mm/damon: implement a new DAMOS filter type for unmapped pages

Patch series "mm/damon: introduce DAMOS filter type for unmapped pages".

User decides whether their memory will be mapped or unmapped.  It implies
that the two types of memory can have different characteristics and
management requirements.  Provide the DAMON-observaibility DAMOS-operation
capability for the different types by introducing a new DAMOS filter type
for unmapped pages.

This patch (of 2):

Implement yet another DAMOS filter type for unmapped pages on DAMON kernel
API, and add support of it from the physical address space DAMON
operations set (paddr).  Since it is for only unmapped pages, support from
the virtual address spaces DAMON operations set (vaddr) is not required.

Link: https://lkml.kernel.org/r/20250219220146.133650-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250219220146.133650-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/damon.h b/include/linux/damon.h
index 5e7ae7b..242910b 100644 (file)
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -337,6 +337,7 @@ struct damos_stat {
  * @DAMOS_FILTER_TYPE_MEMCG:   Specific memcg's pages.
  * @DAMOS_FILTER_TYPE_YOUNG:   Recently accessed pages.
  * @DAMOS_FILTER_TYPE_HUGEPAGE_SIZE:   Page is part of a hugepage.
+ * @DAMOS_FILTER_TYPE_UNMAPPED:        Unmapped pages.
  * @DAMOS_FILTER_TYPE_ADDR:    Address range.
  * @DAMOS_FILTER_TYPE_TARGET:  Data Access Monitoring target.
  * @NR_DAMOS_FILTER_TYPES:     Number of filter types.
@@ -357,6 +358,7 @@ enum damos_filter_type {
        DAMOS_FILTER_TYPE_MEMCG,
        DAMOS_FILTER_TYPE_YOUNG,
        DAMOS_FILTER_TYPE_HUGEPAGE_SIZE,
+       DAMOS_FILTER_TYPE_UNMAPPED,
        DAMOS_FILTER_TYPE_ADDR,
        DAMOS_FILTER_TYPE_TARGET,
        NR_DAMOS_FILTER_TYPES,

diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
index 1a59746..d5db313 100644 (file)
--- a/mm/damon/paddr.c
+++ b/mm/damon/paddr.c
@@ -236,6 +236,9 @@ static bool damos_pa_filter_match(struct damos_filter *filter,
                matched = filter->sz_range.min <= folio_sz &&
                          folio_sz <= filter->sz_range.max;
                break;
+       case DAMOS_FILTER_TYPE_UNMAPPED:
+               matched = !folio_mapped(folio) || !folio_raw_mapping(folio);
+               break;
        default:
                break;
        }

diff --git a/mm/damon/sysfs-schemes.c b/mm/damon/sysfs-schemes.c
index 881d00b..66a1c46 100644 (file)
--- a/mm/damon/sysfs-schemes.c
+++ b/mm/damon/sysfs-schemes.c
@@ -331,6 +331,7 @@ static const char * const damon_sysfs_scheme_filter_type_strs[] = {
        "memcg",
        "young",
        "hugepage_size",
+       "unmapped",
        "addr",
        "target",
 };