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Message-ID: <20241115190229.676440-1-roman.gushchin@linux.dev>
Date: Fri, 15 Nov 2024 19:02:28 +0000
From: Roman Gushchin <roman.gushchin@...ux.dev>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org,
linux-mm@...ck.org,
Shakeel Butt <shakeel.butt@...ux.dev>,
Michal Hocko <mhocko@...nel.org>,
Johannes Weiner <hannes@...xchg.org>,
Roman Gushchin <roman.gushchin@...ux.dev>
Subject: [PATCH 1/2] 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().
Signed-off-by: Roman Gushchin <roman.gushchin@...ux.dev>
---
mm/swap_cgroup.c | 83 ++++++++----------------------------------------
1 file changed, 13 insertions(+), 70 deletions(-)
diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index da1278f0563b..18de498c84a4 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -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);
- }
+ kvfree(map);
}
--
2.47.0.338.g60cca15819-goog
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