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

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.


This patch (of 11):

DAMOS lets 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.

Link: https://lkml.kernel.org/r/20221205230830.144349-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20221205230830.144349-2-sj@kernel.org

Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>