path: root/mm
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authorMinchan Kim <minchan@kernel.org>2014-10-09 15:29:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-10-09 22:26:02 -0400
commit13de8933c96b4557f667c337676f05274e017f83 (patch)
treeeedb527ddfef66108692544e490ff00974c59296 /mm
parentcd2567b6850b1648236a4aab0513a04ebaea6aa8 (diff)
zsmalloc: move pages_allocated to zs_pool
Currently, zram has no feature to limit memory so theoretically zram can deplete system memory. Users have asked for a limit several times as even without exhaustion zram makes it hard to control memory usage of the platform. This patchset adds the feature. Patch 1 makes zs_get_total_size_bytes faster because it would be used frequently in later patches for the new feature. Patch 2 changes zs_get_total_size_bytes's return unit from bytes to page so that zsmalloc doesn't need unnecessary operation(ie, << PAGE_SHIFT). Patch 3 adds new feature. I added the feature into zram layer, not zsmalloc because limiation is zram's requirement, not zsmalloc so any other user using zsmalloc(ie, zpool) shouldn't affected by unnecessary branch of zsmalloc. In future, if every users of zsmalloc want the feature, then, we could move the feature from client side to zsmalloc easily but vice versa would be painful. Patch 4 adds news facility to report maximum memory usage of zram so that this avoids user polling frequently via /sys/block/zram0/ mem_used_total and ensures transient max are not missed. This patch (of 4): pages_allocated has counted in size_class structure and when user of zsmalloc want to see total_size_bytes, it should gather all of count from each size_class to report the sum. It's not bad if user don't see the value often but if user start to see the value frequently, it would be not a good deal for performance pov. This patch moves the count from size_class to zs_pool so it could reduce memory footprint (from [255 * 8byte] to [sizeof(atomic_long_t)]). Signed-off-by: Minchan Kim <minchan@kernel.org> Reviewed-by: Dan Streetman <ddstreet@ieee.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: <juno.choi@lge.com> Cc: <seungho1.park@lge.com> Cc: Luigi Semenzato <semenzato@google.com> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Seth Jennings <sjennings@variantweb.net> Reviewed-by: David Horner <ds2horner@gmail.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
1 files changed, 8 insertions, 15 deletions
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 94f38fac5e81..2a4acf400846 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -199,9 +199,6 @@ struct size_class {
spinlock_t lock;
- /* stats */
- u64 pages_allocated;
struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
@@ -220,6 +217,7 @@ struct zs_pool {
struct size_class size_class[ZS_SIZE_CLASSES];
gfp_t flags; /* allocation flags used when growing pool */
+ atomic_long_t pages_allocated;
@@ -1028,8 +1026,9 @@ unsigned long zs_malloc(struct zs_pool *pool, size_t size)
return 0;
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
+ atomic_long_add(class->pages_per_zspage,
+ &pool->pages_allocated);
- class->pages_allocated += class->pages_per_zspage;
obj = (unsigned long)first_page->freelist;
@@ -1082,14 +1081,13 @@ void zs_free(struct zs_pool *pool, unsigned long obj)
fullness = fix_fullness_group(pool, first_page);
- if (fullness == ZS_EMPTY)
- class->pages_allocated -= class->pages_per_zspage;
- if (fullness == ZS_EMPTY)
+ if (fullness == ZS_EMPTY) {
+ atomic_long_sub(class->pages_per_zspage,
+ &pool->pages_allocated);
+ }
@@ -1185,12 +1183,7 @@ EXPORT_SYMBOL_GPL(zs_unmap_object);
u64 zs_get_total_size_bytes(struct zs_pool *pool)
- int i;
- u64 npages = 0;
- for (i = 0; i < ZS_SIZE_CLASSES; i++)
- npages += pool->size_class[i].pages_allocated;
+ u64 npages = atomic_long_read(&pool->pages_allocated);
return npages << PAGE_SHIFT;

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