection is/was necessary. Use do_swap_account directly.

- Minor coding style polishing

Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Link: http://lkml.kernel.org/r/20200508183105.225460-15-hannes@cmpxchg.org


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f0e45fb4

include/linux/memcontrol.h

+1 −1
Original line number Diff line number Diff line
@@ -558,7 +558,7 @@ struct mem_cgroup *mem_cgroup_get_oom_group(struct task_struct *victim, 
void mem_cgroup_print_oom_group(struct mem_cgroup *memcg);



#ifdef CONFIG_MEMCG_SWAP

extern int do_swap_account;

extern bool cgroup_memory_noswap;

#endif



struct mem_cgroup *lock_page_memcg(struct page *page);

mm/memcontrol.c

+28 −31
Original line number Diff line number Diff line
@@ -83,10 +83,14 @@ static bool cgroup_memory_nokmem; 


/* Whether the swap controller is active */

#ifdef CONFIG_MEMCG_SWAP

int do_swap_account __read_mostly;

#ifdef CONFIG_MEMCG_SWAP_ENABLED

bool cgroup_memory_noswap __read_mostly;

#else

#define do_swap_account		0

#endif

bool cgroup_memory_noswap __read_mostly = 1;

#endif /* CONFIG_MEMCG_SWAP_ENABLED */

#else

#define cgroup_memory_noswap		1

#endif /* CONFIG_MEMCG_SWAP */



#ifdef CONFIG_CGROUP_WRITEBACK

static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
@@ -95,7 +99,7 @@ static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq); 
/* Whether legacy memory+swap accounting is active */

static bool do_memsw_account(void)

{

	return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account;

	return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_noswap;

}



#define THRESHOLDS_EVENTS_TARGET 128
@@ -6528,18 +6532,19 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, 
		/*

		 * Every swap fault against a single page tries to charge the

		 * page, bail as early as possible.  shmem_unuse() encounters

		 * already charged pages, too.  The USED bit is protected by

		 * the page lock, which serializes swap cache removal, which

		 * already charged pages, too.  page->mem_cgroup is protected

		 * by the page lock, which serializes swap cache removal, which

		 * in turn serializes uncharging.

		 */

		VM_BUG_ON_PAGE(!PageLocked(page), page);

		if (compound_head(page)->mem_cgroup)

			goto out;



		if (do_swap_account) {

		if (!cgroup_memory_noswap) {

			swp_entry_t ent = { .val = page_private(page), };

			unsigned short id = lookup_swap_cgroup_id(ent);

			unsigned short id;



			id = lookup_swap_cgroup_id(ent);

			rcu_read_lock();

			memcg = mem_cgroup_from_id(id);

			if (memcg && !css_tryget_online(&memcg->css))
@@ -7012,7 +7017,7 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) 
	struct mem_cgroup *memcg;

	unsigned short oldid;



	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account)

	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || cgroup_memory_noswap)

		return 0;



	memcg = page->mem_cgroup;
@@ -7056,7 +7061,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages) 
	struct mem_cgroup *memcg;

	unsigned short id;



	if (!do_swap_account)

	if (cgroup_memory_noswap)

		return;



	id = swap_cgroup_record(entry, 0, nr_pages);
@@ -7079,7 +7084,7 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg) 
{

	long nr_swap_pages = get_nr_swap_pages();



	if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))

	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))

		return nr_swap_pages;

	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))

		nr_swap_pages = min_t(long, nr_swap_pages,
@@ -7096,7 +7101,7 @@ bool mem_cgroup_swap_full(struct page *page) 


	if (vm_swap_full())

		return true;

	if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys))

	if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys))

		return false;



	memcg = page->mem_cgroup;
@@ -7114,22 +7119,15 @@ bool mem_cgroup_swap_full(struct page *page) 
	return false;

}



/* for remember boot option*/

#ifdef CONFIG_MEMCG_SWAP_ENABLED

static int really_do_swap_account __initdata = 1;

#else

static int really_do_swap_account __initdata;

#endif



static int __init enable_swap_account(char *s)

static int __init setup_swap_account(char *s)

{

	if (!strcmp(s, "1"))

		really_do_swap_account = 1;

		cgroup_memory_noswap = 0;

	else if (!strcmp(s, "0"))

		really_do_swap_account = 0;

		cgroup_memory_noswap = 1;

	return 1;

}

__setup("swapaccount=", enable_swap_account);

__setup("swapaccount=", setup_swap_account);



static u64 swap_current_read(struct cgroup_subsys_state *css,

			     struct cftype *cft)
@@ -7226,7 +7224,7 @@ static struct cftype swap_files[] = { 
	{ }	/* terminate */

};



static struct cftype memsw_cgroup_files[] = {

static struct cftype memsw_files[] = {

	{

		.name = "memsw.usage_in_bytes",

		.private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE),
@@ -7255,13 +7253,12 @@ static struct cftype memsw_cgroup_files[] = { 


static int __init mem_cgroup_swap_init(void)

{

	if (!mem_cgroup_disabled() && really_do_swap_account) {

		do_swap_account = 1;

		WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys,

					       swap_files));

		WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys,

						  memsw_cgroup_files));

	}

	if (mem_cgroup_disabled() || cgroup_memory_noswap)

		return 0;



	WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files));

	WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files));



	return 0;

}

subsys_initcall(mem_cgroup_swap_init);

mm/swap_cgroup.c

+2 −2
Original line number Diff line number Diff line
@@ -171,7 +171,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages) 
	unsigned long length;

	struct swap_cgroup_ctrl *ctrl;



	if (!do_swap_account)

	if (cgroup_memory_noswap)

		return 0;



	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
@@ -209,7 +209,7 @@ void swap_cgroup_swapoff(int type) 
	unsigned long i, length;

	struct swap_cgroup_ctrl *ctrl;



	if (!do_swap_account)

	if (cgroup_memory_noswap)

		return;



	mutex_lock(&swap_cgroup_mutex);

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