kernel/mm/damon/sysfs.c, branch linux-6.19.y

mm/damon: rename min_sz_region of damon_ctx to min_region_sz

2026-03-19T15:15:32Z

[ Upstream commit cc1db8dff8e751ec3ab352483de366b7f23aefe2 ] '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 Stable-dep-of: c80f46ac228b ("mm/damon/core: disallow non-power of two min_region_sz") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm/damon: rename DAMON_MIN_REGION to DAMON_MIN_REGION_SZ

2026-03-19T15:15:32Z

[ Upstream commit dfb1b0c9dc0d61e422905640e1e7334b3cf6f384 ] 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 Stable-dep-of: c80f46ac228b ("mm/damon/core: disallow non-power of two min_region_sz") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm/damon/sysfs: cleanup attrs subdirs on context dir setup failure

2026-01-15T06:16:23Z

When a context DAMON sysfs directory setup is failed after setup of attrs/ directory, subdirectories of attrs/ directory are not cleaned up. As a result, DAMON sysfs interface is nearly broken until the system reboots, and the memory for the unremoved directory is leaked. Cleanup the directories under such failures. Link: https://lkml.kernel.org/r/20251225023043.18579-3-sj@kernel.org Fixes: c951cd3b8901 ("mm/damon: implement a minimal stub for sysfs-based DAMON interface") Signed-off-by: SeongJae Park Cc: chongjiapeng Cc: # 5.18.x Signed-off-by: Andrew Morton

mm/damon/sysfs: cleanup intervals subdirs on attrs dir setup failure

2026-01-15T06:16:23Z

Patch series "mm/damon/sysfs: free setup failures generated zombie sub-sub dirs". Some DAMON sysfs directory setup functions generates its sub and sub-sub directories. For example, 'monitoring_attrs/' directory setup creates 'intervals/' and 'intervals/intervals_goal/' directories under 'monitoring_attrs/' directory. When such sub-sub directories are successfully made but followup setup is failed, the setup function should recursively clean up the subdirectories. However, such setup functions are only dereferencing sub directory reference counters. As a result, under certain setup failures, the sub-sub directories keep having non-zero reference counters. It means the directories cannot be removed like zombies, and the memory for the directories cannot be freed. The user impact of this issue is limited due to the following reasons. When the issue happens, the zombie directories are still taking the path. Hence attempts to generate the directories again will fail, without additional memory leak. This means the upper bound memory leak is limited. Nonetheless this also implies controlling DAMON with a feature that requires the setup-failed sysfs files will be impossible until the system reboots. Also, the setup operations are quite simple. The certain failures would hence only rarely happen, and are difficult to artificially trigger. This patch (of 4): When attrs/ DAMON sysfs directory setup is failed after setup of intervals/ directory, intervals/intervals_goal/ directory is not cleaned up. As a result, DAMON sysfs interface is nearly broken until the system reboots, and the memory for the unremoved directory is leaked. Cleanup the directory under such failures. Link: https://lkml.kernel.org/r/20251225023043.18579-1-sj@kernel.org Link: https://lkml.kernel.org/r/20251225023043.18579-2-sj@kernel.org Fixes: 8fbbcbeaafeb ("mm/damon/sysfs: implement intervals tuning goal directory") Signed-off-by: SeongJae Park Cc: chongjiapeng Cc: # 6.15.x Signed-off-by: Andrew Morton

mm/damon/sysfs: implement obsolete_target file

2025-11-17T01:28:23Z

There is no good way to remove DAMON targets in the middle of the existing targets list. It restricts efficient and flexible DAMON use cases. Improve the usability by implementing a new DAMON sysfs interface file, namely obsolete_target, under each target directory. It is connected to the obsolete field of parameters commit-source targets, so allows removing arbitrary targets in the middle of existing targets list. Note that the sysfs files are not automatically updated. For example, let's suppose there are three targets in the running context, and a user removes the third target using this feature. If the user writes 'commit' to the kdamond 'state' file again, DAMON sysfs interface will again try to remove the third target. But because there is no matching target in the running context, the commit will fail. It is the user's responsibility to understand resulting DAMON internal targets list change, and construct sysfs files (using nr_targets and other sysfs files) to correctly represent it. Also note that this is arguably an improvement rather than a fix of broken things. Link: https://lkml.kernel.org/r/20251023012535.69625-4-sj@kernel.org Signed-off-by: SeongJae Park Reported-by: Bijan Tabatabai Closes: https://github.com/damonitor/damo/issues/36 Reviewed-by: Bijan Tabatabai Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm/damon/sysfs: test commit input against realistic destination

2025-11-17T01:28:23Z

DAMON sysfs interface tests if given online parameters update request is valid, by committing those using the DAMON kernel API, to a test-purpose destination context. The test-purpose destination context is constructed using damon_new_ctx(), so it has no target, no scheme. If a source target has the obsolete field set, the test-purpose commit will fail because damon_commit_targets() fails when there is a source obsolete target that cannot find its matching destination target. DAMON sysfs interface is not letting users set the field for now, so there is no problem. However, the following commit will support that. Also there could be similar future changes that making commit fails based on current context structure. Make the test purpose commit destination context similar to the current running one, by committing the running one to the test purpose context, before doing the real test-purpose commit. Link: https://lkml.kernel.org/r/20251023012535.69625-3-sj@kernel.org Signed-off-by: SeongJae Park Reviewed-by: Bijan Tabatabai Cc: David Hildenbrand Cc: Jonathan Corbet Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Michal Hocko Cc: Mike Rapoport Cc: Shuah Khan Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton

mm: fix some typos in mm module

2025-11-17T01:27:52Z

Below are some typos in the code comments: intevals ==> intervals addesses ==> addresses unavaliable ==> unavailable facor ==> factor droping ==> dropping exlusive ==> exclusive decription ==> description confict ==> conflict desriptions ==> descriptions otherwize ==> otherwise vlaue ==> value cheching ==> checking exisitng ==> existing modifed ==> modified differenciate ==> differentiate refernece ==> reference permissons ==> permissions indepdenent ==> independent spliting ==> splitting Just fix it. Link: https://lkml.kernel.org/r/20250929002608.1633825-1-jianyungao89@gmail.com Signed-off-by: jianyun.gao Reviewed-by: SeongJae Park Reviewed-by: Wei Yang Reviewed-by: Dev Jain Reviewed-by: Liam R. Howlett Acked-by: Chris Li Signed-off-by: Andrew Morton

mm/damon/sysfs: change next_update_jiffies to a global variable

2025-11-10T05:19:45Z

In DAMON's damon_sysfs_repeat_call_fn(), time_before() is used to compare the current jiffies with next_update_jiffies to determine whether to update the sysfs files at this moment. On 32-bit systems, the kernel initializes jiffies to "-5 minutes" to make jiffies wrap bugs appear earlier. However, this causes time_before() in damon_sysfs_repeat_call_fn() to unexpectedly return true during the first 5 minutes after boot on 32-bit systems (see [1] for more explanation, which fixes another jiffies-related issue before). As a result, DAMON does not update sysfs files during that period. There is also an issue unrelated to the system's word size[2]: if the user stops DAMON just after next_update_jiffies is updated and restarts it after 'refresh_ms' or a longer delay, next_update_jiffies will retain an older value, causing time_before() to return false and the update to happen earlier than expected. Fix these issues by making next_update_jiffies a global variable and initializing it each time DAMON is started. Link: https://lkml.kernel.org/r/20251030020746.967174-3-yanquanmin1@huawei.com Link: https://lkml.kernel.org/r/20250822025057.1740854-1-ekffu200098@gmail.com [1] Link: https://lore.kernel.org/all/20251029013038.66625-1-sj@kernel.org/ [2] Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work") Suggested-by: SeongJae Park Reviewed-by: SeongJae Park Signed-off-by: Quanmin Yan Cc: Kefeng Wang Cc: ze zuo Cc: Signed-off-by: Andrew Morton

mm/damon/sysfs: dealloc commit test ctx always

2025-10-15T20:24:33Z

The damon_ctx for testing online DAMON parameters commit inputs is deallocated only when the test fails. This means memory is leaked for every successful online DAMON parameters commit. Fix the leak by always deallocating it. Link: https://lkml.kernel.org/r/20251003201455.41448-3-sj@kernel.org Fixes: 4c9ea539ad59 ("mm/damon/sysfs: validate user inputs from damon_sysfs_commit_input()") Signed-off-by: SeongJae Park Cc: [6.15+] Signed-off-by: Andrew Morton

mm/damon/sysfs: catch commit test ctx alloc failure

2025-10-15T20:24:33Z

Patch series "mm/damon/sysfs: fix commit test damon_ctx [de]allocation". DAMON sysfs interface dynamically allocates and uses a damon_ctx object for testing if given inputs for online DAMON parameters update is valid. The object is being used without an allocation failure check, and leaked when the test succeeds. Fix the two bugs. This patch (of 2): The damon_ctx for testing online DAMON parameters commit inputs is used without its allocation failure check. This could result in an invalid memory access. Fix it by directly returning an error when the allocation failed. Link: https://lkml.kernel.org/r/20251003201455.41448-1-sj@kernel.org Link: https://lkml.kernel.org/r/20251003201455.41448-2-sj@kernel.org Fixes: 4c9ea539ad59 ("mm/damon/sysfs: validate user inputs from damon_sysfs_commit_input()") Signed-off-by: SeongJae Park Cc: [6.15+] Signed-off-by: Andrew Morton