linux-stable.git/include/linux/damon.h, branch v7.2-rc3

mm/damon: add a kernel-doc comment for damon_ctx->rnd_state

2026-07-02T02:02:55+00:00

Fix below kernel document build warning:

    WARNING: ../include/linux/damon.h:909 struct member 'rnd_state' not described in 'damon_ctx'

Link: https://lore.kernel.org/20260628220808.98931-3-sj@kernel.org
Fixes: 9012c4e647df ("mm/damon: replace damon_rand() with a per-ctx lockless PRNG")
Signed-off-by: SJ Park 
Reported-by: Randy Dunlap 
Closes: https://lore.kernel.org/4df95955-b255-4e5a-90c4-35db02f3111f@infradead.org
Signed-off-by: Andrew Morton

mm/damon: add a kernel-doc comment for damon_ctx->probes

2026-07-02T02:02:55+00:00

The two fields of damon_ctx struct dont have their kernel-doc comments.
That causes kernel document builds to warn.  Fix those.


This patch (of 2):

Fix below document build warning:

    WARNING: ../include/linux/damon.h:909 struct member 'probes' not described in 'damon_ctx'

Link: https://lore.kernel.org/20260628220808.98931-1-sj@kernel.org
Link: https://lore.kernel.org/20260628220808.98931-2-sj@kernel.org
Fixes: 18c777859f28 ("mm/damon/core: embed damon_probe objects in damon_ctx")
Signed-off-by: SJ Park 
Reported-by: Randy Dunlap 
Closes: https://lore.kernel.org/4df95955-b255-4e5a-90c4-35db02f3111f@infradead.org
Signed-off-by: Andrew Morton

mm/damon/ops-common: handle extreme intervals in damon_hot_score()

2026-07-02T02:02:53+00:00

Fix three issues in damon_hot_score() that comes from wrong handling of
extreme (zero or too high) monitoring intervals user setup.

When the user sets sampling interval zero, damon_max_nr_accesses(), which
is called from damon_hot_score(), causes a divide-by-zero.  Needless to
say, it is a problem.

When the user sets the aggregation interval zero, the function returns
zero.  It is wrong, since the real maximum nr_acceses in the setup should
be one.  Worse yet, it can cause another divide-by-zero from its caller,
damon_hot_score(), since it uses damon_max_nr_accesses() return value as a
denominator.

When the user sets the aggregation interval very high, damon_hot_score()
could return a value out of [0, DAMOS_MAX_SCORE] range.  Since the return
value is used as an index to the regions_score_histogram array, which is
DAMOS_MAX_SCORE+1 size, it causes out of bounds array access.

The issues can be relatively easily reproduced like below.  The sysfs
write permission is required, though.

    # ./damo start --damos_action lru_prio --damos_quota_space 100M \
            --damos_quota_interval 1s
    # cd /sys/kernel/mm/damon/admin/kdamonds/0
    # echo 0 > contexts/0/monitoring_attrs/intervals/sample_us
    # echo 0 > contexts/0/monitoring_attrs/intervals/aggr_us
    # echo commit > state
    # dmesg
    [...]
    [  131.329762] Oops: divide error: 0000 [#1] SMP NOPTI
    [...]
    [  131.336089] RIP: 0010:damon_hot_score+0x27/0xd0
    [...]

Fix the divide-by-zero intervals problems by explicitly handling the zero
intervals in damon_max_nr_accesses().  Fix the out-of-bound array access
by applying [0, DAMOS_MAX_SCORE] bounds before returning from
damon_hot_score().

The issue was discovered [1] by Sashiko.

Link: https://lore.kernel.org/20260623135834.67189-1-sj@kernel.org
Link: https://lore.kernel.org/20260619202459.145010-1-sj@kernel.org [1]
Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization")
Signed-off-by: SeongJae Park 
Cc:  # 5.16.x
Signed-off-by: Andrew Morton

mm/damon: fix missing parens in macro arguments

2026-06-04T21:45:02+00:00

Patch series "mm/damon: fix macro arguments and clarify quota goals doc",
v2.


This patch (of 2):

The DAMON iterator macros do not wrap their pointer arguments with
parentheses.  This can cause build failures when the argument is a complex
expression due to operator precedence issues.

Add missing parentheses around the arguments in the following macros
to prevent potential build failures:
- damon_for_each_region()
- damon_for_each_region_from()
- damon_for_each_region_safe()
- damos_for_each_quota_goal()

Link: https://lore.kernel.org/20260521202020.126500-1-maksym.shcherba@lnu.edu.ua
Link: https://lore.kernel.org/20260521202020.126500-2-maksym.shcherba@lnu.edu.ua
Signed-off-by: Maksym Shcherba 
Reviewed-by: SeongJae Park 
Assisted-by: Antigravity:Gemini-3.1-Pro
Signed-off-by: Andrew Morton

mm/damon/core: hide damon_destroy_region()

2026-06-04T21:45:01+00:00

damon_destroy_region() is being used by only DAMON core, but exposed to
DAMON API callers.  Exposing something that is not really being used by
others will only increase the maintenance cost.  Hide it.

Link: https://lore.kernel.org/20260522154026.80546-8-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Brendan Higgins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm/damon/core: hide damon_insert_region()

2026-06-04T21:45:01+00:00

damon_insert_region() is being used by only DAMON core, but exposed to
DAMON API callers.  Exposing something that is not really being used by
others will only increase the maintenance cost.  Hide it.

Link: https://lore.kernel.org/20260522154026.80546-7-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Brendan Higgins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm/damon/core: hide damon_add_region()

2026-06-04T21:45:00+00:00

damon_add_region() is being used by only DAMON core, but exposed to DAMON
API callers.  Exposing something that is not really being used by others
will only increase the maintenance cost.  Hide it.

Link: https://lore.kernel.org/20260522154026.80546-6-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: Brendan Higgins 
Cc: Shuah Khan 
Signed-off-by: Andrew Morton

mm/damon/sysfs: setup damon_filter->memcg_id from path

2026-06-02T22:22:31+00:00

Find and set the memcg_id for damon_filter from the user-passed memory
cgroup path when updating the DAMON input parameters.

Link: https://lore.kernel.org/20260518234119.97569-27-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: "Masami Hiramatsu (Google)" 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Steven Rostedt 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

mm/damon/core: introduce DAMON_FILTER_TYPE_MEMCG

2026-06-02T22:22:30+00:00

Belonging memory cgoup is another data attribute that can be useful to
monitor.  Introduce a new DAMON filter type, namely
DAMON_FILTER_TYPE_MEMCG, for monitoring of this attribute.

Link: https://lore.kernel.org/20260518234119.97569-23-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: "Masami Hiramatsu (Google)" 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Steven Rostedt 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

mm/damon/core: introduce damon_ops->apply_probes

2026-06-02T22:22:26+00:00

Extend damon_operations struct with a new callback, namely apply_probes. 
The callback will be invoked for data attributes monitoring.  More
specifically, the callback will apply damon_probe objects to each region
and update the per-region per-probe counters for the number of encountered
probe-positive samples.

Link: https://lore.kernel.org/20260518234119.97569-7-sj@kernel.org
Signed-off-by: SeongJae Park 
Cc: David Hildenbrand 
Cc: Jonathan Corbet 
Cc: Liam R. Howlett 
Cc: Lorenzo Stoakes 
Cc: "Masami Hiramatsu (Google)" 
Cc: Mathieu Desnoyers 
Cc: Michal Hocko 
Cc: Mike Rapoport 
Cc: Shuah Khan 
Cc: Steven Rostedt 
Cc: Suren Baghdasaryan 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton