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Patch series "Extend DAMOS filters for address ranges and DAMON monitoring
targets"

There are use cases that need to apply DAMOS schemes to specific address
ranges or DAMON monitoring targets.  NUMA nodes in the physical address
space, special memory objects in the virtual address space, and monitoring
target specific efficient monitoring results snapshot retrieval could be
examples of such use cases.  This patchset extends DAMOS filters feature
for such cases, by implementing two more filter types, namely address
ranges and DAMON monitoring types.

Patches sequence
----------------

The first seven patches are for the address ranges based DAMOS filter. 
The first patch implements the filter feature and expose it via DAMON
kernel API.  The second patch further expose the feature to users via
DAMON sysfs interface.  The third and fourth patches implement unit tests
and selftests for the feature.  Three patches (fifth to seventh) updating
the documents follow.

The following six patches are for the DAMON monitoring target based DAMOS
filter.  The eighth patch implements the feature in the core layer and
expose it via DAMON's kernel API.  The ninth patch further expose it to
users via DAMON sysfs interface.  Tenth patch add a selftest, and two
patches (eleventh and twelfth) update documents.

[1] https://lore.kernel.org/damon/20230728203444.70703-1-sj@kernel.org/


This patch (of 13):

Users can know special characteristic of specific address ranges.  NUMA
nodes or special objects or buffers in virtual address space could be such
examples.  For such cases, DAMOS schemes could required to be applied to
only specific address ranges.  Implement yet another type of DAMOS filter
for the purpose.

Note that the existing filter types, namely anon pages and memcg DAMOS
filters needed page level type check.  Because such check can be done
efficiently in the opertions set layer, those filters are handled in
operations set layer.  Specifically, only paddr operations set
implementation supports these filters.  Also, because statistics counting
is done in the DAMON core layer, the regions that filtered out by these
filters are counted as tried but failed to the statistics.

Unlike those, address range based filters can efficiently handled in the
core layer.  Hence, do the handling in the layer, and count the regions
that filtered out by those as the scheme has not tried for the region. 
This difference should clearly documented.

Link: https://lkml.kernel.org/r/20230802214312.110532-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20230802214312.110532-2-sj@kernel.org

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