From: Balbir Singh A boot option for the memory controller was discussed on lkml. It is a good idea to add it, since it saves memory for people who want to turn off the memory controller. By default the option is on for the following two reasons: 1. It provides compatibility with the current scheme where the memory controller turns on if the config option is enabled 2. It allows for wider testing of the memory controller, once the config option is enabled We still allow the create, destroy callbacks to succeed, since they are not aware of boot options. We do not populate the directory will memory resource controller specific files. Signed-off-by: Balbir Singh Cc: Paul Menage Cc: Balbir Singh Cc: Pavel Emelyanov Cc: KAMEZAWA Hiroyuki Cc: Hugh Dickins Cc: Sudhir Kumar Cc: YAMAMOTO Takashi Cc: David Rientjes Signed-off-by: Andrew Morton --- mm/memcontrol.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff -puN mm/memcontrol.c~memory-controller-make-memory-resource-control-aware-of-boot-options mm/memcontrol.c --- a/mm/memcontrol.c~memory-controller-make-memory-resource-control-aware-of-boot-options +++ a/mm/memcontrol.c @@ -533,6 +533,9 @@ static int mem_cgroup_charge_common(stru unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES; struct mem_cgroup_per_zone *mz; + if (mem_cgroup_subsys.disabled) + return 0; + /* * Should page_cgroup's go to their own slab? * One could optimize the performance of the charging routine @@ -665,6 +668,9 @@ void mem_cgroup_uncharge_page(struct pag struct mem_cgroup_per_zone *mz; unsigned long flags; + if (mem_cgroup_subsys.disabled) + return; + /* * Check if our page_cgroup is valid */ @@ -705,6 +711,9 @@ int mem_cgroup_prepare_migration(struct { struct page_cgroup *pc; + if (mem_cgroup_subsys.disabled) + return 0; + lock_page_cgroup(page); pc = page_get_page_cgroup(page); if (pc) @@ -803,6 +812,9 @@ static int mem_cgroup_force_empty(struct int ret = -EBUSY; int node, zid; + if (mem_cgroup_subsys.disabled) + return 0; + css_get(&mem->css); /* * page reclaim code (kswapd etc..) will move pages between @@ -1022,6 +1034,8 @@ static void mem_cgroup_destroy(struct cg static int mem_cgroup_populate(struct cgroup_subsys *ss, struct cgroup *cont) { + if (mem_cgroup_subsys.disabled) + return 0; return cgroup_add_files(cont, ss, mem_cgroup_files, ARRAY_SIZE(mem_cgroup_files)); } @@ -1034,6 +1048,9 @@ static void mem_cgroup_move_task(struct struct mm_struct *mm; struct mem_cgroup *mem, *old_mem; + if (mem_cgroup_subsys.disabled) + return; + mm = get_task_mm(p); if (mm == NULL) return; _