From 2d11085e404f7b45ac4de60db2c9685e349c172d Mon Sep 17 00:00:00 2001 From: Michal Hocko Date: Fri, 22 Feb 2013 16:34:43 -0800 Subject: [PATCH] memcg: do not create memsw files if swap accounting is disabled Zhouping Liu has reported that memsw files are exported even though swap accounting is runtime disabled if MEMCG_SWAP is enabled. This behavior has been introduced by commit af36f906c0f4 ("memcg: always create memsw files if CGROUP_MEM_RES_CTLR_SWAP") and it causes any attempt to open the file to return EOPNOTSUPP. Although EOPNOTSUPP should say be clear that memsw operations are not supported in the given configuration it is fair to say that this behavior could be quite confusing. Let's tear memsw files out of default cgroup files and add them only if the swap accounting is really enabled (either by MEMCG_SWAP_ENABLED or swapaccount=1 boot parameter). We can hook into mem_cgroup_init which is called when the memcg subsystem is initialized and which happens after boot command line is processed. Signed-off-by: Michal Hocko Reported-by: Zhouping Liu Tested-by: Zhouping Liu Cc: Kamezawa Hiroyuki Cc: David Rientjes Cc: Li Zefan Cc: CAI Qian Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 94 ++++++++++++++++++++++++++++--------------------- 1 file changed, 54 insertions(+), 40 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f85861531f22..00ce03e8a277 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5823,33 +5823,6 @@ static struct cftype mem_cgroup_files[] = { .read_seq_string = memcg_numa_stat_show, }, #endif -#ifdef CONFIG_MEMCG_SWAP - { - .name = "memsw.usage_in_bytes", - .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), - .read = mem_cgroup_read, - .register_event = mem_cgroup_usage_register_event, - .unregister_event = mem_cgroup_usage_unregister_event, - }, - { - .name = "memsw.max_usage_in_bytes", - .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), - .trigger = mem_cgroup_reset, - .read = mem_cgroup_read, - }, - { - .name = "memsw.limit_in_bytes", - .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), - .write_string = mem_cgroup_write, - .read = mem_cgroup_read, - }, - { - .name = "memsw.failcnt", - .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), - .trigger = mem_cgroup_reset, - .read = mem_cgroup_read, - }, -#endif #ifdef CONFIG_MEMCG_KMEM { .name = "kmem.limit_in_bytes", @@ -5884,6 +5857,36 @@ static struct cftype mem_cgroup_files[] = { { }, /* terminate */ }; +#ifdef CONFIG_MEMCG_SWAP +static struct cftype memsw_cgroup_files[] = { + { + .name = "memsw.usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), + .read = mem_cgroup_read, + .register_event = mem_cgroup_usage_register_event, + .unregister_event = mem_cgroup_usage_unregister_event, + }, + { + .name = "memsw.max_usage_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_MAX_USAGE), + .trigger = mem_cgroup_reset, + .read = mem_cgroup_read, + }, + { + .name = "memsw.limit_in_bytes", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_LIMIT), + .write_string = mem_cgroup_write, + .read = mem_cgroup_read, + }, + { + .name = "memsw.failcnt", + .private = MEMFILE_PRIVATE(_MEMSWAP, RES_FAILCNT), + .trigger = mem_cgroup_reset, + .read = mem_cgroup_read, + }, + { }, /* terminate */ +}; +#endif static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn; @@ -6783,19 +6786,6 @@ struct cgroup_subsys mem_cgroup_subsys = { .use_id = 1, }; -/* - * The rest of init is performed during ->css_alloc() for root css which - * happens before initcalls. hotcpu_notifier() can't be done together as - * it would introduce circular locking by adding cgroup_lock -> cpu hotplug - * dependency. Do it from a subsys_initcall(). - */ -static int __init mem_cgroup_init(void) -{ - hotcpu_notifier(memcg_cpu_hotplug_callback, 0); - return 0; -} -subsys_initcall(mem_cgroup_init); - #ifdef CONFIG_MEMCG_SWAP static int __init enable_swap_account(char *s) { @@ -6808,4 +6798,28 @@ static int __init enable_swap_account(char *s) } __setup("swapaccount=", enable_swap_account); +static void __init memsw_file_init(void) +{ + if (really_do_swap_account) + WARN_ON(cgroup_add_cftypes(&mem_cgroup_subsys, + memsw_cgroup_files)); +} +#else +static void __init memsw_file_init(void) +{ +} #endif + +/* + * The rest of init is performed during ->css_alloc() for root css which + * happens before initcalls. hotcpu_notifier() can't be done together as + * it would introduce circular locking by adding cgroup_lock -> cpu hotplug + * dependency. Do it from a subsys_initcall(). + */ +static int __init mem_cgroup_init(void) +{ + hotcpu_notifier(memcg_cpu_hotplug_callback, 0); + memsw_file_init(); + return 0; +} +subsys_initcall(mem_cgroup_init); -- 2.20.1