[PATCH] mm: use unique zsmalloc caches names

[Sergey Senozhatsky <senozhatsky@chromium.org>]

Each zsmalloc pool maintains several named kmem-caches for
zs_handle-s and  zspage-s.  On a system with multiple zsmalloc
pools and CONFIG_DEBUG_VM this triggers kmem_cache_sanity_check():

  kmem_cache of name 'zspage' already exists
  WARNING: at mm/slab_common.c:108 do_kmem_cache_create_usercopy+0xb5/0x310
  ...

  kmem_cache of name 'zs_handle' already exists
  WARNING: at mm/slab_common.c:108 do_kmem_cache_create_usercopy+0xb5/0x310
  ...

We provide zram device name when init its zsmalloc pool, so we can
use that same name for zsmalloc caches and, hence, create unique
names that can easily be linked to zram device that has created
them.

So instead of having this

cat /proc/slabinfo
slabinfo - version: 2.1
zspage                46     46    ...
zs_handle            128    128    ...
zspage             34270  34270    ...
zs_handle          34816  34816    ...
zspage                 0      0    ...
zs_handle              0      0    ...

We now have this

cat /proc/slabinfo
slabinfo - version: 2.1
zspage-zram2          46     46    ...
zs_handle-zram2      128    128    ...
zspage-zram0       34270  34270    ...
zs_handle-zram0    34816  34816    ...
zspage-zram1           0      0    ...
zs_handle-zram1        0      0    ...

Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
 mm/zsmalloc.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 73a3ec5b21ad..896ca02ed75a 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -293,13 +293,17 @@ static void SetZsPageMovable(struct zs_pool *pool, struct zspage *zspage) {}
 
 static int create_cache(struct zs_pool *pool)
 {
-	pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
-					0, 0, NULL);
+	char name[32];
+
+	snprintf(name, sizeof(name), "zs_handle-%s", pool->name);
+	pool->handle_cachep = kmem_cache_create(name, ZS_HANDLE_SIZE,
+						0, 0, NULL);
 	if (!pool->handle_cachep)
 		return 1;
 
-	pool->zspage_cachep = kmem_cache_create("zspage", sizeof(struct zspage),
-					0, 0, NULL);
+	snprintf(name, sizeof(name), "zspage-%s", pool->name);
+	pool->zspage_cachep = kmem_cache_create(name, sizeof(struct zspage),
+						0, 0, NULL);
 	if (!pool->zspage_cachep) {
 		kmem_cache_destroy(pool->handle_cachep);
 		pool->handle_cachep = NULL;
-- 
2.46.0.469.g59c65b2a67-goog