kernel.git/mm/damon, branch linux-rolling-lts

mm/damon/core: disallow non-power of two min_region_sz

2026-03-19T15:08:51Z

[ Upstream commit c80f46ac228b48403866d65391ad09bdf0e8562a ] DAMON core uses min_region_sz parameter value as the DAMON region alignment. The alignment is made using ALIGN() and ALIGN_DOWN(), which support only the power of two alignments. But DAMON core API callers can set min_region_sz to an arbitrary number. Users can also set it indirectly, using addr_unit. When the alignment is not properly set, DAMON behavior becomes difficult to expect and understand, makes it effectively broken. It doesn't cause a kernel crash-like significant issue, though. Fix the issue by disallowing min_region_sz input that is not a power of two. Add the check to damon_commit_ctx(), as all DAMON API callers who set min_region_sz uses the function. This can be a sort of behavioral change, but it does not break users, for the following reasons. As the symptom is making DAMON effectively broken, it is not reasonable to believe there are real use cases of non-power of two min_region_sz. There is no known use case or issue reports from the setup, either. In future, if we find real use cases of non-power of two alignments and we can support it with low enough overhead, we can consider moving the restriction. But, for now, simply disallowing the corner case should be good enough as a hot fix. Link: https://lkml.kernel.org/r/20260214214124.87689-1-sj@kernel.org Fixes: d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region") Signed-off-by: SeongJae Park Cc: Quanmin Yan Cc: [6.18+] Signed-off-by: Andrew Morton [ min_region_sz => min_sz_region ] Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm/damon/core: clear walk_control on inactive context in damos_walk()

2026-03-19T15:08:35Z

commit d210fdcac9c0d1380eab448aebc93f602c1cd4e6 upstream. damos_walk() sets ctx->walk_control to the caller-provided control structure before checking whether the context is running. If the context is inactive (damon_is_running() returns false), the function returns -EINVAL without clearing ctx->walk_control. This leaves a dangling pointer to a stack-allocated structure that will be freed when the caller returns. This is structurally identical to the bug fixed in commit f9132fbc2e83 ("mm/damon/core: remove call_control in inactive contexts") for damon_call(), which had the same pattern of linking a control object and returning an error without unlinking it. The dangling walk_control pointer can cause: 1. Use-after-free if the context is later started and kdamond dereferences ctx->walk_control (e.g., in damos_walk_cancel() which writes to control->canceled and calls complete()) 2. Permanent -EBUSY from subsequent damos_walk() calls, since the stale pointer is non-NULL Nonetheless, the real user impact is quite restrictive. The use-after-free is impossible because there is no damos_walk() callers who starts the context later. The permanent -EBUSY can actually confuse users, as DAMON is not running. But the symptom is kept only while the context is turned off. Turning it on again will make DAMON internally uses a newly generated damon_ctx object that doesn't have the invalid damos_walk_control pointer, so everything will work fine again. Fix this by clearing ctx->walk_control under walk_control_lock before returning -EINVAL, mirroring the fix pattern from f9132fbc2e83. Link: https://lkml.kernel.org/r/20260224011102.56033-1-sj@kernel.org Fixes: bf0eaba0ff9c ("mm/damon/core: implement damos_walk()") Reported-by: Raul Pazemecxas De Andrade Closes: https://lore.kernel.org/CPUPR80MB8171025468965E583EF2490F956CA@CPUPR80MB8171.lamprd80.prod.outlook.com Signed-off-by: Raul Pazemecxas De Andrade Signed-off-by: SeongJae Park Reviewed-by: SeongJae Park Cc: [6.14+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: fix some typos in mm module

2026-01-30T09:32:28Z

[ Upstream commit b6c46600bfb28b4be4e9cff7bad4f2cf357e0fb7 ] 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 Stable-dep-of: 3937027caecb ("mm/hugetlb: fix two comments related to huge_pmd_unshare()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

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

2026-01-23T10:21:30Z

commit 9814cc832b88bd040fc2a1817c2b5469d0f7e862 upstream. 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 Signed-off-by: Greg Kroah-Hartman

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

2026-01-23T10:21:30Z

commit a24ca8ebb0cd5ea07a1462b77be0f0823c40f319 upstream. 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 Signed-off-by: Greg Kroah-Hartman

mm/damon/sysfs-scheme: cleanup access_pattern subdirs on scheme dir setup failure

2026-01-23T10:21:30Z

commit 392b3d9d595f34877dd745b470c711e8ebcd225c upstream. When a DAMOS-scheme DAMON sysfs directory setup fails after setup of access_pattern/ directory, subdirectories of access_pattern/ 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/20251225023043.18579-5-sj@kernel.org Fixes: 9bbb820a5bd5 ("mm/damon/sysfs: support DAMOS quotas") Signed-off-by: SeongJae Park Cc: chongjiapeng Cc: # 5.18.x Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/damon/sysfs-scheme: cleanup quotas subdirs on scheme dir setup failure

2026-01-23T10:21:30Z

commit dc7e1d75fd8c505096d0cddeca9e2efb2b55aaf9 upstream. When a DAMOS-scheme DAMON sysfs directory setup fails after setup of quotas/ directory, subdirectories of quotas/ 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/20251225023043.18579-4-sj@kernel.org Fixes: 1b32234ab087 ("mm/damon/sysfs: support DAMOS watermarks") Signed-off-by: SeongJae Park Cc: chongjiapeng Cc: # 5.18.x Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/damon/core: remove call_control in inactive contexts

2026-01-23T10:21:29Z

commit f9132fbc2e83baf2c45a77043672a63a675c9394 upstream. If damon_call() is executed against a DAMON context that is not running, the function returns error while keeping the damon_call_control object linked to the context's call_controls list. Let's suppose the object is deallocated after the damon_call(), and yet another damon_call() is executed against the same context. The function tries to add the new damon_call_control object to the call_controls list, which still has the pointer to the previous damon_call_control object, which is deallocated. As a result, use-after-free happens. This can actually be triggered using the DAMON sysfs interface. It is not easily exploitable since it requires the sysfs write permission and making a definitely weird file writes, though. Please refer to the report for more details about the issue reproduction steps. Fix the issue by making two changes. Firstly, move the final kdamond_call() for cancelling all existing damon_call() requests from terminating DAMON context to be done before the ctx->kdamond reset. This makes any code that sees NULL ctx->kdamond can safely assume the context may not access damon_call() requests anymore. Secondly, let damon_call() to cleanup the damon_call_control objects that were added to the already-terminated DAMON context, before returning the error. Link: https://lkml.kernel.org/r/20251231012315.75835-1-sj@kernel.org Fixes: 004ded6bee11 ("mm/damon: accept parallel damon_call() requests") Signed-off-by: SeongJae Park Reported-by: JaeJoon Jung Closes: https://lore.kernel.org/20251224094401.20384-1-rgbi3307@gmail.com Cc: # 6.17.x Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm/damon/tests/core-kunit: handle alloc failures on damon_test_split_regions_of()

2026-01-08T09:17:21Z

damon_test_split_regions_of() is assuming all dynamic memory allocation in it will succeed. Those are indeed likely in the real use cases since those allocations are too small to fail, but theoretically those could fail. In the case, inappropriate memory access can happen. Fix it by appropriately cleanup pre-allocated memory and skip the execution of the remaining tests in the failure cases. Link: https://lkml.kernel.org/r/20251101182021.74868-9-sj@kernel.org Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests") Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: David Gow Cc: Kefeng Wang Cc: [5.15+] Signed-off-by: Andrew Morton (cherry picked from commit eded254cb69044bd4abde87394ea44909708d7c0) Signed-off-by: SeongJae Park Signed-off-by: Greg Kroah-Hartman

mm/damon/tests/core-kunit: handle alloc failure on damos_test_commit_filter()

2026-01-08T09:17:08Z

commit 3e5c4a1a1737bd79abaaa184233d0f815e62273b upstream. damon_test_commit_filter() is assuming all dynamic memory allocation in it will succeed. Those are indeed likely in the real use cases since those allocations are too small to fail, but theoretically those could fail. In the case, inappropriate memory access can happen. Fix it by appropriately cleanup pre-allocated memory and skip the execution of the remaining tests in the failure cases. Link: https://lkml.kernel.org/r/20251101182021.74868-15-sj@kernel.org Fixes: f6a4a150f1ec ("mm/damon/tests/core-kunit: add damos_commit_filter test") Signed-off-by: SeongJae Park Cc: Brendan Higgins Cc: David Gow Cc: Kefeng Wang Cc: [6.18+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman