From: Johannes Weiner <hannes@xxxxxxxxxxx> Subject: mm: memcontrol: prepare swap controller setup for integration A few cleanups to streamline the swap controller setup: - Replace the do_swap_account flag with cgroup_memory_noswap. This brings it in line with other functionality that is usually available unless explicitly opted out of - nosocket, nokmem. - Remove the really_do_swap_account flag that stores the boot option and is later used to switch the do_swap_account. It's not clear why this indirection is/was necessary. Use do_swap_account directly. - Minor coding style polishing Link: http://lkml.kernel.org/r/20200508183105.225460-15-hannes@xxxxxxxxxxx Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reviewed-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Roman Gushchin <guro@xxxxxx> Cc: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Balbir Singh <bsingharora@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/memcontrol.h | 2 - mm/memcontrol.c | 59 ++++++++++++++++------------------- mm/swap_cgroup.c | 4 +- 3 files changed, 31 insertions(+), 34 deletions(-) --- a/include/linux/memcontrol.h~mm-memcontrol-prepare-swap-controller-setup-for-integration +++ a/include/linux/memcontrol.h @@ -558,7 +558,7 @@ struct mem_cgroup *mem_cgroup_get_oom_gr void mem_cgroup_print_oom_group(struct mem_cgroup *memcg); #ifdef CONFIG_MEMCG_SWAP -extern int do_swap_account; +extern bool cgroup_memory_noswap; #endif struct mem_cgroup *lock_page_memcg(struct page *page); --- a/mm/memcontrol.c~mm-memcontrol-prepare-swap-controller-setup-for-integration +++ a/mm/memcontrol.c @@ -83,10 +83,14 @@ static bool cgroup_memory_nokmem; /* Whether the swap controller is active */ #ifdef CONFIG_MEMCG_SWAP -int do_swap_account __read_mostly; +#ifdef CONFIG_MEMCG_SWAP_ENABLED +bool cgroup_memory_noswap __read_mostly; #else -#define do_swap_account 0 -#endif +bool cgroup_memory_noswap __read_mostly = 1; +#endif /* CONFIG_MEMCG_SWAP_ENABLED */ +#else +#define cgroup_memory_noswap 1 +#endif /* CONFIG_MEMCG_SWAP */ #ifdef CONFIG_CGROUP_WRITEBACK static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq); @@ -95,7 +99,7 @@ static DECLARE_WAIT_QUEUE_HEAD(memcg_cgw /* Whether legacy memory+swap accounting is active */ static bool do_memsw_account(void) { - return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && do_swap_account; + return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && !cgroup_memory_noswap; } #define THRESHOLDS_EVENTS_TARGET 128 @@ -6528,18 +6532,19 @@ int mem_cgroup_charge(struct page *page, /* * Every swap fault against a single page tries to charge the * page, bail as early as possible. shmem_unuse() encounters - * already charged pages, too. The USED bit is protected by - * the page lock, which serializes swap cache removal, which + * already charged pages, too. page->mem_cgroup is protected + * by the page lock, which serializes swap cache removal, which * in turn serializes uncharging. */ VM_BUG_ON_PAGE(!PageLocked(page), page); if (compound_head(page)->mem_cgroup) goto out; - if (do_swap_account) { + if (!cgroup_memory_noswap) { swp_entry_t ent = { .val = page_private(page), }; - unsigned short id = lookup_swap_cgroup_id(ent); + unsigned short id; + id = lookup_swap_cgroup_id(ent); rcu_read_lock(); memcg = mem_cgroup_from_id(id); if (memcg && !css_tryget_online(&memcg->css)) @@ -7012,7 +7017,7 @@ int mem_cgroup_try_charge_swap(struct pa struct mem_cgroup *memcg; unsigned short oldid; - if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || !do_swap_account) + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys) || cgroup_memory_noswap) return 0; memcg = page->mem_cgroup; @@ -7056,7 +7061,7 @@ void mem_cgroup_uncharge_swap(swp_entry_ struct mem_cgroup *memcg; unsigned short id; - if (!do_swap_account) + if (cgroup_memory_noswap) return; id = swap_cgroup_record(entry, 0, nr_pages); @@ -7079,7 +7084,7 @@ long mem_cgroup_get_nr_swap_pages(struct { long nr_swap_pages = get_nr_swap_pages(); - if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) + if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) return nr_swap_pages; for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg)) nr_swap_pages = min_t(long, nr_swap_pages, @@ -7096,7 +7101,7 @@ bool mem_cgroup_swap_full(struct page *p if (vm_swap_full()) return true; - if (!do_swap_account || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) + if (cgroup_memory_noswap || !cgroup_subsys_on_dfl(memory_cgrp_subsys)) return false; memcg = page->mem_cgroup; @@ -7114,22 +7119,15 @@ bool mem_cgroup_swap_full(struct page *p return false; } -/* for remember boot option*/ -#ifdef CONFIG_MEMCG_SWAP_ENABLED -static int really_do_swap_account __initdata = 1; -#else -static int really_do_swap_account __initdata; -#endif - -static int __init enable_swap_account(char *s) +static int __init setup_swap_account(char *s) { if (!strcmp(s, "1")) - really_do_swap_account = 1; + cgroup_memory_noswap = 0; else if (!strcmp(s, "0")) - really_do_swap_account = 0; + cgroup_memory_noswap = 1; return 1; } -__setup("swapaccount=", enable_swap_account); +__setup("swapaccount=", setup_swap_account); static u64 swap_current_read(struct cgroup_subsys_state *css, struct cftype *cft) @@ -7226,7 +7224,7 @@ static struct cftype swap_files[] = { { } /* terminate */ }; -static struct cftype memsw_cgroup_files[] = { +static struct cftype memsw_files[] = { { .name = "memsw.usage_in_bytes", .private = MEMFILE_PRIVATE(_MEMSWAP, RES_USAGE), @@ -7255,13 +7253,12 @@ static struct cftype memsw_cgroup_files[ static int __init mem_cgroup_swap_init(void) { - if (!mem_cgroup_disabled() && really_do_swap_account) { - do_swap_account = 1; - WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, - swap_files)); - WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, - memsw_cgroup_files)); - } + if (mem_cgroup_disabled() || cgroup_memory_noswap) + return 0; + + WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files)); + WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files)); + return 0; } subsys_initcall(mem_cgroup_swap_init); --- a/mm/swap_cgroup.c~mm-memcontrol-prepare-swap-controller-setup-for-integration +++ a/mm/swap_cgroup.c @@ -171,7 +171,7 @@ int swap_cgroup_swapon(int type, unsigne unsigned long length; struct swap_cgroup_ctrl *ctrl; - if (!do_swap_account) + if (cgroup_memory_noswap) return 0; length = DIV_ROUND_UP(max_pages, SC_PER_PAGE); @@ -209,7 +209,7 @@ void swap_cgroup_swapoff(int type) unsigned long i, length; struct swap_cgroup_ctrl *ctrl; - if (!do_swap_account) + if (cgroup_memory_noswap) return; mutex_lock(&swap_cgroup_mutex); _
