mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol

Since 2d1c4980 ("mm: memcontrol: make swap tracking an integral part
of memory control"), CONFIG_MEMCG_SWAP hasn't been a user-visible config
option anymore, it just means CONFIG_MEMCG && CONFIG_SWAP.

Update the sites accordingly and drop the symbol.

[ While touching the docs, remove two references to CONFIG_MEMCG_KMEM,
  which hasn't been a user-visible symbol for over half a decade. ]

Link: https://lkml.kernel.org/r/20220926135704.400818-5-hannes@cmpxchg.orgSigned-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Documentation/admin-guide/cgroup-v1/memory.rst

@@ -299,7 +299,7 @@ Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by
 lruvec->lru_lock; PG_lru bit of page->flags is cleared before
 isolating a page from its LRU under lruvec->lru_lock.
 
-2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM)
+2.7 Kernel Memory Extension
 -----------------------------------------------
 
 With the Kernel memory extension, the Memory Controller is able to limit
@@ -386,8 +386,6 @@ U != 0, K >= U:
 
 a. Enable CONFIG_CGROUPS
 b. Enable CONFIG_MEMCG
-c. Enable CONFIG_MEMCG_SWAP (to use swap extension)
-d. Enable CONFIG_MEMCG_KMEM (to use kmem extension)
 
 3.1. Prepare the cgroups (see cgroups.txt, Why are cgroups needed?)
 -------------------------------------------------------------------

arch/mips/configs/db1xxx_defconfig

@@ -9,7 +9,6 @@ CONFIG_HIGH_RES_TIMERS=y
 CONFIG_LOG_BUF_SHIFT=16
 CONFIG_CGROUPS=y
 CONFIG_MEMCG=y
-CONFIG_MEMCG_SWAP=y
 CONFIG_BLK_CGROUP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_CFS_BANDWIDTH=y

arch/mips/configs/generic_defconfig

@@ -3,7 +3,6 @@ CONFIG_NO_HZ_IDLE=y
 CONFIG_IKCONFIG=y
 CONFIG_IKCONFIG_PROC=y
 CONFIG_MEMCG=y
-CONFIG_MEMCG_SWAP=y
 CONFIG_BLK_CGROUP=y
 CONFIG_CFS_BANDWIDTH=y
 CONFIG_RT_GROUP_SCHED=y

arch/powerpc/configs/powernv_defconfig

@@ -17,7 +17,6 @@ CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
 CONFIG_NUMA_BALANCING=y
 CONFIG_CGROUPS=y
 CONFIG_MEMCG=y
-CONFIG_MEMCG_SWAP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_CGROUP_FREEZER=y
 CONFIG_CPUSETS=y

arch/powerpc/configs/pseries_defconfig

@@ -16,7 +16,6 @@ CONFIG_LOG_CPU_MAX_BUF_SHIFT=13
 CONFIG_NUMA_BALANCING=y
 CONFIG_CGROUPS=y
 CONFIG_MEMCG=y
-CONFIG_MEMCG_SWAP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_CGROUP_FREEZER=y
 CONFIG_CPUSETS=y

arch/sh/configs/sdk7786_defconfig

@@ -16,7 +16,6 @@ CONFIG_CPUSETS=y
 # CONFIG_PROC_PID_CPUSET is not set
 CONFIG_CGROUP_CPUACCT=y
 CONFIG_CGROUP_MEMCG=y
-CONFIG_CGROUP_MEMCG_SWAP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_RT_GROUP_SCHED=y
 CONFIG_BLK_CGROUP=y

arch/sh/configs/urquell_defconfig

@@ -14,7 +14,6 @@ CONFIG_CPUSETS=y
 # CONFIG_PROC_PID_CPUSET is not set
 CONFIG_CGROUP_CPUACCT=y
 CONFIG_CGROUP_MEMCG=y
-CONFIG_CGROUP_MEMCG_SWAP=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_RT_GROUP_SCHED=y
 CONFIG_BLK_DEV_INITRD=y

include/linux/swap.h

@@ -666,7 +666,7 @@ static inline void folio_throttle_swaprate(struct folio *folio, gfp_t gfp)
 	cgroup_throttle_swaprate(&folio->page, gfp);
 }
 
-#ifdef CONFIG_MEMCG_SWAP
+#if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
 void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry);
 int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry);
 static inline int mem_cgroup_try_charge_swap(struct folio *folio,

include/linux/swap_cgroup.h

@@ -4,7 +4,7 @@
 
 #include <linux/swap.h>
 
-#ifdef CONFIG_MEMCG_SWAP
+#if defined(CONFIG_MEMCG) && defined(CONFIG_SWAP)
 
 extern unsigned short swap_cgroup_cmpxchg(swp_entry_t ent,
 					unsigned short old, unsigned short new);
@@ -40,6 +40,6 @@ static inline void swap_cgroup_swapoff(int type)
 	return;
 }
 
-#endif /* CONFIG_MEMCG_SWAP */
+#endif
 
 #endif /* __LINUX_SWAP_CGROUP_H */

init/Kconfig

@@ -958,11 +958,6 @@ config MEMCG
 	help
 	  Provides control over the memory footprint of tasks in a cgroup.
 
-config MEMCG_SWAP
-	bool
-	depends on MEMCG && SWAP
-	default y
-
 config MEMCG_KMEM
 	bool
 	depends on MEMCG && !SLOB

mm/Makefile

@@ -98,7 +98,9 @@ obj-$(CONFIG_DEVICE_MIGRATION) += migrate_device.o
 obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o khugepaged.o
 obj-$(CONFIG_PAGE_COUNTER) += page_counter.o
 obj-$(CONFIG_MEMCG) += memcontrol.o vmpressure.o
-obj-$(CONFIG_MEMCG_SWAP) += swap_cgroup.o
+ifdef CONFIG_SWAP
+obj-$(CONFIG_MEMCG) += swap_cgroup.o
+endif
 obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o
 obj-$(CONFIG_GUP_TEST) += gup_test.o
 obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o

mm/memcontrol.c

@@ -3423,7 +3423,7 @@ void split_page_memcg(struct page *head, unsigned int nr)
 		css_get_many(&memcg->css, nr - 1);
 }
 
-#ifdef CONFIG_MEMCG_SWAP
+#ifdef CONFIG_SWAP
 /**
  * mem_cgroup_move_swap_account - move swap charge and swap_cgroup's record.
  * @entry: swap entry to be moved
@@ -7296,7 +7296,7 @@ static int __init mem_cgroup_init(void)
 }
 subsys_initcall(mem_cgroup_init);
 
-#ifdef CONFIG_MEMCG_SWAP
+#ifdef CONFIG_SWAP
 static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg)
 {
 	while (!refcount_inc_not_zero(&memcg->id.ref)) {
@@ -7788,4 +7788,4 @@ static int __init mem_cgroup_swap_init(void)
 }
 subsys_initcall(mem_cgroup_swap_init);
 
-#endif /* CONFIG_MEMCG_SWAP */
+#endif /* CONFIG_SWAP */

tools/testing/selftests/cgroup/config

@@ -4,5 +4,4 @@ CONFIG_CGROUP_FREEZER=y
 CONFIG_CGROUP_SCHED=y
 CONFIG_MEMCG=y
 CONFIG_MEMCG_KMEM=y
-CONFIG_MEMCG_SWAP=y
 CONFIG_PAGE_COUNTER=y