Commit 8eb92ed2 authored by Roman Gushchin's avatar Roman Gushchin Committed by Andrew Morton
Browse files

mm: swap_cgroup: allocate swap_cgroup map using vcalloc() 

Currently swap_cgroup's map is constructed as a vmalloc()'s-based array of
pointers to individual struct pages.  This brings an unnecessary
complexity into the code.

This patch turns the swap_cgroup's map into a single space
allocated by vcalloc().

[akpm@linux-foundation.org: s/vfree/kvfree/, per Shakeel]
Link: https://lkml.kernel.org/r/20241115190229.676440-1-roman.gushchin@linux.dev


Signed-off-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Acked-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3472f639

mm/swap_cgroup.c

+13 −70
Original line number Diff line number Diff line
@@ -6,17 +6,18 @@ 
#include <linux/swapops.h> /* depends on mm.h include */



static DEFINE_MUTEX(swap_cgroup_mutex);



struct swap_cgroup {

	unsigned short		id;

};



struct swap_cgroup_ctrl {

	struct page **map;

	unsigned long length;

	struct swap_cgroup *map;

	spinlock_t	lock;

};



static struct swap_cgroup_ctrl swap_cgroup_ctrl[MAX_SWAPFILES];



struct swap_cgroup {

	unsigned short		id;

};

#define SC_PER_PAGE	(PAGE_SIZE/sizeof(struct swap_cgroup))



/*
@@ -33,44 +34,10 @@ struct swap_cgroup { 
 * TODO: we can push these buffers out to HIGHMEM.

 */



/*

 * allocate buffer for swap_cgroup.

 */

static int swap_cgroup_prepare(int type)

{

	struct page *page;

	struct swap_cgroup_ctrl *ctrl;

	unsigned long idx, max;



	ctrl = &swap_cgroup_ctrl[type];



	for (idx = 0; idx < ctrl->length; idx++) {

		page = alloc_page(GFP_KERNEL | __GFP_ZERO);

		if (!page)

			goto not_enough_page;

		ctrl->map[idx] = page;



		if (!(idx % SWAP_CLUSTER_MAX))

			cond_resched();

	}

	return 0;

not_enough_page:

	max = idx;

	for (idx = 0; idx < max; idx++)

		__free_page(ctrl->map[idx]);



	return -ENOMEM;

}



static struct swap_cgroup *__lookup_swap_cgroup(struct swap_cgroup_ctrl *ctrl,

						pgoff_t offset)

{

	struct page *mappage;

	struct swap_cgroup *sc;



	mappage = ctrl->map[offset / SC_PER_PAGE];

	sc = page_address(mappage);

	return sc + offset % SC_PER_PAGE;

	return &ctrl->map[offset];

}



static struct swap_cgroup *lookup_swap_cgroup(swp_entry_t ent,
@@ -168,32 +135,20 @@ unsigned short lookup_swap_cgroup_id(swp_entry_t ent) 


int swap_cgroup_swapon(int type, unsigned long max_pages)

{

	void *array;

	unsigned long length;

	struct swap_cgroup *map;

	struct swap_cgroup_ctrl *ctrl;



	if (mem_cgroup_disabled())

		return 0;



	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);



	array = vcalloc(length, sizeof(void *));

	if (!array)

	map = vcalloc(max_pages, sizeof(struct swap_cgroup));

	if (!map)

		goto nomem;



	ctrl = &swap_cgroup_ctrl[type];

	mutex_lock(&swap_cgroup_mutex);

	ctrl->length = length;

	ctrl->map = array;

	ctrl->map = map;

	spin_lock_init(&ctrl->lock);

	if (swap_cgroup_prepare(type)) {

		/* memory shortage */

		ctrl->map = NULL;

		ctrl->length = 0;

		mutex_unlock(&swap_cgroup_mutex);

		vfree(array);

		goto nomem;

	}

	mutex_unlock(&swap_cgroup_mutex);



	return 0;
@@ -205,8 +160,7 @@ int swap_cgroup_swapon(int type, unsigned long max_pages) 


void swap_cgroup_swapoff(int type)

{

	struct page **map;

	unsigned long i, length;

	struct swap_cgroup *map;

	struct swap_cgroup_ctrl *ctrl;



	if (mem_cgroup_disabled())
@@ -215,19 +169,8 @@ void swap_cgroup_swapoff(int type) 
	mutex_lock(&swap_cgroup_mutex);

	ctrl = &swap_cgroup_ctrl[type];

	map = ctrl->map;

	length = ctrl->length;

	ctrl->map = NULL;

	ctrl->length = 0;

	mutex_unlock(&swap_cgroup_mutex);



	if (map) {

		for (i = 0; i < length; i++) {

			struct page *page = map[i];

			if (page)

				__free_page(page);

			if (!(i % SWAP_CLUSTER_MAX))

				cond_resched();

		}

	vfree(map);

}
 
}