path: root/init
diff options
authorTejun Heo <>2017-02-22 15:41:39 -0800
committerLinus Torvalds <>2017-02-22 16:41:27 -0800
commit1663f26df3df7df3720306ca67f5ea8296d68fa1 (patch)
tree6ad80b7ccc7d093c0a14532affa376452f523afe /init
parent17cc4dfeda97636d67e83de8cd41940b65a93bc7 (diff)
slub: make sysfs directories for memcg sub-caches optional
SLUB creates a per-cache directory under /sys/kernel/slab which hosts a bunch of debug files. Usually, there aren't that many caches on a system and this doesn't really matter; however, if memcg is in use, each cache can have per-cgroup sub-caches. SLUB creates the same directories for these sub-caches under /sys/kernel/slab/$CACHE/cgroup. Unfortunately, because there can be a lot of cgroups, active or draining, the product of the numbers of caches, cgroups and files in each directory can reach a very high number - hundreds of thousands is commonplace. Millions and beyond aren't difficult to reach either. What's under /sys/kernel/slab is primarily for debugging and the information and control on the a root cache already cover its sub-caches. While having a separate directory for each sub-cache can be helpful for development, it doesn't make much sense to pay this amount of overhead by default. This patch introduces a boot parameter slub_memcg_sysfs which determines whether to create sysfs directories for per-memcg sub-caches. It also adds CONFIG_SLUB_MEMCG_SYSFS_ON which determines the boot parameter's default value and defaults to 0. [ kset_unregister(NULL) is legal] Link: Signed-off-by: Tejun Heo <> Cc: Christoph Lameter <> Cc: Pekka Enberg <> Cc: David Rientjes <> Cc: Joonsoo Kim <> Cc: Vladimir Davydov <> Cc: Michal Hocko <> Cc: Johannes Weiner <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'init')
1 files changed, 14 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index 55bb6fb..22f437f 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1779,6 +1779,20 @@ config SLUB_DEBUG
SLUB sysfs support. /sys/slab will not exist and there will be
no support for cache validation etc.
+ default n
+ bool "Enable memcg SLUB sysfs support by default" if EXPERT
+ depends on SLUB && SYSFS && MEMCG
+ help
+ SLUB creates a directory under /sys/kernel/slab for each
+ allocation cache to host info and debug files. If memory
+ cgroup is enabled, each cache can have per memory cgroup
+ caches. SLUB can create the same sysfs directories for these
+ caches under /sys/kernel/slab/CACHE/cgroup but it can lead
+ to a very high number of debug files being created. This is
+ controlled by slub_memcg_sysfs boot parameter and this
+ config option determines the parameter's default value.
bool "Disable heap randomization"
default y