[PATCH 00/11] implement DAMOS filtering for anon pages and

[PATCH 00/11] implement DAMOS filtering for anon pages and

[SeongJae Park]

Changes from RFC v2
(https://lore.kernel.org/damon/20221130200937.118005-1-sj@kernel.org/)
- Rebased on latest mm-unstable

----

DAMOS let users do system operations in a data access pattern oriented
way.  The data access pattern, which is extracted by DAMON, is somewhat
accurate more than what user space could know in many cases.  However,
in some situation, users could know something more than the kernel about
the pattern or some special requirements for some types of memory or
processes.  For example, some users would have slow swap devices and
knows latency-ciritical processes and therefore want to use DAMON-based
proactive reclamation (DAMON_RECLAIM) for only non-anonymous pages of
non-latency-critical processes.

For such restriction, users could exclude the memory regions from the
initial monitoring regions and use non-dynamic monitoring regions update
monitoring operations set including fvaddr and paddr.  They could also
adjust the DAMOS target access pattern.  For dynamically changing memory
layout and access pattern, those would be not enough.

To help the case, add an interface, namely DAMOS filters, which can be
used to avoid the DAMOS actions be applied to specific types of memory,
to DAMON kernel API (damon.h).  At the moment, it supports filtering
anonymous pages and/or specific memory cgroups in or out for each DAMOS
scheme.

This patchset adds the support for all DAMOS actions that 'paddr'
monitoring operations set supports ('pageout', 'lru_prio', and
'lru_deprio'), and the functionality is exposed via DAMON kernel API
(damon.h) the DAMON sysfs interface (/sys/kernel/mm/damon/admins/), and
DAMON_RECLAIM module parameters.

Patches Sequence
----------------

First patch implements DAMOS filter interface to DAMON kernel API.
Second patch makes the physical address space monitoring operations set
to support the filters from all supporting DAMOS actions.  Third patch
adds anonymous pages filter support to DAMON_RECLAIM, and the fourth
patch documents the DAMON_RECLAIM's new feature.  Fifth to seventh
patches implement DAMON sysfs files for support of the filters, and
eighth patch connects the file to use DAMOS filters feature.  Ninth
patch adds simple self test cases for DAMOS filters of the sysfs
interface.  Finally, following two patches (tenth and eleventh) document
the new features and interfaces.

Patchset History
----------------

Changes from RFC v2
(https://lore.kernel.org/damon/20221130200937.118005-1-sj@kernel.org/)
- Rebased on latest mm-unstable

Changes from RFC v1
(https://lore.kernel.org/damon/20221124212114.136863-1-sj@kernel.org/)
- sysfs: Clean up filters directory from scheme directory cleanup path
- sysfs: Link newly created filter to the scheme
- sysfs: Ignore removed memcg when checking path
- sysfs: Guard 'struct mem_cgroup' access with CONFIG_MEMCG
  (kernel test robot)

SeongJae Park (11):
  mm/damon/core: implement damos filter
  mm/damon/paddr: support DAMOS filters
  mm/damon/reclaim: add a parameter called skip_anon for avoiding
    anonymous pages reclamation
  Docs/admin-guide/damon/reclaim: document 'skip_anon' parameter
  mm/damon/sysfs-schemes: implement filters directory
  mm/damon/sysfs-schemes: implement filter directory
  mm/damon/sysfs-schemes: connect filter directory and filters directory
  mm/damon/sysfs-schemes: implement scheme filters
  selftests/damon/sysfs: test filters directory
  Docs/admin-guide/mm/damon/usage: document DAMOS filters of sysfs
  Docs/ABI/damon: document scheme filters files

 .../ABI/testing/sysfs-kernel-mm-damon         |  29 ++
 .../admin-guide/mm/damon/reclaim.rst          |   9 +
 Documentation/admin-guide/mm/damon/usage.rst  |  48 ++-
 include/linux/damon.h                         |  51 +++
 mm/damon/core.c                               |  39 ++
 mm/damon/paddr.c                              |  71 +++-
 mm/damon/reclaim.c                            |  19 +
 mm/damon/sysfs-schemes.c                      | 370 +++++++++++++++++-
 tools/testing/selftests/damon/sysfs.sh        |  29 ++
 9 files changed, 652 insertions(+), 13 deletions(-)

-- 
2.25.1

[PATCH 01/11] mm/damon/core: implement damos filter

[SeongJae Park]

DAMOS let users do system operation in a data access pattern oriented
way.  The data access pattern, which is extracted by DAMON, is somewhat
accurate more than what user space could know in many cases.  However,
in some situation, users could know something more than the kernel about
the pattern or some special requirements for some types of memory or
processes.  For example, some users would have slow swap devices and
knows latency-ciritical processes and therefore want to use DAMON-based
proactive reclamation (DAMON_RECLAIM) for only non-anonymous pages of
non-latency-critical processes.

For such restriction, users could exclude the memory regions from the
initial monitoring regions and use non-dynamic monitoring regions update
monitoring operations set including fvaddr and paddr.  They could also
adjust the DAMOS target access pattern.  For dynamically changing memory
layout and access pattern, those would be not enough.

To help the case, add an interface, namely DAMOS filters, which can be
used to avoid the DAMOS actions be applied to specific types of memory,
to DAMON kernel API (damon.h).  At the moment, it supports filtering
anonymous pages and/or specific memory cgroups in or out for each DAMOS
scheme.

Note that this commit adds only the interface to the DAMON kernel API.
The impelmentation should be made in the monitoring operations sets, and
following commits will add that.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 include/linux/damon.h | 51 +++++++++++++++++++++++++++++++++++++++++++
 mm/damon/core.c       | 39 +++++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 35630634d790..42cea3bf7319 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -8,6 +8,7 @@
 #ifndef _DAMON_H_
 #define _DAMON_H_
 
+#include <linux/memcontrol.h>
 #include <linux/mutex.h>
 #include <linux/time64.h>
 #include <linux/types.h>
@@ -215,6 +216,39 @@ struct damos_stat {
 	unsigned long qt_exceeds;
 };
 
+/**
+ * enum damos_filter_type - Type of memory for &struct damos_filter
+ * @DAMOS_FILTER_TYPE_ANON:	Anonymous pages.
+ * @DAMOS_FILTER_TYPE_MEMCG:	Specific memcg's pages.
+ * @NR_DAMOS_FILTER_TYPES:	Number of filter types.
+ */
+enum damos_filter_type {
+	DAMOS_FILTER_TYPE_ANON,
+	DAMOS_FILTER_TYPE_MEMCG,
+	NR_DAMOS_FILTER_TYPES,
+};
+
+/**
+ * struct damos_filter - DAMOS action target memory filter.
+ * @type:	Type of the page.
+ * @matching:	If the matching page should filtered out or in.
+ * @memcg_id:	Memcg id of the question if @type is DAMOS_FILTER_MEMCG.
+ * @list:	List head for siblings.
+ *
+ * Before applying the &damos->action to a memory region, DAMOS checks if each
+ * page of the region matches to this and avoid applying the action if so.
+ * Note that the check support is up to &struct damon_operations
+ * implementation.
+ */
+struct damos_filter {
+	enum damos_filter_type type;
+	bool matching;
+	union {
+		unsigned short memcg_id;
+	};
+	struct list_head list;
+};
+
 /**
  * struct damos_access_pattern - Target access pattern of the given scheme.
  * @min_sz_region:	Minimum size of target regions.
@@ -239,6 +273,7 @@ struct damos_access_pattern {
  * @action:		&damo_action to be applied to the target regions.
  * @quota:		Control the aggressiveness of this scheme.
  * @wmarks:		Watermarks for automated (in)activation of this scheme.
+ * @filters:		Additional set of &struct damos_filter for &action.
  * @stat:		Statistics of this scheme.
  * @list:		List head for siblings.
  *
@@ -254,6 +289,10 @@ struct damos_access_pattern {
  * If all schemes that registered to a &struct damon_ctx are inactive, DAMON
  * stops monitoring and just repeatedly checks the watermarks.
  *
+ * Before applying the &action to a memory region, &struct damon_operations
+ * implementation could check pages of the region and skip &action to respect
+ * &filters
+ *
  * After applying the &action to each region, &stat_count and &stat_sz is
  * updated to reflect the number of regions and total size of regions that the
  * &action is applied.
@@ -263,6 +302,7 @@ struct damos {
 	enum damos_action action;
 	struct damos_quota quota;
 	struct damos_watermarks wmarks;
+	struct list_head filters;
 	struct damos_stat stat;
 	struct list_head list;
 };
@@ -516,6 +556,12 @@ static inline unsigned long damon_sz_region(struct damon_region *r)
 #define damon_for_each_scheme_safe(s, next, ctx) \
 	list_for_each_entry_safe(s, next, &(ctx)->schemes, list)
 
+#define damos_for_each_filter(f, scheme) \
+	list_for_each_entry(f, &(scheme)->filters, list)
+
+#define damos_for_each_filter_safe(f, next, scheme) \
+	list_for_each_entry_safe(f, next, &(scheme)->filters, list)
+
 #ifdef CONFIG_DAMON
 
 struct damon_region *damon_new_region(unsigned long start, unsigned long end);
@@ -536,6 +582,11 @@ void damon_destroy_region(struct damon_region *r, struct damon_target *t);
 int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 		unsigned int nr_ranges);
 
+struct damos_filter *damos_new_filter(enum damos_filter_type type,
+		bool matching);
+void damos_add_filter(struct damos *s, struct damos_filter *f);
+void damos_destroy_filter(struct damos_filter *f);
+
 struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
 			enum damos_action action, struct damos_quota *quota,
 			struct damos_watermarks *wmarks);
diff --git a/mm/damon/core.c b/mm/damon/core.c
index ceec75b88ef9..1bf0654ae189 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -263,6 +263,40 @@ int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges,
 	return 0;
 }
 
+struct damos_filter *damos_new_filter(enum damos_filter_type type,
+		bool matching)
+{
+	struct damos_filter *filter;
+
+	filter = kmalloc(sizeof(*filter), GFP_KERNEL);
+	if (!filter)
+		return NULL;
+	filter->type = type;
+	filter->matching = matching;
+	return filter;
+}
+
+void damos_add_filter(struct damos *s, struct damos_filter *f)
+{
+	list_add_tail(&f->list, &s->filters);
+}
+
+static void damos_del_filter(struct damos_filter *f)
+{
+	list_del(&f->list);
+}
+
+static void damos_free_filter(struct damos_filter *f)
+{
+	kfree(f);
+}
+
+void damos_destroy_filter(struct damos_filter *f)
+{
+	damos_del_filter(f);
+	damos_free_filter(f);
+}
+
 /* initialize private fields of damos_quota and return the pointer */
 static struct damos_quota *damos_quota_init_priv(struct damos_quota *quota)
 {
@@ -287,6 +321,7 @@ struct damos *damon_new_scheme(struct damos_access_pattern *pattern,
 		return NULL;
 	scheme->pattern = *pattern;
 	scheme->action = action;
+	INIT_LIST_HEAD(&scheme->filters);
 	scheme->stat = (struct damos_stat){};
 	INIT_LIST_HEAD(&scheme->list);
 
@@ -315,6 +350,10 @@ static void damon_free_scheme(struct damos *s)
 
 void damon_destroy_scheme(struct damos *s)
 {
+	struct damos_filter *f, *next;
+
+	damos_for_each_filter_safe(f, next, s)
+		damos_destroy_filter(f);
 	damon_del_scheme(s);
 	damon_free_scheme(s);
 }
-- 
2.25.1

[PATCH 02/11] mm/damon/paddr: support DAMOS filters

[SeongJae Park]

Implement support of the DAMOS filters in the physical address space
monitoring operations set, for all DAMOS actions that it supports
including 'pageout', 'lru_prio', and 'lru_deprio'.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/paddr.c | 71 ++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 62 insertions(+), 9 deletions(-)

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index e1a4315c4be6..ebd1905eed6f 100644
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -202,7 +202,47 @@ static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
 	return max_nr_accesses;
 }
 
-static unsigned long damon_pa_pageout(struct damon_region *r)
+static bool __damos_pa_filter_out(struct damos_filter *filter,
+		struct page *page)
+{
+	bool matched = false;
+	struct mem_cgroup *memcg;
+
+	switch (filter->type) {
+	case DAMOS_FILTER_TYPE_ANON:
+		matched = PageAnon(page);
+		break;
+	case DAMOS_FILTER_TYPE_MEMCG:
+		rcu_read_lock();
+		memcg = page_memcg_check(page);
+		if (!memcg)
+			matched = false;
+		else
+			matched = filter->memcg_id == mem_cgroup_id(memcg);
+		rcu_read_unlock();
+		break;
+	default:
+		break;
+	}
+
+	return matched == filter->matching;
+}
+
+/*
+ * damos_pa_filter_out - Return true if the page should be filtered out.
+ */
+static bool damos_pa_filter_out(struct damos *scheme, struct page *page)
+{
+	struct damos_filter *filter;
+
+	damos_for_each_filter(filter, scheme) {
+		if (__damos_pa_filter_out(filter, page))
+			return true;
+	}
+	return false;
+}
+
+static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
 {
 	unsigned long addr, applied;
 	LIST_HEAD(page_list);
@@ -213,6 +253,11 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
 		if (!page)
 			continue;
 
+		if (damos_pa_filter_out(s, page)) {
+			put_page(page);
+			continue;
+		}
+
 		ClearPageReferenced(page);
 		test_and_clear_page_young(page);
 		if (isolate_lru_page(page)) {
@@ -232,7 +277,7 @@ static unsigned long damon_pa_pageout(struct damon_region *r)
 }
 
 static inline unsigned long damon_pa_mark_accessed_or_deactivate(
-		struct damon_region *r, bool mark_accessed)
+		struct damon_region *r, struct damos *s, bool mark_accessed)
 {
 	unsigned long addr, applied = 0;
 
@@ -241,6 +286,12 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
 
 		if (!page)
 			continue;
+
+		if (damos_pa_filter_out(s, page)) {
+			put_page(page);
+			continue;
+		}
+
 		if (mark_accessed)
 			mark_page_accessed(page);
 		else
@@ -251,14 +302,16 @@ static inline unsigned long damon_pa_mark_accessed_or_deactivate(
 	return applied * PAGE_SIZE;
 }
 
-static unsigned long damon_pa_mark_accessed(struct damon_region *r)
+static unsigned long damon_pa_mark_accessed(struct damon_region *r,
+	struct damos *s)
 {
-	return damon_pa_mark_accessed_or_deactivate(r, true);
+	return damon_pa_mark_accessed_or_deactivate(r, s, true);
 }
 
-static unsigned long damon_pa_deactivate_pages(struct damon_region *r)
+static unsigned long damon_pa_deactivate_pages(struct damon_region *r,
+	struct damos *s)
 {
-	return damon_pa_mark_accessed_or_deactivate(r, false);
+	return damon_pa_mark_accessed_or_deactivate(r, s, false);
 }
 
 static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
@@ -267,11 +320,11 @@ static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
 {
 	switch (scheme->action) {
 	case DAMOS_PAGEOUT:
-		return damon_pa_pageout(r);
+		return damon_pa_pageout(r, scheme);
 	case DAMOS_LRU_PRIO:
-		return damon_pa_mark_accessed(r);
+		return damon_pa_mark_accessed(r, scheme);
 	case DAMOS_LRU_DEPRIO:
-		return damon_pa_deactivate_pages(r);
+		return damon_pa_deactivate_pages(r, scheme);
 	case DAMOS_STAT:
 		break;
 	default:
-- 
2.25.1

[PATCH 03/11] mm/damon/reclaim: add a parameter called skip_anon for avoiding anonymous pages reclamation

[SeongJae Park]

In some cases, for example if users have confidence at anonymous pages
management or the swap device is too slow, users would want to avoid
DAMON_RECLAIM swapping the anonymous pages out.  For such case, add yet
another DAMON_RECLAIM parameter, namely 'skip_anon'.  When it is set as
'Y', DAMON_RECLAIM will avoid reclaiming anonymous pages using a DAMOS
filter.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/reclaim.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index e82631f39481..648d2a85523a 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -98,6 +98,15 @@ module_param(monitor_region_start, ulong, 0600);
 static unsigned long monitor_region_end __read_mostly;
 module_param(monitor_region_end, ulong, 0600);
 
+/*
+ * Skip anonymous pages reclamation.
+ *
+ * If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
+ * pages.  By default, ``N``.
+ */
+static bool skip_anon __read_mostly;
+module_param(skip_anon, bool, 0600);
+
 /*
  * PID of the DAMON thread
  *
@@ -142,6 +151,7 @@ static struct damos *damon_reclaim_new_scheme(void)
 static int damon_reclaim_apply_parameters(void)
 {
 	struct damos *scheme;
+	struct damos_filter *filter;
 	int err = 0;
 
 	err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
@@ -152,6 +162,15 @@ static int damon_reclaim_apply_parameters(void)
 	scheme = damon_reclaim_new_scheme();
 	if (!scheme)
 		return -ENOMEM;
+	if (skip_anon) {
+		filter = damos_new_filter(DAMOS_FILTER_TYPE_ANON, true);
+		if (!filter) {
+			/* Will be freed by next 'damon_set_schemes()' below */
+			damon_destroy_scheme(scheme);
+			return -ENOMEM;
+		}
+		damos_add_filter(scheme, filter);
+	}
 	damon_set_schemes(ctx, &scheme, 1);
 
 	return damon_set_region_biggest_system_ram_default(target,
-- 
2.25.1

[PATCH 04/11] Docs/admin-guide/damon/reclaim: document 'skip_anon' parameter

[SeongJae Park]

Document the newly added 'skip_anon' parameter of DAMON_RECLAIM, which
can be used to avoid anonymous pages reclamation.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/reclaim.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/admin-guide/mm/damon/reclaim.rst b/Documentation/admin-guide/mm/damon/reclaim.rst
index 4f1479a11e63..ff335e96e0d8 100644
--- a/Documentation/admin-guide/mm/damon/reclaim.rst
+++ b/Documentation/admin-guide/mm/damon/reclaim.rst
@@ -205,6 +205,15 @@ The end physical address of memory region that DAMON_RECLAIM will do work
 against.  That is, DAMON_RECLAIM will find cold memory regions in this region
 and reclaims.  By default, biggest System RAM is used as the region.
 
+skip_anon
+---------
+
+Skip anonymous pages reclamation.
+
+If this parameter is set as ``Y``, DAMON_RECLAIM does not reclaim anonymous
+pages.  By default, ``N``.
+
+
 kdamond_pid
 -----------
 
-- 
2.25.1

[PATCH 05/11] mm/damon/sysfs-schemes: implement filters directory

[SeongJae Park]

DAMOS filters is currently supported by only DAMON kernel API.  To
expose the feature to user space, implement a DAMON sysfs directory
named 'filters' under each scheme directory.  Please note that this is
implementing only the directory.  Following commits will implement more
files and directories, and finally connect the DAMOS filters feature.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 85 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 84 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 81fc4d27f4e4..50c8148cb474 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -258,6 +258,63 @@ static struct kobj_type damon_sysfs_stats_ktype = {
 	.default_groups = damon_sysfs_stats_groups,
 };
 
+/*
+ * filters directory
+ */
+
+struct damon_sysfs_scheme_filters {
+	struct kobject kobj;
+	int nr;
+};
+
+static struct damon_sysfs_scheme_filters *
+damon_sysfs_scheme_filters_alloc(void)
+{
+	return kzalloc(sizeof(struct damon_sysfs_scheme_filters), GFP_KERNEL);
+}
+
+static ssize_t nr_filters_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filters *filters = container_of(kobj,
+			struct damon_sysfs_scheme_filters, kobj);
+
+	return sysfs_emit(buf, "%d\n", filters->nr);
+}
+
+static ssize_t nr_filters_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	int nr, err = kstrtoint(buf, 0, &nr);
+
+	if (err)
+		return err;
+	if (nr < 0)
+		return -EINVAL;
+
+	return count;
+}
+
+static void damon_sysfs_scheme_filters_release(struct kobject *kobj)
+{
+	kfree(container_of(kobj, struct damon_sysfs_scheme_filters, kobj));
+}
+
+static struct kobj_attribute damon_sysfs_scheme_filters_nr_attr =
+		__ATTR_RW_MODE(nr_filters, 0600);
+
+static struct attribute *damon_sysfs_scheme_filters_attrs[] = {
+	&damon_sysfs_scheme_filters_nr_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_scheme_filters);
+
+static struct kobj_type damon_sysfs_scheme_filters_ktype = {
+	.release = damon_sysfs_scheme_filters_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_scheme_filters_groups,
+};
+
 /*
  * watermarks directory
  */
@@ -784,6 +841,7 @@ struct damon_sysfs_scheme {
 	struct damon_sysfs_access_pattern *access_pattern;
 	struct damon_sysfs_quotas *quotas;
 	struct damon_sysfs_watermarks *watermarks;
+	struct damon_sysfs_scheme_filters *filters;
 	struct damon_sysfs_stats *stats;
 	struct damon_sysfs_scheme_regions *tried_regions;
 };
@@ -878,6 +936,24 @@ static int damon_sysfs_scheme_set_watermarks(struct damon_sysfs_scheme *scheme)
 	return err;
 }
 
+static int damon_sysfs_scheme_set_filters(struct damon_sysfs_scheme *scheme)
+{
+	struct damon_sysfs_scheme_filters *filters =
+		damon_sysfs_scheme_filters_alloc();
+	int err;
+
+	if (!filters)
+		return -ENOMEM;
+	err = kobject_init_and_add(&filters->kobj,
+			&damon_sysfs_scheme_filters_ktype, &scheme->kobj,
+			"filters");
+	if (err)
+		kobject_put(&filters->kobj);
+	else
+		scheme->filters = filters;
+	return err;
+}
+
 static int damon_sysfs_scheme_set_stats(struct damon_sysfs_scheme *scheme)
 {
 	struct damon_sysfs_stats *stats = damon_sysfs_stats_alloc();
@@ -926,9 +1002,12 @@ static int damon_sysfs_scheme_add_dirs(struct damon_sysfs_scheme *scheme)
 	err = damon_sysfs_scheme_set_watermarks(scheme);
 	if (err)
 		goto put_quotas_access_pattern_out;
-	err = damon_sysfs_scheme_set_stats(scheme);
+	err = damon_sysfs_scheme_set_filters(scheme);
 	if (err)
 		goto put_watermarks_quotas_access_pattern_out;
+	err = damon_sysfs_scheme_set_stats(scheme);
+	if (err)
+		goto put_filters_watermarks_quotas_access_pattern_out;
 	err = damon_sysfs_scheme_set_tried_regions(scheme);
 	if (err)
 		goto put_tried_regions_out;
@@ -937,6 +1016,9 @@ static int damon_sysfs_scheme_add_dirs(struct damon_sysfs_scheme *scheme)
 put_tried_regions_out:
 	kobject_put(&scheme->tried_regions->kobj);
 	scheme->tried_regions = NULL;
+put_filters_watermarks_quotas_access_pattern_out:
+	kobject_put(&scheme->filters->kobj);
+	scheme->filters = NULL;
 put_watermarks_quotas_access_pattern_out:
 	kobject_put(&scheme->watermarks->kobj);
 	scheme->watermarks = NULL;
@@ -956,6 +1038,7 @@ static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 	damon_sysfs_quotas_rm_dirs(scheme->quotas);
 	kobject_put(&scheme->quotas->kobj);
 	kobject_put(&scheme->watermarks->kobj);
+	kobject_put(&scheme->filters->kobj);
 	kobject_put(&scheme->stats->kobj);
 	damon_sysfs_scheme_regions_rm_dirs(scheme->tried_regions);
 	kobject_put(&scheme->tried_regions->kobj);
-- 
2.25.1

[PATCH 06/11] mm/damon/sysfs-schemes: implement filter directory

[SeongJae Park]

Implement DAMOS filter directory which will be located under the filters
directory.  The directory provides three files, namely type, matching,
and memcg_path.  'type' and 'matching' will be directly connected to the
fields of 'struct damos_filter' having same name.  'memcg_path' will
receive the path of the memory cgroup of the interest and later
converted to memcg id when it's committed.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 128 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 50c8148cb474..afbfc55a8e84 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -258,6 +258,134 @@ static struct kobj_type damon_sysfs_stats_ktype = {
 	.default_groups = damon_sysfs_stats_groups,
 };
 
+/*
+ * filter directory
+ */
+
+struct damon_sysfs_scheme_filter {
+	struct kobject kobj;
+	enum damos_filter_type type;
+	bool matching;
+	char *memcg_path;
+};
+
+/* Should match with enum damos_filter_type */
+static const char * const damon_sysfs_scheme_filter_type_strs[] = {
+	"anon",
+	"memcg",
+};
+
+static ssize_t type_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%s\n",
+			damon_sysfs_scheme_filter_type_strs[filter->type]);
+}
+
+static ssize_t type_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	enum damos_filter_type type;
+	ssize_t ret = -EINVAL;
+
+	for (type = 0; type < NR_DAMOS_FILTER_TYPES; type++) {
+		if (sysfs_streq(buf, damon_sysfs_scheme_filter_type_strs[
+					type])) {
+			filter->type = type;
+			ret = count;
+			break;
+		}
+	}
+	return ret;
+}
+
+static ssize_t matching_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%c\n", filter->matching ? 'Y' : 'N');
+}
+
+static ssize_t matching_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	bool matching;
+	int err = kstrtobool(buf, &matching);
+
+	if (err)
+		return err;
+
+	filter->matching = matching;
+	return count;
+}
+
+static ssize_t memcg_path_show(struct kobject *kobj,
+		struct kobj_attribute *attr, char *buf)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	return sysfs_emit(buf, "%s\n",
+			filter->memcg_path ? filter->memcg_path : "");
+}
+
+static ssize_t memcg_path_store(struct kobject *kobj,
+		struct kobj_attribute *attr, const char *buf, size_t count)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+	char *path = kmalloc(sizeof(*path) * (count + 1), GFP_KERNEL);
+
+	if (!path)
+		return -ENOMEM;
+
+	strncpy(path, buf, count);
+	path[count] = '\0';
+	filter->memcg_path = path;
+	return count;
+}
+
+static void damon_sysfs_scheme_filter_release(struct kobject *kobj)
+{
+	struct damon_sysfs_scheme_filter *filter = container_of(kobj,
+			struct damon_sysfs_scheme_filter, kobj);
+
+	kfree(filter->memcg_path);
+	kfree(filter);
+}
+
+static struct kobj_attribute damon_sysfs_scheme_filter_type_attr =
+		__ATTR_RW_MODE(type, 0600);
+
+static struct kobj_attribute damon_sysfs_scheme_filter_matching_attr =
+		__ATTR_RW_MODE(matching, 0600);
+
+static struct kobj_attribute damon_sysfs_scheme_filter_memcg_path_attr =
+		__ATTR_RW_MODE(memcg_path, 0600);
+
+static struct attribute *damon_sysfs_scheme_filter_attrs[] = {
+	&damon_sysfs_scheme_filter_type_attr.attr,
+	&damon_sysfs_scheme_filter_matching_attr.attr,
+	&damon_sysfs_scheme_filter_memcg_path_attr.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(damon_sysfs_scheme_filter);
+
+static struct kobj_type damon_sysfs_scheme_filter_ktype = {
+	.release = damon_sysfs_scheme_filter_release,
+	.sysfs_ops = &kobj_sysfs_ops,
+	.default_groups = damon_sysfs_scheme_filter_groups,
+};
+
 /*
  * filters directory
  */
-- 
2.25.1

[PATCH 07/11] mm/damon/sysfs-schemes: connect filter directory and filters directory

[SeongJae Park]

Implement 'nr_filters' file under 'filters' directory, which will be
used to populate specific number of 'filter' directory under the
directory, similar to other 'nr_*' files in DAMON sysfs interface.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 68 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index afbfc55a8e84..e79c678a69d5 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -269,6 +269,11 @@ struct damon_sysfs_scheme_filter {
 	char *memcg_path;
 };
 
+static struct damon_sysfs_scheme_filter *damon_sysfs_scheme_filter_alloc(void)
+{
+	return kzalloc(sizeof(struct damon_sysfs_scheme_filter), GFP_KERNEL);
+}
+
 /* Should match with enum damos_filter_type */
 static const char * const damon_sysfs_scheme_filter_type_strs[] = {
 	"anon",
@@ -392,6 +397,7 @@ static struct kobj_type damon_sysfs_scheme_filter_ktype = {
 
 struct damon_sysfs_scheme_filters {
 	struct kobject kobj;
+	struct damon_sysfs_scheme_filter **filters_arr;
 	int nr;
 };
 
@@ -401,6 +407,57 @@ damon_sysfs_scheme_filters_alloc(void)
 	return kzalloc(sizeof(struct damon_sysfs_scheme_filters), GFP_KERNEL);
 }
 
+static void damon_sysfs_scheme_filters_rm_dirs(
+		struct damon_sysfs_scheme_filters *filters)
+{
+	struct damon_sysfs_scheme_filter **filters_arr = filters->filters_arr;
+	int i;
+
+	for (i = 0; i < filters->nr; i++)
+		kobject_put(&filters_arr[i]->kobj);
+	filters->nr = 0;
+	kfree(filters_arr);
+	filters->filters_arr = NULL;
+}
+
+static int damon_sysfs_scheme_filters_add_dirs(
+		struct damon_sysfs_scheme_filters *filters, int nr_filters)
+{
+	struct damon_sysfs_scheme_filter **filters_arr, *filter;
+	int err, i;
+
+	damon_sysfs_scheme_filters_rm_dirs(filters);
+	if (!nr_filters)
+		return 0;
+
+	filters_arr = kmalloc_array(nr_filters, sizeof(*filters_arr),
+			GFP_KERNEL | __GFP_NOWARN);
+	if (!filters_arr)
+		return -ENOMEM;
+	filters->filters_arr = filters_arr;
+
+	for (i = 0; i < nr_filters; i++) {
+		filter = damon_sysfs_scheme_filter_alloc();
+		if (!filter) {
+			damon_sysfs_scheme_filters_rm_dirs(filters);
+			return -ENOMEM;
+		}
+
+		err = kobject_init_and_add(&filter->kobj,
+				&damon_sysfs_scheme_filter_ktype,
+				&filters->kobj, "%d", i);
+		if (err) {
+			kobject_put(&filter->kobj);
+			damon_sysfs_scheme_filters_rm_dirs(filters);
+			return err;
+		}
+
+		filters_arr[i] = filter;
+		filters->nr++;
+	}
+	return 0;
+}
+
 static ssize_t nr_filters_show(struct kobject *kobj,
 		struct kobj_attribute *attr, char *buf)
 {
@@ -413,6 +470,7 @@ static ssize_t nr_filters_show(struct kobject *kobj,
 static ssize_t nr_filters_store(struct kobject *kobj,
 		struct kobj_attribute *attr, const char *buf, size_t count)
 {
+	struct damon_sysfs_scheme_filters *filters;
 	int nr, err = kstrtoint(buf, 0, &nr);
 
 	if (err)
@@ -420,6 +478,15 @@ static ssize_t nr_filters_store(struct kobject *kobj,
 	if (nr < 0)
 		return -EINVAL;
 
+	filters = container_of(kobj, struct damon_sysfs_scheme_filters, kobj);
+
+	if (!mutex_trylock(&damon_sysfs_lock))
+		return -EBUSY;
+	err = damon_sysfs_scheme_filters_add_dirs(filters, nr);
+	mutex_unlock(&damon_sysfs_lock);
+	if (err)
+		return err;
+
 	return count;
 }
 
@@ -1166,6 +1233,7 @@ static void damon_sysfs_scheme_rm_dirs(struct damon_sysfs_scheme *scheme)
 	damon_sysfs_quotas_rm_dirs(scheme->quotas);
 	kobject_put(&scheme->quotas->kobj);
 	kobject_put(&scheme->watermarks->kobj);
+	damon_sysfs_scheme_filters_rm_dirs(scheme->filters);
 	kobject_put(&scheme->filters->kobj);
 	kobject_put(&scheme->stats->kobj);
 	damon_sysfs_scheme_regions_rm_dirs(scheme->tried_regions);
-- 
2.25.1

[PATCH 08/11] mm/damon/sysfs-schemes: implement scheme filters

[SeongJae Park]

Implement scheme filters functionality of DAMON sysfs interface by
making the code reads the values of files under the filter directories
and pass that to DAMON using DAMON kernel API.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs-schemes.c | 89 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 88 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index e79c678a69d5..0501862534f2 100644
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -1403,6 +1403,75 @@ struct kobj_type damon_sysfs_schemes_ktype = {
 	.default_groups = damon_sysfs_schemes_groups,
 };
 
+static bool damon_sysfs_memcg_path_eq(struct mem_cgroup *memcg,
+		char *memcg_path_buf, char *path)
+{
+#ifdef CONFIG_MEMCG
+	cgroup_path(memcg->css.cgroup, memcg_path_buf, PATH_MAX);
+	if (sysfs_streq(memcg_path_buf, path))
+		return true;
+#endif /* CONFIG_MEMCG */
+	return false;
+}
+
+static int damon_sysfs_memcg_path_to_id(char *memcg_path, unsigned short *id)
+{
+	struct mem_cgroup *memcg;
+	char *path;
+
+	if (!memcg_path)
+		return -EINVAL;
+
+	path = kmalloc(sizeof(*path) * PATH_MAX, GFP_KERNEL);
+	if (!path)
+		return -ENOMEM;
+
+	for (memcg = mem_cgroup_iter(NULL, NULL, NULL); memcg;
+			memcg = mem_cgroup_iter(NULL, memcg, NULL)) {
+		/* skip removed memcg */
+		if (!mem_cgroup_id(memcg))
+			continue;
+		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
+			*id = mem_cgroup_id(memcg);
+			break;
+		}
+	}
+
+	kfree(path);
+	return 0;
+}
+
+static int damon_sysfs_set_scheme_filters(struct damos *scheme,
+		struct damon_sysfs_scheme_filters *sysfs_filters)
+{
+	int i;
+	struct damos_filter *filter, *next;
+
+	damos_for_each_filter_safe(filter, next, scheme)
+		damos_destroy_filter(filter);
+
+	for (i = 0; i < sysfs_filters->nr; i++) {
+		struct damon_sysfs_scheme_filter *sysfs_filter =
+			sysfs_filters->filters_arr[i];
+		struct damos_filter *filter =
+			damos_new_filter(sysfs_filter->type,
+					sysfs_filter->matching);
+		int err;
+
+		if (!filter)
+			return -ENOMEM;
+		if (filter->type == DAMOS_FILTER_TYPE_MEMCG) {
+			err = damon_sysfs_memcg_path_to_id(
+					sysfs_filter->memcg_path,
+					&filter->memcg_id);
+			if (err)
+				return err;
+		}
+		damos_add_filter(scheme, filter);
+	}
+	return 0;
+}
+
 static struct damos *damon_sysfs_mk_scheme(
 		struct damon_sysfs_scheme *sysfs_scheme)
 {
@@ -1411,6 +1480,10 @@ static struct damos *damon_sysfs_mk_scheme(
 	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
 	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
 	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
+	struct damon_sysfs_scheme_filters *sysfs_filters =
+		sysfs_scheme->filters;
+	struct damos *scheme;
+	int err;
 
 	struct damos_access_pattern pattern = {
 		.min_sz_region = access_pattern->sz->min,
@@ -1436,8 +1509,17 @@ static struct damos *damon_sysfs_mk_scheme(
 		.low = sysfs_wmarks->low,
 	};
 
-	return damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
+	scheme = damon_new_scheme(&pattern, sysfs_scheme->action, &quota,
 			&wmarks);
+	if (!scheme)
+		return NULL;
+
+	err = damon_sysfs_set_scheme_filters(scheme, sysfs_filters);
+	if (err) {
+		damon_destroy_scheme(scheme);
+		return NULL;
+	}
+	return scheme;
 }
 
 static void damon_sysfs_update_scheme(struct damos *scheme,
@@ -1448,6 +1530,7 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	struct damon_sysfs_quotas *sysfs_quotas = sysfs_scheme->quotas;
 	struct damon_sysfs_weights *sysfs_weights = sysfs_quotas->weights;
 	struct damon_sysfs_watermarks *sysfs_wmarks = sysfs_scheme->watermarks;
+	int err;
 
 	scheme->pattern.min_sz_region = access_pattern->sz->min;
 	scheme->pattern.max_sz_region = access_pattern->sz->max;
@@ -1470,6 +1553,10 @@ static void damon_sysfs_update_scheme(struct damos *scheme,
 	scheme->wmarks.high = sysfs_wmarks->high;
 	scheme->wmarks.mid = sysfs_wmarks->mid;
 	scheme->wmarks.low = sysfs_wmarks->low;
+
+	err = damon_sysfs_set_scheme_filters(scheme, sysfs_scheme->filters);
+	if (err)
+		damon_destroy_scheme(scheme);
 }
 
 int damon_sysfs_set_schemes(struct damon_ctx *ctx,
-- 
2.25.1

[PATCH 09/11] selftests/damon/sysfs: test filters directory

[SeongJae Park]

Add simple test cases for scheme filters of DAMON sysfs interface.  The
test cases check if the files are populated as expected, receives some
valid inputs, and refuses some invalid inputs.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 tools/testing/selftests/damon/sysfs.sh | 29 ++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/tools/testing/selftests/damon/sysfs.sh b/tools/testing/selftests/damon/sysfs.sh
index db4942383a50..a00336ffdcad 100644
--- a/tools/testing/selftests/damon/sysfs.sh
+++ b/tools/testing/selftests/damon/sysfs.sh
@@ -96,6 +96,34 @@ test_stats()
 	done
 }
 
+test_filter()
+{
+	filter_dir=$1
+	ensure_file "$filter_dir/type" "exist" "600"
+	ensure_write_succ "$filter_dir/type" "anon" "valid input"
+	ensure_write_succ "$filter_dir/type" "memcg" "valid input"
+	ensure_write_fail "$filter_dir/type" "foo" "invalid input"
+	ensure_file "$filter_dir/matching" "exist" "600"
+	ensure_file "$filter_dir/memcg_path" "exist" "600"
+}
+
+test_filters()
+{
+	filters_dir=$1
+	ensure_dir "$filters_dir" "exist"
+	ensure_file "$filters_dir/nr_filters" "exist" "600"
+	ensure_write_succ  "$filters_dir/nr_filters" "1" "valid input"
+	test_filter "$filters_dir/0"
+
+	ensure_write_succ  "$filters_dir/nr_filters" "2" "valid input"
+	test_filter "$filters_dir/0"
+	test_filter "$filters_dir/1"
+
+	ensure_write_succ "$filters_dir/nr_filters" "0" "valid input"
+	ensure_dir "$filters_dir/0" "not_exist"
+	ensure_dir "$filters_dir/1" "not_exist"
+}
+
 test_watermarks()
 {
 	watermarks_dir=$1
@@ -143,6 +171,7 @@ test_scheme()
 	test_access_pattern "$scheme_dir/access_pattern"
 	test_quotas "$scheme_dir/quotas"
 	test_watermarks "$scheme_dir/watermarks"
+	test_filters "$scheme_dir/filters"
 	test_stats "$scheme_dir/stats"
 	test_tried_regions "$scheme_dir/tried_regions"
 }
-- 
2.25.1

[PATCH 10/11] Docs/admin-guide/mm/damon/usage: document DAMOS filters of sysfs

[SeongJae Park]

Document about the newly added files for DAMOS filters on the DAMON
usage document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 48 +++++++++++++++++++-
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index 1a5b6b71efa1..3d82ca6a17ff 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -87,6 +87,8 @@ comma (","). ::
     │ │ │ │ │ │ │ quotas/ms,bytes,reset_interval_ms
     │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
     │ │ │ │ │ │ │ watermarks/metric,interval_us,high,mid,low
+    │ │ │ │ │ │ │ filters/nr_filters
+    │ │ │ │ │ │ │ │ 0/type,matching,memcg_id
     │ │ │ │ │ │ │ stats/nr_tried,sz_tried,nr_applied,sz_applied,qt_exceeds
     │ │ │ │ │ │ │ tried_regions/
     │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age
@@ -151,6 +153,8 @@ number (``N``) to the file creates the number of child directories named as
 moment, only one context per kdamond is supported, so only ``0`` or ``1`` can
 be written to the file.
 
+.. _sysfs_contexts:
+
 contexts/<N>/
 -------------
 
@@ -268,8 +272,8 @@ schemes/<N>/
 ------------
 
 In each scheme directory, five directories (``access_pattern``, ``quotas``,
-``watermarks``, ``stats``, and ``tried_regions``) and one file (``action``)
-exist.
+``watermarks``, ``filters``, ``stats``, and ``tried_regions``) and one file
+(``action``) exist.
 
 The ``action`` file is for setting and getting what action you want to apply to
 memory regions having specific access pattern of the interest.  The keywords
@@ -347,6 +351,46 @@ as below.
 
 The ``interval`` should written in microseconds unit.
 
+schemes/<N>/filters/
+--------------------
+
+Users could know something more than the kernel for specific types of memory.
+In the case, users could do their own management for the memory and hence
+doesn't want DAMOS bothers that.  Users could limit DAMOS by setting the access
+pattern of the scheme and/or the monitoring regions for the purpose, but that
+can be inefficient in some cases.  In such cases, users could set non-access
+pattern driven filters using files in this directory.
+
+In the beginning, this directory has only one file, ``nr_filters``.  Writing a
+number (``N``) to the file creates the number of child directories named ``0``
+to ``N-1``.  Each directory represents each filter.  The filters are evaluated
+in the numeric order.
+
+Each filter directory contains three files, namely ``type``, ``matcing``, and
+``memcg_path``.  You can write one of two special keywords, ``anon`` for
+anonymous pages, or ``memcg`` for specific memory cgroup filtering.  In case of
+the memory cgroup filtering, you can specify the memory cgroup of the interest
+by writing the path of the memory cgroup from the cgroups mount point to
+``memcg_path`` file.  You can write ``Y`` or ``N`` to ``matching`` file to
+filter out pages that does or does not match to the type, respectively.  Then,
+the scheme's action will not be applied to the pages that specified to be
+filtered out.
+
+For example, below restricts a DAMOS action to be applied to only non-anonymous
+pages of all memory cgroups except ``/having_care_already``.::
+
+    # echo 2 > nr_filters
+    # # filter out anonymous pages
+    echo anon > 0/type
+    echo Y > 0/matching
+    # # further filter out all cgroups except one at '/having_care_already'
+    echo memcg > 1/type
+    echo /having_care_already > 1/memcg_path
+    echo N > 1/matching
+
+Note that filters could be ignored depend on the running DAMON operations set
+`implementation <sysfs_contexts>`.
+
 .. _sysfs_schemes_stats:
 
 schemes/<N>/stats/
-- 
2.25.1

[PATCH 11/11] Docs/ABI/damon: document scheme filters files

[SeongJae Park]

Document newly added DAMON sysfs interface files for DAMOS filtering on
the DAMON ABI document.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
 .../ABI/testing/sysfs-kernel-mm-damon         | 29 +++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-kernel-mm-damon b/Documentation/ABI/testing/sysfs-kernel-mm-damon
index 13397b853692..2744f21b5a6b 100644
--- a/Documentation/ABI/testing/sysfs-kernel-mm-damon
+++ b/Documentation/ABI/testing/sysfs-kernel-mm-damon
@@ -258,6 +258,35 @@ Contact:	SeongJae Park <sj@kernel.org>
 Description:	Writing to and reading from this file sets and gets the low
 		watermark of the scheme in permil.
 
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/nr_filters
+Date:		Dec 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing a number 'N' to this file creates the number of
+		directories for setting filters of the scheme named '0' to
+		'N-1' under the filters/ directory.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/<F>/type
+Date:		Dec 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing to and reading from this file sets and gets the type of
+		the memory of the interest.  'anon' for anonymous pages, or
+		'memcg' for specific memory cgroup can be written and read.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/<F>/memcg_path
+Date:		Dec 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	If 'memcg' is written to the 'type' file, writing to and
+		reading from this file sets and gets the path to the memory
+		cgroup of the interest.
+
+What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/filters/<F>/matching
+Date:		Dec 2022
+Contact:	SeongJae Park <sj@kernel.org>
+Description:	Writing 'Y' or 'N' to this file sets whether to filter out
+		pages that do or do not match to the 'type' and 'memcg_path',
+		respectively.  Filter out means the action of the scheme will
+		not be applied to.
+
 What:		/sys/kernel/mm/damon/admin/kdamonds/<K>/contexts/<C>/schemes/<S>/stats/nr_tried
 Date:		Mar 2022
 Contact:	SeongJae Park <sj@kernel.org>
-- 
2.25.1

Re: [PATCH 00/11] implement DAMOS filtering for anon pages and

[Andrew Morton]

On Mon,  5 Dec 2022 23:08:19 +0000 SeongJae Park <sj@kernel.org> wrote:

> Subject: [PATCH 00/11] implement DAMOS filtering for anon pages and

I rewrote this to

implement DAMOS filtering for anon pages and/or specific memory cgroups

Re: [PATCH 00/11] implement DAMOS filtering for anon pages and

[SeongJae Park]

On Fri, 16 Dec 2022 15:59:48 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:

> On Mon,  5 Dec 2022 23:08:19 +0000 SeongJae Park <sj@kernel.org> wrote:
> 
> > Subject: [PATCH 00/11] implement DAMOS filtering for anon pages and
> 
> I rewrote this to
> 
> implement DAMOS filtering for anon pages and/or specific memory cgroups

Sounds much better, thank you Andrew!


Thanks,
SJ