From 4a6ceb7c9744c69546d4ca43b7bd308f4db0927b Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Tue, 16 Dec 2025 00:01:14 -0800 Subject: mm/damon/core: introduce nr_snapshots damos stat Patch series "mm/damon: introduce {,max_}nr_snapshots and tracepoint for damos stats". Introduce three changes for improving DAMOS stat's provided information, deterministic control, and reading usability. DAMOS provides stats that are important for understanding its behavior. It lacks information about how many DAMON-generated monitoring output snapshots it has worked on. Add a new stat, nr_snapshots, to show the information. Users can control DAMOS schemes in multiple ways. Using the online parameters commit feature, they can install and uninstall DAMOS schemes whenever they want while keeping DAMON runs. DAMOS quotas and watermarks can be used for manually or automatically turning on/off or adjusting the aggressiveness of the scheme. DAMOS filters can be used for applying the scheme to specific memory entities based on their types and locations. Some users want their DAMOS scheme to be applied to only specific number of DAMON snapshots, for more deterministic control. One example use case is tracepoint based snapshot reading. Add a new knob, max_nr_snapshots, to support this. If the nr_snapshots parameter becomes same to or greater than the value of this parameter, the scheme is deactivated. Users can read DAMOS stats via DAMON's sysfs interface. For deep level investigations on environments having advanced tools like perf and bpftrace, exposing the stats via a tracepoint can be useful. Implement a new tracepoint, namely damon:damos_stat_after_apply_interval. First five patches (patches 1-5) of this series implement the new stat, nr_snapshots, on the core layer (patch 1), expose on DAMON sysfs user interface (patch 2), and update documents (patches 3-5). Following six patches (patches 6-11) are for the new stat based DAMOS deactivation (max_nr_snapshots). The first one (patch 6) of this group updates a kernel-doc comment before making further changes. Then an implementation of it on the core layer (patch 7), an introduction of a new DAMON sysfs interface file for users of the feature (patch 8), and three updates of the documents (patches 9-11) follow. The final one (patch 12) introduces the new tracepoint that exposes the DAMOS stat values for each scheme apply interval. This patch (of 12): DAMON generates monitoring results snapshots for every sampling interval. DAMOS applies given schemes on the regions of the snapshots, for every apply interval of the scheme. DAMOS stat informs a given scheme has tried to how many memory entities and applied, in the region and byte level. In some use cases including user-space oriented tuning and investigations, it is useful to know that in the DAMON-snapshot level. Introduce a new stat, namely nr_snapshots for DAMON core API callers. [sj@kernel.org: fix wrong list_is_last() call in damons_is_last_region()] Link: https://lkml.kernel.org/r/20260114152049.99727-1-sj@kernel.org Link: https://lkml.kernel.org/r/20251216080128.42991-1-sj@kernel.org Link: https://lkml.kernel.org/r/20251216080128.42991-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Michal Hocko Cc: Mike Rapoport Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/damon.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 3813373a9200..1d8a1515e75a 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -330,6 +330,8 @@ struct damos_watermarks { * @sz_ops_filter_passed: * Total bytes that passed ops layer-handled DAMOS filters. * @qt_exceeds: Total number of times the quota of the scheme has exceeded. + * @nr_snapshots: + * Total number of DAMON snapshots that the scheme has tried. * * "Tried an action to a region" in this context means the DAMOS core logic * determined the region as eligible to apply the action. The access pattern @@ -355,6 +357,7 @@ struct damos_stat { unsigned long sz_applied; unsigned long sz_ops_filter_passed; unsigned long qt_exceeds; + unsigned long nr_snapshots; }; /** -- cgit v1.2.3 From ccaa2d062a35add92832e8f082b8e00eed3f6efd Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Tue, 16 Dec 2025 00:01:19 -0800 Subject: mm/damon: update damos kerneldoc for stat field Commit 0e92c2ee9f45 ("mm/damon/schemes: account scheme actions that successfully applied") has replaced ->stat_count and ->stat_sz of 'struct damos' with ->stat. The commit mistakenly did not update the related kernel doc comment, though. Update the comment. Link: https://lkml.kernel.org/r/20251216080128.42991-7-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Michal Hocko Cc: Mike Rapoport Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/damon.h | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 1d8a1515e75a..43dfbfe2292f 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -532,9 +532,7 @@ struct damos_migrate_dests { * unsets @last_applied when each regions walking for applying the scheme is * finished. * - * After applying the &action to each region, &stat_count and &stat_sz is - * updated to reflect the number of regions and total size of regions that the - * &action is applied. + * After applying the &action to each region, &stat is updated. */ struct damos { struct damos_access_pattern pattern; -- cgit v1.2.3 From 84e425c68e6061751adecd2d328789e4f67eac1e Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Tue, 16 Dec 2025 00:01:20 -0800 Subject: mm/damon/core: implement max_nr_snapshots There are DAMOS use cases that require user-space centric control of its activation and deactivation. Having the control plane on the user-space, or using DAMOS as a way for monitoring results collection are such examples. DAMON parameters online commit, DAMOS quotas and watermarks can be useful for this purpose. However, those features work only at the sub-DAMON-snapshot level. In some use cases, the DAMON-snapshot level control is required. For example, in DAMOS-based monitoring results collection use case, the user online-installs a DAMOS scheme with DAMOS_STAT action, wait it be applied to whole regions of a single DAMON-snapshot, retrieves the stats and tried regions information, and online-uninstall the scheme. It is efficient to ensure the lifetime of the scheme as no more no less one snapshot consumption. To support such use cases, introduce a new DAMOS core API per-scheme parameter, namely max_nr_snapshots. As the name implies, it is the upper limit of nr_snapshots, which is a DAMOS stat that represents the number of DAMON-snapshots that the scheme has fully applied. If the limit is set with a non-zero value and nr_snapshots reaches or exceeds the limit, the scheme is deactivated. Link: https://lkml.kernel.org/r/20251216080128.42991-8-sj@kernel.org Signed-off-by: SeongJae Park Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers Cc: Michal Hocko Cc: Mike Rapoport Cc: Steven Rostedt Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/damon.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 43dfbfe2292f..a67292a2f09d 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -499,6 +499,7 @@ struct damos_migrate_dests { * @ops_filters: ops layer handling &struct damos_filter objects list. * @last_applied: Last @action applied ops-managing entity. * @stat: Statistics of this scheme. + * @max_nr_snapshots: Upper limit of nr_snapshots stat. * @list: List head for siblings. * * For each @apply_interval_us, DAMON finds regions which fit in the @@ -533,6 +534,9 @@ struct damos_migrate_dests { * finished. * * After applying the &action to each region, &stat is updated. + * + * If &max_nr_snapshots is set as non-zero and &stat.nr_snapshots be same to or + * greater than it, the scheme is deactivated. */ struct damos { struct damos_access_pattern pattern; @@ -567,6 +571,7 @@ struct damos { struct list_head ops_filters; void *last_applied; struct damos_stat stat; + unsigned long max_nr_snapshots; struct list_head list; }; -- cgit v1.2.3 From 5866891a7ab1348686da70f70e925964d9227bf5 Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Thu, 25 Dec 2025 15:21:13 -0800 Subject: mm/damon: use cgroup ID instead of private memcg ID DAMON was using the internal private memcg ID which is meant for tracking kernel objects that outlive their cgroup. Switch to using the public cgroup ID instead. Link: https://lkml.kernel.org/r/20251225232116.294540-6-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt Reviewed-by: SeongJae Park Acked-by: Michal Hocko Cc: Axel Rasmussen Cc: Dave Chinner Cc: David Hildenbrand Cc: Johannes Weiner Cc: Lorenzo Stoakes Cc: Muchun Song Cc: Qi Zheng Cc: Roman Gushchin Cc: Wei Xu Cc: Yuanchu Xie Signed-off-by: Andrew Morton --- include/linux/damon.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index a67292a2f09d..650e7ecfa32b 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -203,7 +203,7 @@ struct damos_quota_goal { u64 last_psi_total; struct { int nid; - unsigned short memcg_id; + u64 memcg_id; }; }; struct list_head list; @@ -419,7 +419,7 @@ struct damos_filter { bool matching; bool allow; union { - unsigned short memcg_id; + u64 memcg_id; struct damon_addr_range addr_range; int target_idx; struct damon_size_range sz_range; -- cgit v1.2.3 From 4835e2871321fd9cf5bc9702dded323e3e3fbc1a Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Tue, 13 Jan 2026 07:27:06 -0800 Subject: mm/damon/core: introduce [in]active memory ratio damos quota goal metric Patch series "mm/damon: advance DAMOS-based LRU sorting". DAMOS_LRU_[DE]PRIO actions were added to DAMOS for more access-aware LRU lists sorting. For simple usage, a specialized kernel module, namely DAMON_LRU_SORT, has also been introduced. After the introduction of the module, DAMON got a few important new features, including the aim-based quota auto-tuning, age tracking, young page filter, and monitoring intervals auto-tuning. Meanwhile, DAMOS-based LRU sorting had no direct updates. Now we show some rooms to advance for DAMOS-based LRU sorting. Firstly, the aim-oriented quota auto-tuning can simplify the LRU sorting parameters tuning. But there is no good auto-tuning target metric for LRU sorting use case. Secondly, the behavior of DAMOS_LRU_[DE]PRIO are not very symmetric. DAMOS_LRU_DEPRIO directly moves the pages to inactive LRU list, while DAMOS_LRU_PRIO only marks the page as accessed, so that the page can not directly but only eventually moved to the active LRU list. Finally, DAMON_LRU_SORT users cannot utilize the modern features that can be useful for them, too. Improve the situation with the following changes. First, introduce a new DAMOS quota auto-tuning target metric for active:inactive memory size ratio. Since LRU sorting is a kind of balancing of active and inactive pages, the active:inactive memory size ratio can be intuitively set. Second, update DAMOS_LRU_[DE]PRIO behaviors to be more intuitive and symmetric, by letting them directly move the pages to [in]active LRU list. Third, update the DAMON_LRU_SORT module user interface to be able to fully utilize the modern features including the [in]active memory size ratio-based quota auto-tuning, young page filter, and monitoring intervals auto-tuning. With these changes, for example, users can now ask DAMON to "find hot/cold memory regions with auto-tuned monitoring intervals, do one more page level access check for found hot/cold memory, and move pages of those to active or inactive LRU lists accordingly, aiming X:Y active to inactive memory ratio." For example, if they know 30% of the memory is better to be protected from reclamation, 30:70 can be set as the target ratio. Test Results ------------ I ran DAMON_LRU_SORT with the features introduced by this series, on a real world server workload. For the active:inactive ratio goal, I set 50:50. I confirmed it achieves the target active:inactive ratio, without manual tuning of the monitoring intervals and the hot/coldness thresholds. The baseline system that was not running the DAMON_LRU_SORT was keeping active:inactive ratio of about 1:10. Note that the test didn't show a clear performance difference, though. I believe that was mainly because the workload was not very memory intensive. Also, whether the 50:50 target ratio was optimum is unclear. Nonetheless, the positive performance impact of the basic LRU sorting idea is already confirmed with the initial DAMON_LRU_SORT introduction patch series. The goal of this patch series is simplifying the parameters tuning of DAMOS-based LRU sorting, and the test confirmed the aimed goals are achieved. Patches Sequence ---------------- First three patches extend DAMOS quota auto-tuning to support [in]active memory ratio target metric type. Those (patches 1-3) introduce new metrics, implement DAMON sysfs support, and update the documentation, respectively. Following patch (patch 4) makes DAMOS_LRU_PRIO action to directly move target pages to active LRU list, instead of only marking them accessed. Following seven patches (patches 5-11) updates DAMON_LRU_SORT to support modern DAMON features. Patch 5 makes it uses not only access frequency but also age at under-quota regions prioritization. Patches 6-11 add the support for young page filtering, active:inactive memory ratio based quota auto-tuning, and monitoring intervals auto-tuning, with appropriate document updates. This patch (of 11): DAMOS_LRU_[DE]PRIO are DAMOS actions for making balance of active and inactive memory size. There is no appropriate DAMOS quota auto-tuning target metric for the use case. Add two new DAMOS quota goal metrics for the purpose, namely DAMOS_QUOTA_[IN]ACTIVE_MEM_BP. Those will represent the ratio of [in]active memory to total (inactive + active) memory. Hence, users will be able to ask DAMON to, for example, "find hot and cold memory, and move pages of those to active and inactive LRU lists, adjusting the hot/cold thresholds aiming 50:50 active:inactive memory ratio." Link: https://lkml.kernel.org/r/20260113152717.70459-1-sj@kernel.org Link: https://lkml.kernel.org/r/20260113152717.70459-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- include/linux/damon.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 650e7ecfa32b..26fb8e90dff6 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -155,6 +155,8 @@ enum damos_action { * @DAMOS_QUOTA_NODE_MEM_FREE_BP: MemFree ratio of a node. * @DAMOS_QUOTA_NODE_MEMCG_USED_BP: MemUsed ratio of a node for a cgroup. * @DAMOS_QUOTA_NODE_MEMCG_FREE_BP: MemFree ratio of a node for a cgroup. + * @DAMOS_QUOTA_ACTIVE_MEM_BP: Active to total LRU memory ratio. + * @DAMOS_QUOTA_INACTIVE_MEM_BP: Inactive to total LRU memory ratio. * @NR_DAMOS_QUOTA_GOAL_METRICS: Number of DAMOS quota goal metrics. * * Metrics equal to larger than @NR_DAMOS_QUOTA_GOAL_METRICS are unsupported. @@ -166,6 +168,8 @@ enum damos_quota_goal_metric { DAMOS_QUOTA_NODE_MEM_FREE_BP, DAMOS_QUOTA_NODE_MEMCG_USED_BP, DAMOS_QUOTA_NODE_MEMCG_FREE_BP, + DAMOS_QUOTA_ACTIVE_MEM_BP, + DAMOS_QUOTA_INACTIVE_MEM_BP, NR_DAMOS_QUOTA_GOAL_METRICS, }; -- cgit v1.2.3 From 4262c53236977de3ceaa3bf2aefdf772c9b874dd Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Thu, 15 Jan 2026 07:20:41 -0800 Subject: mm/damon/core: implement damon_kdamond_pid() Patch series "mm/damon: hide kdamond and kdamond_lock from API callers". 'kdamond' and 'kdamond_lock' fields initially exposed to DAMON API callers for flexible synchronization and use cases. As DAMON API became somewhat complicated compared to the early days, Keeping those exposed could only encourage the API callers to invent more creative but complicated and difficult-to-debug use cases. Fortunately DAMON API callers didn't invent that many creative use cases. There exist only two use cases of 'kdamond' and 'kdamond_lock'. Finding whether the kdamond is actively running, and getting the pid of the kdamond. For the first use case, a dedicated API function, namely 'damon_is_running()' is provided, and all DAMON API callers are using the function for the use case. Hence only the second use case is where the fields are directly being used by DAMON API callers. To prevent future invention of complicated and erroneous use cases of the fields, hide the fields from the API callers. For that, provide new dedicated DAMON API functions for the remaining use case, namely damon_kdamond_pid(), migrate DAMON API callers to use the new function, and mark the fields as private fields. This patch (of 5): 'kdamond' and 'kdamond_lock' are directly being used by DAMON API callers for getting the pid of the corresponding kdamond. To discourage invention of creative but complicated and erroneous new usages of the fields that require careful synchronization, implement a new API function that can simply be used without the manual synchronizations. Link: https://lkml.kernel.org/r/20260115152047.68415-1-sj@kernel.org Link: https://lkml.kernel.org/r/20260115152047.68415-2-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 26fb8e90dff6..5b7ea7082134 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -972,6 +972,7 @@ bool damon_initialized(void); int damon_start(struct damon_ctx **ctxs, int nr_ctxs, bool exclusive); int damon_stop(struct damon_ctx **ctxs, int nr_ctxs); bool damon_is_running(struct damon_ctx *ctx); +int damon_kdamond_pid(struct damon_ctx *ctx); int damon_call(struct damon_ctx *ctx, struct damon_call_control *control); int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control); -- cgit v1.2.3 From 6fe0e6d599a6bb4b65704285d40d4972423b7aaa Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Thu, 15 Jan 2026 07:20:45 -0800 Subject: mm/damon: hide kdamond and kdamond_lock of damon_ctx There is no DAMON API caller that directly access 'kdamond' and 'kdamond_lock' fields of 'struct damon_ctx'. Keeping those exposed could only encourage creative but error-prone usages. Hide them from DAMON API callers by marking those as private fields. Link: https://lkml.kernel.org/r/20260115152047.68415-6-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 5b7ea7082134..e6930d8574d3 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -759,23 +759,20 @@ struct damon_attrs { * of the monitoring. * * @attrs: Monitoring attributes for accuracy/overhead control. - * @kdamond: Kernel thread who does the monitoring. - * @kdamond_lock: Mutex for the synchronizations with @kdamond. * - * For each monitoring context, one kernel thread for the monitoring is - * created. The pointer to the thread is stored in @kdamond. + * For each monitoring context, one kernel thread for the monitoring, namely + * kdamond, is created. The pid of kdamond can be retrieved using + * damon_kdamond_pid(). * - * Once started, the monitoring thread runs until explicitly required to be - * terminated or every monitoring target is invalid. The validity of the - * targets is checked via the &damon_operations.target_valid of @ops. The - * termination can also be explicitly requested by calling damon_stop(). - * The thread sets @kdamond to NULL when it terminates. Therefore, users can - * know whether the monitoring is ongoing or terminated by reading @kdamond. - * Reads and writes to @kdamond from outside of the monitoring thread must - * be protected by @kdamond_lock. + * Once started, kdamond runs until explicitly required to be terminated or + * every monitoring target is invalid. The validity of the targets is checked + * via the &damon_operations.target_valid of @ops. The termination can also be + * explicitly requested by calling damon_stop(). To know if a kdamond is + * running, damon_is_running() can be used. * - * Note that the monitoring thread protects only @kdamond via @kdamond_lock. - * Accesses to other fields must be protected by themselves. + * While the kdamond is running, all accesses to &struct damon_ctx from a + * thread other than the kdamond should be made using safe DAMON APIs, + * including damon_call() and damos_walk(). * * @ops: Set of monitoring operations for given use cases. * @addr_unit: Scale factor for core to ops address conversion. @@ -816,10 +813,12 @@ struct damon_ctx { struct damos_walk_control *walk_control; struct mutex walk_control_lock; -/* public: */ + /* Working thread of the given DAMON context */ struct task_struct *kdamond; + /* Protects @kdamond field access */ struct mutex kdamond_lock; +/* public: */ struct damon_operations ops; unsigned long addr_unit; unsigned long min_sz_region; -- cgit v1.2.3 From 50962b16c0d63725fa73f0a5b4b831f740cf7208 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 17 Jan 2026 09:52:48 -0800 Subject: mm/damon: remove damon_operations->cleanup() Patch series "mm/damon: cleanup kdamond, damon_call(), damos filter and DAMON_MIN_REGION". Do miscellaneous code cleanups for improving readability. First three patches cleanup kdamond termination process, by removing unused operation set cleanup callback (patch 1) and moving damon_ctx specific resource cleanups on kdamond termination to synchronization-easy place (patches 2 and 3). Next two patches touch damon_call() infrastructure, by refactoring kdamond_call() function to do less and simpler locking operations (patch 4), and documenting when dealloc_on_free does work (patch 5). Final three patches rename things for clear uses of those. Those rename damos_filter_out() to be more explicit about the fact that it is only for core-handled filters (patch 6), DAMON_MIN_REGION macro to be more explicit it is not about number of regions but size of each region (patch 7), and damon_ctx->min_sz_region to be different from damos_access_patern->min_sz_region (patch 8), so that those are not confusing and easy to grep. This patch (of 8): damon_operations->cleanup() was added for a case that an operation set implementation requires additional cleanups. But no such implementation exists at the moment. Remove it. Link: https://lkml.kernel.org/r/20260117175256.82826-1-sj@kernel.org Link: https://lkml.kernel.org/r/20260117175256.82826-2-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index e6930d8574d3..bd4c76b126bd 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -607,7 +607,6 @@ enum damon_ops_id { * @apply_scheme: Apply a DAMON-based operation scheme. * @target_valid: Determine if the target is valid. * @cleanup_target: Clean up each target before deallocation. - * @cleanup: Clean up the context. * * DAMON can be extended for various address spaces and usages. For this, * users should register the low level operations for their target address @@ -640,7 +639,6 @@ enum damon_ops_id { * @target_valid should check whether the target is still valid for the * monitoring. * @cleanup_target is called before the target will be deallocated. - * @cleanup is called from @kdamond just before its termination. */ struct damon_operations { enum damon_ops_id id; @@ -656,7 +654,6 @@ struct damon_operations { struct damos *scheme, unsigned long *sz_filter_passed); bool (*target_valid)(struct damon_target *t); void (*cleanup_target)(struct damon_target *t); - void (*cleanup)(struct damon_ctx *context); }; /* -- cgit v1.2.3 From 177c8a272968b6bcdbcc8589a72e3eaa32f975d0 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 17 Jan 2026 09:52:52 -0800 Subject: mm/damon: document damon_call_control->dealloc_on_cancel repeat behavior damon_call_control->dealloc_on_cancel works only when ->repeat is true. But the behavior is not clearly documented. DAMON API callers can understand the behavior only after reading kdamond_call() code. Document the behavior on the kernel-doc comment of damon_call_control. Link: https://lkml.kernel.org/r/20260117175256.82826-6-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index bd4c76b126bd..bdca28e15e40 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -663,7 +663,7 @@ struct damon_operations { * @data: Data that will be passed to @fn. * @repeat: Repeat invocations. * @return_code: Return code from @fn invocation. - * @dealloc_on_cancel: De-allocate when canceled. + * @dealloc_on_cancel: If @repeat is true, de-allocate when canceled. * * Control damon_call(), which requests specific kdamond to invoke a given * function. Refer to damon_call() for more details. -- cgit v1.2.3 From dfb1b0c9dc0d61e422905640e1e7334b3cf6f384 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 17 Jan 2026 09:52:54 -0800 Subject: mm/damon: rename DAMON_MIN_REGION to DAMON_MIN_REGION_SZ The macro is for the default minimum size of each DAMON region. There was a case that a reader was confused if it is the minimum number of total DAMON regions, which is set on damon_attrs->min_nr_regions. Make the name more explicit. Link: https://lkml.kernel.org/r/20260117175256.82826-8-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index bdca28e15e40..5bf8db1d78fe 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -15,7 +15,7 @@ #include /* Minimal region size. Every damon_region is aligned by this. */ -#define DAMON_MIN_REGION PAGE_SIZE +#define DAMON_MIN_REGION_SZ PAGE_SIZE /* Max priority score for DAMON-based operation schemes */ #define DAMOS_MAX_SCORE (99) -- cgit v1.2.3 From cc1db8dff8e751ec3ab352483de366b7f23aefe2 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sat, 17 Jan 2026 09:52:55 -0800 Subject: mm/damon: rename min_sz_region of damon_ctx to min_region_sz 'min_sz_region' field of 'struct damon_ctx' represents the minimum size of each DAMON region for the context. 'struct damos_access_pattern' has a field of the same name. It confuses readers and makes 'grep' less optimal for them. Rename it to 'min_region_sz'. Link: https://lkml.kernel.org/r/20260117175256.82826-9-sj@kernel.org Signed-off-by: SeongJae Park Signed-off-by: Andrew Morton --- include/linux/damon.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux/damon.h') diff --git a/include/linux/damon.h b/include/linux/damon.h index 5bf8db1d78fe..a4fea23da857 100644 --- a/include/linux/damon.h +++ b/include/linux/damon.h @@ -773,7 +773,7 @@ struct damon_attrs { * * @ops: Set of monitoring operations for given use cases. * @addr_unit: Scale factor for core to ops address conversion. - * @min_sz_region: Minimum region size. + * @min_region_sz: Minimum region size. * @adaptive_targets: Head of monitoring targets (&damon_target) list. * @schemes: Head of schemes (&damos) list. */ @@ -818,7 +818,7 @@ struct damon_ctx { /* public: */ struct damon_operations ops; unsigned long addr_unit; - unsigned long min_sz_region; + unsigned long min_region_sz; struct list_head adaptive_targets; struct list_head schemes; @@ -907,7 +907,7 @@ static inline void damon_insert_region(struct damon_region *r, void damon_add_region(struct damon_region *r, struct damon_target *t); void damon_destroy_region(struct damon_region *r, struct damon_target *t); int damon_set_regions(struct damon_target *t, struct damon_addr_range *ranges, - unsigned int nr_ranges, unsigned long min_sz_region); + unsigned int nr_ranges, unsigned long min_region_sz); void damon_update_region_access_rate(struct damon_region *r, bool accessed, struct damon_attrs *attrs); @@ -975,7 +975,7 @@ int damos_walk(struct damon_ctx *ctx, struct damos_walk_control *control); int damon_set_region_biggest_system_ram_default(struct damon_target *t, unsigned long *start, unsigned long *end, - unsigned long min_sz_region); + unsigned long min_region_sz); #endif /* CONFIG_DAMON */ -- cgit v1.2.3