From: Shaun Tancheff <shaun.tancheff@hpe.com>

For users that are unable to update to memcg-v2 this
provides a method where memcg-v1 can more effectively
apply enough memory pressure to effectively throttle
filesystem I/O or otherwise minimize being memcg oom
killed at the expense of reduced performance.

This patch extends the memcg-v1 legacy sysfs entries
with:
    limit_in_bytes.min, limit_in_bytes.low and
    limit_in_bytes.high
Since old software will need to be updated to take
advantage of the new files a secondary method
of setting min, low and high based on a percentage
of the limit is also provided. The percentages
are determined by module parameters.

The available module parameters can be set at
kernel boot time, for example:
   memcontrol.memcg_min=10
   memcontrol.memcg_low=30
   memcontrol.memcg_high=80

Would set min to 10%, low to 30% and high to 80% of
the value written to:
  /sys/fs/cgroup/memory/<grp>/memory.limit_in_bytes

Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
---
 mm/memcontrol.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5abffe6f8389..eec6e6ed92f8 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -73,6 +73,18 @@
 
 #include <trace/events/vmscan.h>
 
+static unsigned int memcg_v1_min_default_percent;
+module_param_named(memcg_min, memcg_v1_min_default_percent, uint, 0600);
+MODULE_PARM_DESC(memcg_min, "memcg v1 min default percent");
+
+static unsigned int memcg_v1_low_default_percent;
+module_param_named(memcg_low, memcg_v1_low_default_percent, uint, 0600);
+MODULE_PARM_DESC(memcg_low, "memcg v1 low default percent");
+
+static unsigned int memcg_v1_high_default_percent;
+module_param_named(memcg_high, memcg_v1_high_default_percent, uint, 0600);
+MODULE_PARM_DESC(memcg_high, "memcg v1 high default percent");
+
 struct cgroup_subsys memory_cgrp_subsys __read_mostly;
 EXPORT_SYMBOL(memory_cgrp_subsys);
 
@@ -208,6 +220,7 @@ enum res_type {
 	_MEMSWAP,
 	_KMEM,
 	_TCP,
+	_MEM_V1,
 };
 
 #define MEMFILE_PRIVATE(x, val)	((x) << 16 | (val))
@@ -3689,6 +3702,9 @@ enum {
 	RES_MAX_USAGE,
 	RES_FAILCNT,
 	RES_SOFT_LIMIT,
+	RES_LIMIT_MIN,
+	RES_LIMIT_LOW,
+	RES_LIMIT_HIGH,
 };
 
 static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
@@ -3699,6 +3715,7 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
 
 	switch (MEMFILE_TYPE(cft->private)) {
 	case _MEM:
+	case _MEM_V1:
 		counter = &memcg->memory;
 		break;
 	case _MEMSWAP:
@@ -3729,6 +3746,12 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
 		return counter->failcnt;
 	case RES_SOFT_LIMIT:
 		return (u64)memcg->soft_limit * PAGE_SIZE;
+	case RES_LIMIT_MIN:
+		return (u64)READ_ONCE(memcg->memory.min);
+	case RES_LIMIT_LOW:
+		return (u64)READ_ONCE(memcg->memory.low);
+	case RES_LIMIT_HIGH:
+		return (u64)READ_ONCE(memcg->memory.high);
 	default:
 		BUG();
 	}
@@ -3828,6 +3851,35 @@ static int memcg_update_tcp_max(struct mem_cgroup *memcg, unsigned long max)
 	return ret;
 }
 
+static inline void mem_cgroup_v1_set_defaults(struct mem_cgroup *memcg,
+					       u64 nr_pages)
+{
+	u64 max = (u64)(PAGE_COUNTER_MAX * PAGE_SIZE) / PAGE_SIZE;
+	u64 min, low, high;
+
+	if (mem_cgroup_is_root(memcg) || max == nr_pages)
+		return;
+
+	min = READ_ONCE(memcg->memory.min);
+	low = READ_ONCE(memcg->memory.low);
+	if (min || low)
+		return;
+
+	if (!min && memcg_v1_min_default_percent) {
+		min = (nr_pages * memcg_v1_min_default_percent) / 100;
+		page_counter_set_min(&memcg->memory, min);
+	}
+	if (!low && memcg_v1_low_default_percent) {
+		low = (nr_pages * memcg_v1_low_default_percent) / 100;
+		page_counter_set_low(&memcg->memory, low);
+	}
+	high = READ_ONCE(memcg->memory.high);
+	if (high == PAGE_COUNTER_MAX && memcg_v1_high_default_percent) {
+		high = (nr_pages * memcg_v1_high_default_percent) / 100;
+		page_counter_set_high(&memcg->memory, high);
+	}
+}
+
 /*
  * The user of this function is...
  * RES_LIMIT.
@@ -3851,6 +3903,11 @@ static ssize_t mem_cgroup_write(struct kernfs_open_file *of,
 			break;
 		}
 		switch (MEMFILE_TYPE(of_cft(of)->private)) {
+		case _MEM_V1:
+			ret = mem_cgroup_resize_max(memcg, nr_pages, false);
+			if (!ret)
+				mem_cgroup_v1_set_defaults(memcg, nr_pages);
+			break;
 		case _MEM:
 			ret = mem_cgroup_resize_max(memcg, nr_pages, false);
 			break;
@@ -4999,6 +5056,13 @@ static int mem_cgroup_slab_show(struct seq_file *m, void *p)
 }
 #endif
 
+static ssize_t memory_min_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off);
+static ssize_t memory_low_write(struct kernfs_open_file *of,
+				char *buf, size_t nbytes, loff_t off);
+static ssize_t memory_high_write(struct kernfs_open_file *of,
+				 char *buf, size_t nbytes, loff_t off);
+
 static struct cftype mem_cgroup_legacy_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -5013,10 +5077,28 @@ static struct cftype mem_cgroup_legacy_files[] = {
 	},
 	{
 		.name = "limit_in_bytes",
-		.private = MEMFILE_PRIVATE(_MEM, RES_LIMIT),
+		.private = MEMFILE_PRIVATE(_MEM_V1, RES_LIMIT),
 		.write = mem_cgroup_write,
 		.read_u64 = mem_cgroup_read_u64,
 	},
+	{
+		.name = "limit_in_bytes.min",
+		.private = MEMFILE_PRIVATE(_MEM_V1, RES_LIMIT_MIN),
+		.write = memory_min_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "limit_in_bytes.low",
+		.private = MEMFILE_PRIVATE(_MEM_V1, RES_LIMIT_LOW),
+		.write = memory_low_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
+	{
+		.name = "limit_in_bytes.high",
+		.private = MEMFILE_PRIVATE(_MEM_V1, RES_LIMIT_HIGH),
+		.write = memory_high_write,
+		.read_u64 = mem_cgroup_read_u64,
+	},
 	{
 		.name = "soft_limit_in_bytes",
 		.private = MEMFILE_PRIVATE(_MEM, RES_SOFT_LIMIT),
-- 
2.34.1

Hi Shaun,

kernel test robot noticed the following build errors:

[auto build test ERROR on v6.3-rc5]
[also build test ERROR on linus/master]
[cannot apply to akpm-mm/mm-everything next-20230404]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Shaun-Tancheff/memcg-v1-Enable-setting-memory-min-low-high/20230405-045143
patch link:    https://lore.kernel.org/r/20230404205013.31520-1-shaun.tancheff%40gmail.com
patch subject: [PATCH] memcg-v1: Enable setting memory min, low, high
config: m68k-randconfig-r023-20230403 (https://download.01.org/0day-ci/archive/20230405/202304051118.jpLmhRPu-lkp@intel.com/config)
compiler: m68k-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/180e4266c809a61c2711599c6462bd719efed76c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Shaun-Tancheff/memcg-v1-Enable-setting-memory-min-low-high/20230405-045143
        git checkout 180e4266c809a61c2711599c6462bd719efed76c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304051118.jpLmhRPu-lkp@intel.com/

All errors (new ones prefixed by >>):

   m68k-linux-ld: m68k-linux-ld: DWARF error: could not find abbrev number 99017497
   mm/memcontrol.o: in function `mem_cgroup_write':
>> memcontrol.c:(.text+0x4548): undefined reference to `__udivdi3'
>> m68k-linux-ld: memcontrol.c:(.text+0x45b4): undefined reference to `__udivdi3'
   m68k-linux-ld: memcontrol.c:(.text+0x45ec): undefined reference to `__udivdi3'
>> m68k-linux-ld: mm/memcontrol.o:(.debug_addr+0x1fc): undefined reference to `__udivdi3'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests

Hi Shaun,

kernel test robot noticed the following build errors:

[auto build test ERROR on v6.3-rc5]
[also build test ERROR on linus/master]
[cannot apply to akpm-mm/mm-everything next-20230404]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Shaun-Tancheff/memcg-v1-Enable-setting-memory-min-low-high/20230405-045143
patch link:    https://lore.kernel.org/r/20230404205013.31520-1-shaun.tancheff%40gmail.com
patch subject: [PATCH] memcg-v1: Enable setting memory min, low, high
config: i386-randconfig-a011-20230403 (https://download.01.org/0day-ci/archive/20230405/202304051011.6E3fABwV-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/180e4266c809a61c2711599c6462bd719efed76c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Shaun-Tancheff/memcg-v1-Enable-setting-memory-min-low-high/20230405-045143
        git checkout 180e4266c809a61c2711599c6462bd719efed76c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304051011.6E3fABwV-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: mm/memcontrol.o: in function `mem_cgroup_v1_set_defaults':
>> mm/memcontrol.c:3878: undefined reference to `__udivdi3'


vim +3878 mm/memcontrol.c

  3853	
  3854	static inline void mem_cgroup_v1_set_defaults(struct mem_cgroup *memcg,
  3855						       u64 nr_pages)
  3856	{
  3857		u64 max = (u64)(PAGE_COUNTER_MAX * PAGE_SIZE) / PAGE_SIZE;
  3858		u64 min, low, high;
  3859	
  3860		if (mem_cgroup_is_root(memcg) || max == nr_pages)
  3861			return;
  3862	
  3863		min = READ_ONCE(memcg->memory.min);
  3864		low = READ_ONCE(memcg->memory.low);
  3865		if (min || low)
  3866			return;
  3867	
  3868		if (!min && memcg_v1_min_default_percent) {
  3869			min = (nr_pages * memcg_v1_min_default_percent) / 100;
  3870			page_counter_set_min(&memcg->memory, min);
  3871		}
  3872		if (!low && memcg_v1_low_default_percent) {
  3873			low = (nr_pages * memcg_v1_low_default_percent) / 100;
  3874			page_counter_set_low(&memcg->memory, low);
  3875		}
  3876		high = READ_ONCE(memcg->memory.high);
  3877		if (high == PAGE_COUNTER_MAX && memcg_v1_high_default_percent) {
> 3878			high = (nr_pages * memcg_v1_high_default_percent) / 100;
  3879			page_counter_set_high(&memcg->memory, high);
  3880		}
  3881	}
  3882	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests