[PATCH v4 0/2] mm/damon/core: Iterate over installed probes instead of DAMON_MAX_PROBES

[Suhaas Joshi]

Hello,

This is v4 of a series I sent earlier. Please find changelog below.

There were two "todo: " items of the same nature in mm/damon/core.c. Both
of these suggested that we should iterate over only installed probes while
updating (last_)probe_hits[] during merging/splitting regions, instead of
iterating over the entire array, which may have empty/unused indices.

So this patch series does exactly that. It replaces the for-loop over
[0, DAMON_MAX_PROBES) with a damon_for_each_probe() over the probe list of
the context.

These patches are based off mm-new. They pass all KUnit tests related to
damon. I have boot tested (but nothing beyond) on qemu-x86_64. Please do
let me know if I should do any specific tests and link the logs here.

The series has been tested with mm-new fetched on Oct 14, 2026.

Changes v3 -> v4:
1. In some places, kunit_skip() was being called before freeing resources.
   This is correctly ordered now.
2. In some places, regions were not being freed. In v4, they are being freed.
Link to v3: https://lore.kernel.org/damon/20261012145636.168436-1-suhaas@xxxxxxxxxx/T/#t

Changes v2 -> v3:
1. In test functions, new probe and context allocations happen after target,
   region etc have been allocated. Further, target is added to the context.
   These 2 changes help in reducing allocation code and improving simplicity
   and readability of the patches. This change is true for both patches.
   (on SJ suggestion)
2. Earlier, if a function's argument list required multiple lines, I was aligning
   these lines to the opening paranthesis of the function. In v3, these begin
   after 2 tab spaces. (On SJ suggestion)
3. damon_test_last_region_quota_reset() uses the older version of damos_skip_charged_region().
   Make it use the new version.
Link to v2: https://lore.kernel.org/damon/20261008151944.113714-1-suhaas@xxxxxxxxxx/

Changes v1 -> v2:
1. simplified commit message of patch 1 (on Liew's suggestion)
2. wrapped all lines at 80 characters (on SJ's suggestion)
3. added comments for new argument in function (on SJ's suggestion)
4. added damon_ctx_destroy() in r2 failure case in damon_test_merge_two()
   (on SJ/Sashiko/Liew suggestion)
Link to v1: https://lore.kernel.org/damon/20261007154851.45368-1-suhaas@xxxxxxxxxx/


Suhaas Joshi (2):
  mm/damon/core: Use only installed probe in damon_merge_two_regions()
  mm/damon/core: Copy only installed probe in damon_split_region_at()

 mm/damon/core.c             | 57 +++++++++++++++----------
 mm/damon/tests/core-kunit.h | 84 +++++++++++++++++++++++++++++++------
 2 files changed, 106 insertions(+), 35 deletions(-)


base-commit: beaba65d5704418b6fa03c96a389bc2c2b6702b8
-- 
2.55.0