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* [PATCH 0/4] memcg swap fix & cleanups
@ 2022-09-26 13:57 Johannes Weiner
  2022-09-26 13:57 ` [PATCH 1/4] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Johannes Weiner
                   ` (3 more replies)
  0 siblings, 4 replies; 7+ messages in thread
From: Johannes Weiner @ 2022-09-26 13:57 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Shakeel Butt, Michal Hocko, Roman Gushchin, Hugh Dickins,
	linux-mm, cgroups, linux-kernel

This is a refresh of older patches that fell through the cracks.

Applies on top of mm-unstable.

 Documentation/admin-guide/cgroup-v1/memory.rst  |  4 +-
 Documentation/admin-guide/kernel-parameters.txt |  6 --
 arch/mips/configs/db1xxx_defconfig              |  1 -
 arch/mips/configs/generic_defconfig             |  1 -
 arch/powerpc/configs/powernv_defconfig          |  1 -
 arch/powerpc/configs/pseries_defconfig          |  1 -
 arch/sh/configs/sdk7786_defconfig               |  1 -
 arch/sh/configs/urquell_defconfig               |  1 -
 include/linux/swap.h                            |  2 +-
 include/linux/swap_cgroup.h                     |  4 +-
 init/Kconfig                                    |  5 --
 mm/Makefile                                     |  4 +-
 mm/memcontrol.c                                 | 79 ++++++++---------------
 mm/swap_cgroup.c                                |  6 ++
 tools/testing/selftests/cgroup/config           |  1 -
 15 files changed, 39 insertions(+), 78 deletions(-)




^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH 1/4] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
  2022-09-26 13:57 [PATCH 0/4] memcg swap fix & cleanups Johannes Weiner
@ 2022-09-26 13:57 ` Johannes Weiner
  2022-09-26 13:57 ` [PATCH 2/4] mm: memcontrol: deprecate swapaccounting=0 mode Johannes Weiner
                   ` (2 subsequent siblings)
  3 siblings, 0 replies; 7+ messages in thread
From: Johannes Weiner @ 2022-09-26 13:57 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Shakeel Butt, Michal Hocko, Roman Gushchin, Hugh Dickins,
	linux-mm, cgroups, linux-kernel

Since commit 2d1c498072de ("mm: memcontrol: make swap tracking an
integral part of memory control"), the cgroup swap arrays are used to
track memory ownership at the time of swap readahead and swapoff, even
if swap space *accounting* has been turned off by the user via
swapaccount=0 (which sets cgroup_memory_noswap).

However, the patch was overzealous: by simply dropping the
cgroup_memory_noswap conditionals in the swapon, swapoff and uncharge
path, it caused the cgroup arrays being allocated even when the memory
controller as a whole is disabled. This is a waste of that memory.

Restore mem_cgroup_disabled() checks, implied previously by
cgroup_memory_noswap, in the swapon, swapoff, and swap_entry_free
callbacks.

Fixes: 2d1c498072de ("mm: memcontrol: make swap tracking an integral part of memory control")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
---
 mm/memcontrol.c  | 3 +++
 mm/swap_cgroup.c | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6b74bbdc2659..9e3c010ca676 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -7459,6 +7459,9 @@ void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 	struct mem_cgroup *memcg;
 	unsigned short id;
 
+	if (mem_cgroup_disabled())
+		return;
+
 	id = swap_cgroup_record(entry, 0, nr_pages);
 	rcu_read_lock();
 	memcg = mem_cgroup_from_id(id);
diff --git a/mm/swap_cgroup.c b/mm/swap_cgroup.c
index 5a9442979a18..db6c4a26cf59 100644
--- a/mm/swap_cgroup.c
+++ b/mm/swap_cgroup.c
@@ -170,6 +170,9 @@ int swap_cgroup_swapon(int type, unsigned long max_pages)
 	unsigned long length;
 	struct swap_cgroup_ctrl *ctrl;
 
+	if (mem_cgroup_disabled())
+		return 0;
+
 	length = DIV_ROUND_UP(max_pages, SC_PER_PAGE);
 
 	array = vcalloc(length, sizeof(void *));
@@ -204,6 +207,9 @@ void swap_cgroup_swapoff(int type)
 	unsigned long i, length;
 	struct swap_cgroup_ctrl *ctrl;
 
+	if (mem_cgroup_disabled())
+		return;
+
 	mutex_lock(&swap_cgroup_mutex);
 	ctrl = &swap_cgroup_ctrl[type];
 	map = ctrl->map;
-- 
2.37.3



^ permalink raw reply related	[flat|nested] 7+ messages in thread
* [PATCH 2/4] mm: memcontrol: deprecate swapaccounting=0 mode
  2022-09-26 13:57 [PATCH 0/4] memcg swap fix & cleanups Johannes Weiner
  2022-09-26 13:57 ` [PATCH 1/4] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Johannes Weiner
@ 2022-09-26 13:57 ` Johannes Weiner
  2022-09-26 13:57 ` [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places Johannes Weiner
  2022-09-26 13:57 ` [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol Johannes Weiner
  3 siblings, 0 replies; 7+ messages in thread
From: Johannes Weiner @ 2022-09-26 13:57 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Shakeel Butt, Michal Hocko, Roman Gushchin, Hugh Dickins,
	linux-mm, cgroups, linux-kernel

The swapaccounting= commandline option already does very little
today. To close a trivial containment failure case, the swap ownership
tracking part of the swap controller has recently become mandatory
(see commit 2d1c498072de ("mm: memcontrol: make swap tracking an
integral part of memory control") for details), which makes up the
majority of the work during swapout, swapin, and the swap slot map.

The only thing left under this flag is the page_counter operations and
the visibility of the swap control files in the first place, which are
rather meager savings. There also aren't many scenarios, if any, where
controlling the memory of a cgroup while allowing it unlimited access
to a global swap space is a workable resource isolation strategy.

On the other hand, there have been several bugs and confusion around
the many possible swap controller states (cgroup1 vs cgroup2 behavior,
memory accounting without swap accounting, memcg runtime disabled).

This puts the maintenance overhead of retaining the toggle above its
practical benefits. Deprecate it.

Suggested-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
 .../admin-guide/kernel-parameters.txt         |  6 ---
 mm/memcontrol.c                               | 50 ++++---------------
 2 files changed, 10 insertions(+), 46 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3b95f65bafe2..99a13f2be2ef 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6036,12 +6036,6 @@
 			This parameter controls use of the Protected
 			Execution Facility on pSeries.
 
-	swapaccount=	[KNL]
-			Format: [0|1]
-			Enable accounting of swap in memory resource
-			controller if no parameter or 1 is given or disable
-			it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst)
-
 	swiotlb=	[ARM,IA-64,PPC,MIPS,X86]
 			Format: { <int> [,<int>] | force | noforce }
 			<int> -- Number of I/O TLB slabs
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 9e3c010ca676..4be1b48b9659 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -88,22 +88,6 @@ static bool cgroup_memory_nosocket __ro_after_init;
 /* Kernel memory accounting disabled? */
 static bool cgroup_memory_nokmem __ro_after_init;
 
-/* Whether the swap controller is active */
-#ifdef CONFIG_MEMCG_SWAP
-static bool cgroup_memory_noswap __initdata;
-
-static DEFINE_STATIC_KEY_FALSE(memcg_swap_enabled_key);
-static inline bool memcg_swap_enabled(void)
-{
-	return static_branch_likely(&memcg_swap_enabled_key);
-}
-#else
-static inline bool memcg_swap_enabled(void)
-{
-	return false;
-}
-#endif
-
 #ifdef CONFIG_CGROUP_WRITEBACK
 static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
 #endif
@@ -111,7 +95,7 @@ static DECLARE_WAIT_QUEUE_HEAD(memcg_cgwb_frn_waitq);
 /* Whether legacy memory+swap accounting is active */
 static bool do_memsw_account(void)
 {
-	return !cgroup_subsys_on_dfl(memory_cgrp_subsys) && memcg_swap_enabled();
+	return !cgroup_subsys_on_dfl(memory_cgrp_subsys);
 }
 
 #define THRESHOLDS_EVENTS_TARGET 128
@@ -7379,7 +7363,7 @@ void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
 	if (!mem_cgroup_is_root(memcg))
 		page_counter_uncharge(&memcg->memory, nr_entries);
 
-	if (memcg_swap_enabled() && memcg != swap_memcg) {
+	if (memcg != swap_memcg) {
 		if (!mem_cgroup_is_root(swap_memcg))
 			page_counter_charge(&swap_memcg->memsw, nr_entries);
 		page_counter_uncharge(&memcg->memsw, nr_entries);
@@ -7431,7 +7415,7 @@ int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry)
 
 	memcg = mem_cgroup_id_get_online(memcg);
 
-	if (memcg_swap_enabled() && !mem_cgroup_is_root(memcg) &&
+	if (!mem_cgroup_is_root(memcg) &&
 	    !page_counter_try_charge(&memcg->swap, nr_pages, &counter)) {
 		memcg_memory_event(memcg, MEMCG_SWAP_MAX);
 		memcg_memory_event(memcg, MEMCG_SWAP_FAIL);
@@ -7466,7 +7450,7 @@ void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 	rcu_read_lock();
 	memcg = mem_cgroup_from_id(id);
 	if (memcg) {
-		if (memcg_swap_enabled() && !mem_cgroup_is_root(memcg)) {
+		if (!mem_cgroup_is_root(memcg)) {
 			if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
 				page_counter_uncharge(&memcg->swap, nr_pages);
 			else
@@ -7482,7 +7466,7 @@ long mem_cgroup_get_nr_swap_pages(struct mem_cgroup *memcg)
 {
 	long nr_swap_pages = get_nr_swap_pages();
 
-	if (!memcg_swap_enabled() || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+	if (mem_cgroup_disabled() || do_memsw_account())
 		return nr_swap_pages;
 	for (; memcg != root_mem_cgroup; memcg = parent_mem_cgroup(memcg))
 		nr_swap_pages = min_t(long, nr_swap_pages,
@@ -7499,7 +7483,7 @@ bool mem_cgroup_swap_full(struct folio *folio)
 
 	if (vm_swap_full())
 		return true;
-	if (!memcg_swap_enabled() || !cgroup_subsys_on_dfl(memory_cgrp_subsys))
+	if (do_memsw_account())
 		return false;
 
 	memcg = folio_memcg(folio);
@@ -7519,10 +7503,9 @@ bool mem_cgroup_swap_full(struct folio *folio)
 
 static int __init setup_swap_account(char *s)
 {
-	bool res;
-
-	if (!kstrtobool(s, &res))
-		cgroup_memory_noswap = !res;
+	pr_warn_once("The swapaccount= commandline option is deprecated. "
+		     "Please report your usecase to linux-mm@kvack.org if you "
+		     "depend on this functionality.\n");
 	return 1;
 }
 __setup("swapaccount=", setup_swap_account);
@@ -7791,24 +7774,11 @@ static struct cftype zswap_files[] = {
 };
 #endif /* CONFIG_MEMCG_KMEM && CONFIG_ZSWAP */
 
-/*
- * If mem_cgroup_swap_init() is implemented as a subsys_initcall()
- * instead of a core_initcall(), this could mean cgroup_memory_noswap still
- * remains set to false even when memcg is disabled via "cgroup_disable=memory"
- * boot parameter. This may result in premature OOPS inside
- * mem_cgroup_get_nr_swap_pages() function in corner cases.
- */
 static int __init mem_cgroup_swap_init(void)
 {
-	/* No memory control -> no swap control */
 	if (mem_cgroup_disabled())
-		cgroup_memory_noswap = true;
-
-	if (cgroup_memory_noswap)
 		return 0;
 
-	static_branch_enable(&memcg_swap_enabled_key);
-
 	WARN_ON(cgroup_add_dfl_cftypes(&memory_cgrp_subsys, swap_files));
 	WARN_ON(cgroup_add_legacy_cftypes(&memory_cgrp_subsys, memsw_files));
 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_ZSWAP)
@@ -7816,6 +7786,6 @@ static int __init mem_cgroup_swap_init(void)
 #endif
 	return 0;
 }
-core_initcall(mem_cgroup_swap_init);
+subsys_initcall(mem_cgroup_swap_init);
 
 #endif /* CONFIG_MEMCG_SWAP */
-- 
2.37.3



^ permalink raw reply related	[flat|nested] 7+ messages in thread
* [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places
  2022-09-26 13:57 [PATCH 0/4] memcg swap fix & cleanups Johannes Weiner
  2022-09-26 13:57 ` [PATCH 1/4] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Johannes Weiner
  2022-09-26 13:57 ` [PATCH 2/4] mm: memcontrol: deprecate swapaccounting=0 mode Johannes Weiner
@ 2022-09-26 13:57 ` Johannes Weiner
  2022-09-26 15:20   ` Shakeel Butt
  2022-09-26 13:57 ` [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol Johannes Weiner
  3 siblings, 1 reply; 7+ messages in thread
From: Johannes Weiner @ 2022-09-26 13:57 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Shakeel Butt, Michal Hocko, Roman Gushchin, Hugh Dickins,
	linux-mm, cgroups, linux-kernel

It's slightly more descriptive and consistent with other places that
distinguish cgroup1's combined memory+swap accounting scheme from
cgroup2's dedicated swap accounting.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 mm/memcontrol.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4be1b48b9659..76bb0a18a2f3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1667,17 +1667,17 @@ unsigned long mem_cgroup_get_max(struct mem_cgroup *memcg)
 {
 	unsigned long max = READ_ONCE(memcg->memory.max);
 
-	if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) {
-		if (mem_cgroup_swappiness(memcg))
-			max += min(READ_ONCE(memcg->swap.max),
-				   (unsigned long)total_swap_pages);
-	} else { /* v1 */
+	if (do_memsw_account()) {
 		if (mem_cgroup_swappiness(memcg)) {
 			/* Calculate swap excess capacity from memsw limit */
 			unsigned long swap = READ_ONCE(memcg->memsw.max) - max;
 
 			max += min(swap, (unsigned long)total_swap_pages);
 		}
+	} else {
+		if (mem_cgroup_swappiness(memcg))
+			max += min(READ_ONCE(memcg->swap.max),
+				   (unsigned long)total_swap_pages);
 	}
 	return max;
 }
@@ -7334,7 +7334,7 @@ void mem_cgroup_swapout(struct folio *folio, swp_entry_t entry)
 	if (mem_cgroup_disabled())
 		return;
 
-	if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
+	if (!do_memsw_account())
 		return;
 
 	memcg = folio_memcg(folio);
@@ -7399,7 +7399,7 @@ int __mem_cgroup_try_charge_swap(struct folio *folio, swp_entry_t entry)
 	struct mem_cgroup *memcg;
 	unsigned short oldid;
 
-	if (!cgroup_subsys_on_dfl(memory_cgrp_subsys))
+	if (do_memsw_account())
 		return 0;
 
 	memcg = folio_memcg(folio);
@@ -7451,10 +7451,10 @@ void __mem_cgroup_uncharge_swap(swp_entry_t entry, unsigned int nr_pages)
 	memcg = mem_cgroup_from_id(id);
 	if (memcg) {
 		if (!mem_cgroup_is_root(memcg)) {
-			if (cgroup_subsys_on_dfl(memory_cgrp_subsys))
-				page_counter_uncharge(&memcg->swap, nr_pages);
-			else
+			if (do_memsw_account())
 				page_counter_uncharge(&memcg->memsw, nr_pages);
+			else
+				page_counter_uncharge(&memcg->swap, nr_pages);
 		}
 		mod_memcg_state(memcg, MEMCG_SWAP, -nr_pages);
 		mem_cgroup_id_put_many(memcg, nr_pages);
-- 
2.37.3



^ permalink raw reply related	[flat|nested] 7+ messages in thread
* [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
  2022-09-26 13:57 [PATCH 0/4] memcg swap fix & cleanups Johannes Weiner
                   ` (2 preceding siblings ...)
  2022-09-26 13:57 ` [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places Johannes Weiner
@ 2022-09-26 13:57 ` Johannes Weiner
  2022-09-26 15:22   ` Shakeel Butt
  3 siblings, 1 reply; 7+ messages in thread
From: Johannes Weiner @ 2022-09-26 13:57 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Shakeel Butt, Michal Hocko, Roman Gushchin, Hugh Dickins,
	linux-mm, cgroups, linux-kernel

Since 2d1c498072de ("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. ]

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
 Documentation/admin-guide/cgroup-v1/memory.rst | 4 +---
 arch/mips/configs/db1xxx_defconfig             | 1 -
 arch/mips/configs/generic_defconfig            | 1 -
 arch/powerpc/configs/powernv_defconfig         | 1 -
 arch/powerpc/configs/pseries_defconfig         | 1 -
 arch/sh/configs/sdk7786_defconfig              | 1 -
 arch/sh/configs/urquell_defconfig              | 1 -
 include/linux/swap.h                           | 2 +-
 include/linux/swap_cgroup.h                    | 4 ++--
 init/Kconfig                                   | 5 -----
 mm/Makefile                                    | 4 +++-
 mm/memcontrol.c                                | 6 +++---
 tools/testing/selftests/cgroup/config          | 1 -
 13 files changed, 10 insertions(+), 22 deletions(-)

diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst
index 2cc502a75ef6..5b86245450bd 100644
--- a/Documentation/admin-guide/cgroup-v1/memory.rst
+++ b/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 @@ limit, and "K" the kernel limit. There are three possible ways limits can be
 
 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?)
 -------------------------------------------------------------------
diff --git a/arch/mips/configs/db1xxx_defconfig b/arch/mips/configs/db1xxx_defconfig
index b8bd66300996..83cbdecb27e6 100644
--- a/arch/mips/configs/db1xxx_defconfig
+++ b/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
diff --git a/arch/mips/configs/generic_defconfig b/arch/mips/configs/generic_defconfig
index 714169e411cf..48e4e251779b 100644
--- a/arch/mips/configs/generic_defconfig
+++ b/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
diff --git a/arch/powerpc/configs/powernv_defconfig b/arch/powerpc/configs/powernv_defconfig
index 49f49c263935..4acca5263404 100644
--- a/arch/powerpc/configs/powernv_defconfig
+++ b/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
diff --git a/arch/powerpc/configs/pseries_defconfig b/arch/powerpc/configs/pseries_defconfig
index b571d084c148..fead14ebb1fc 100644
--- a/arch/powerpc/configs/pseries_defconfig
+++ b/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
diff --git a/arch/sh/configs/sdk7786_defconfig b/arch/sh/configs/sdk7786_defconfig
index a8662b6927ec..97b7356639ed 100644
--- a/arch/sh/configs/sdk7786_defconfig
+++ b/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
diff --git a/arch/sh/configs/urquell_defconfig b/arch/sh/configs/urquell_defconfig
index cb2f56468fe0..be478f3148f2 100644
--- a/arch/sh/configs/urquell_defconfig
+++ b/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
diff --git a/include/linux/swap.h b/include/linux/swap.h
index fc8d98660326..a18cf4b7c724 100644
--- a/include/linux/swap.h
+++ b/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,
diff --git a/include/linux/swap_cgroup.h b/include/linux/swap_cgroup.h
index a12dd1c3966c..ae73a87775b3 100644
--- a/include/linux/swap_cgroup.h
+++ b/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 */
diff --git a/init/Kconfig b/init/Kconfig
index 532362fcfe31..7d86cf6b3012 100644
--- a/init/Kconfig
+++ b/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
diff --git a/mm/Makefile b/mm/Makefile
index cc23b0052584..8e105e5b3e29 100644
--- a/mm/Makefile
+++ b/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
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 76bb0a18a2f3..61e05fc281fb 100644
--- a/mm/memcontrol.c
+++ b/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 */
diff --git a/tools/testing/selftests/cgroup/config b/tools/testing/selftests/cgroup/config
index 84fe884fad86..97d549ee894f 100644
--- a/tools/testing/selftests/cgroup/config
+++ b/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
-- 
2.37.3



^ permalink raw reply related	[flat|nested] 7+ messages in thread
* Re: [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places
  2022-09-26 13:57 ` [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places Johannes Weiner
@ 2022-09-26 15:20   ` Shakeel Butt
  0 siblings, 0 replies; 7+ messages in thread
From: Shakeel Butt @ 2022-09-26 15:20 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Andrew Morton, Michal Hocko, Roman Gushchin, Hugh Dickins,
	Linux MM, Cgroups, LKML

On Mon, Sep 26, 2022 at 6:57 AM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> It's slightly more descriptive and consistent with other places that
> distinguish cgroup1's combined memory+swap accounting scheme from
> cgroup2's dedicated swap accounting.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Shakeel Butt <shakeelb@google.com>


^ permalink raw reply	[flat|nested] 7+ messages in thread
* Re: [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
  2022-09-26 13:57 ` [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol Johannes Weiner
@ 2022-09-26 15:22   ` Shakeel Butt
  0 siblings, 0 replies; 7+ messages in thread
From: Shakeel Butt @ 2022-09-26 15:22 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Andrew Morton, Michal Hocko, Roman Gushchin, Hugh Dickins,
	Linux MM, Cgroups, LKML

On Mon, Sep 26, 2022 at 6:57 AM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> Since 2d1c498072de ("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. ]
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

Acked-by: Shakeel Butt <shakeelb@google.com>


^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-09-26 15:22 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-09-26 13:57 [PATCH 0/4] memcg swap fix & cleanups Johannes Weiner
2022-09-26 13:57 ` [PATCH 1/4] mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled Johannes Weiner
2022-09-26 13:57 ` [PATCH 2/4] mm: memcontrol: deprecate swapaccounting=0 mode Johannes Weiner
2022-09-26 13:57 ` [PATCH 3/4] mm: memcontrol: use do_memsw_account() in a few more places Johannes Weiner
2022-09-26 15:20   ` Shakeel Butt
2022-09-26 13:57 ` [PATCH 4/4] mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol Johannes Weiner
2022-09-26 15:22   ` Shakeel Butt

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