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2025-09-25samples/damon/prcl: avoid starting DAMON before initializationSeongJae Park
commit e6b733ca2f99e968d696c2e812c8eb8e090bf37b upstream. Commit 2780505ec2b4 ("samples/damon/prcl: fix boot time enable crash") is somehow incompletely applying the origin patch [1]. It is missing the part that avoids starting DAMON before module initialization. Probably a mistake during a merge has happened. Fix it by applying the missed part again. Link: https://lkml.kernel.org/r/20250909022238.2989-3-sj@kernel.org Link: https://lore.kernel.org/20250706193207.39810-3-sj@kernel.org [1] Fixes: 2780505ec2b4 ("samples/damon/prcl: fix boot time enable crash") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-25samples/damon/mtier: avoid starting DAMON before initializationSeongJae Park
[ Upstream commit c62cff40481c037307a13becbda795f7afdcfebd ] Commit 964314344eab ("samples/damon/mtier: support boot time enable setup") is somehow incompletely applying the origin patch [1]. It is missing the part that avoids starting DAMON before module initialization. Probably a mistake during a merge has happened. Fix it by applying the missed part again. Link: https://lkml.kernel.org/r/20250909022238.2989-4-sj@kernel.org Link: https://lore.kernel.org/20250706193207.39810-4-sj@kernel.org [1] Fixes: 964314344eab ("samples/damon/mtier: support boot time enable setup") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-25samples/damon: change enable parameters to enabledHonggyu Kim
[ Upstream commit 793020545cea0c9e2a79de6ad5c9746ec4f5bd7e ] The damon_{lru_sort,reclaim,stat} kernel modules use "enabled" parameter knobs as follows. /sys/module/damon_lru_sort/parameters/enabled /sys/module/damon_reclaim/parameters/enabled /sys/module/damon_stat/parameters/enabled However, other sample modules of damon use "enable" parameter knobs so it'd be better to rename them from "enable" to "enabled" to keep the consistency with other damon modules. Before: /sys/module/damon_sample_wsse/parameters/enable /sys/module/damon_sample_prcl/parameters/enable /sys/module/damon_sample_mtier/parameters/enable After: /sys/module/damon_sample_wsse/parameters/enabled /sys/module/damon_sample_prcl/parameters/enabled /sys/module/damon_sample_mtier/parameters/enabled There is no functional changes in this patch. Link: https://lkml.kernel.org/r/20250707024548.1964-1-honggyu.kim@sk.com Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: c62cff40481c ("samples/damon/mtier: avoid starting DAMON before initialization") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-25samples/damon/prcl: fix boot time enable crashSeongJae Park
[ Upstream commit 2780505ec2b42c07853b34640bc63279ac2bb53b ] If 'enable' parameter of the 'prcl' DAMON sample module is set at boot time via the kernel command line, memory allocation is tried before the slab is initialized. As a result kernel NULL pointer dereference BUG can happen. Fix it by checking the initialization status. Link: https://lkml.kernel.org/r/20250706193207.39810-3-sj@kernel.org Fixes: 2aca254620a8 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation") Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: c62cff40481c ("samples/damon/mtier: avoid starting DAMON before initialization") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-08-20samples/damon/mtier: support boot time enable setupSeongJae Park
commit 964314344eab7bc43e38a32be281c5ea0609773b upstream. If 'enable' parameter of the 'mtier' DAMON sample module is set at boot time via the kernel command line, memory allocation is tried before the slab is initialized. As a result kernel NULL pointer dereference BUG can happen. Fix it by checking the initialization status. Link: https://lkml.kernel.org/r/20250706193207.39810-4-sj@kernel.org Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-08-20samples/damon/wsse: fix boot time enable handlingSeongJae Park
commit 0ed1165c37277822b519f519d0982d36efc30006 upstream. Patch series "mm/damon: fix misc bugs in DAMON modules". From manual code review, I found below bugs in DAMON modules. DAMON sample modules crash if those are enabled at boot time, via kernel command line. A similar issue was found and fixed on DAMON non-sample modules in the past, but we didn't check that for sample modules. DAMON non-sample modules are not setting 'enabled' parameters accordingly when real enabling is failed. Honggyu found and fixed[1] this type of bugs in DAMON sample modules, and my inspection was motivated by the great work. Kudos to Honggyu. Finally, DAMON_RECLIAM is mistakenly losing scheme internal status due to misuse of damon_commit_ctx(). DAMON_LRU_SORT has a similar misuse, but fortunately it is not causing real status loss. Fix the bugs. Since these are similar patterns of bugs that were found in the past, it would be better to add tests or refactor the code, in future. This patch (of 6): If 'enable' parameter of the 'wsse' DAMON sample module is set at boot time via the kernel command line, memory allocation is tried before the slab is initialized. As a result kernel NULL pointer dereference BUG can happen. Fix it by checking the initialization status. Link: https://lkml.kernel.org/r/20250706193207.39810-1-sj@kernel.org Link: https://lkml.kernel.org/r/20250706193207.39810-2-sj@kernel.org Link: https://lore.kernel.org/20250702000205.1921-1-honggyu.kim@sk.com [1] Fixes: b757c6cfc696 ("samples/damon/wsse: start and stop DAMON as the user requests") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-09samples/damon: fix damon sample mtier for start failureHonggyu Kim
The damon_sample_mtier_start() can fail so we must reset the "enable" parameter to "false" again for proper rollback. In such cases, setting Y to "enable" then N triggers the similar crash with mtier because damon sample start failed but the "enable" stays as Y. Link: https://lkml.kernel.org/r/20250702000205.1921-4-honggyu.kim@sk.com Fixes: 82a08bde3cf7 ("samples/damon: implement a DAMON module for memory tiering") Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09samples/damon: fix damon sample wsse for start failureHonggyu Kim
The damon_sample_wsse_start() can fail so we must reset the "enable" parameter to "false" again for proper rollback. In such cases, setting Y to "enable" then N triggers the similar crash with wsse because damon sample start failed but the "enable" stays as Y. Link: https://lkml.kernel.org/r/20250702000205.1921-3-honggyu.kim@sk.com Fixes: b757c6cfc696 ("samples/damon/wsse: start and stop DAMON as the user requests") Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-09samples/damon: fix damon sample prcl for start failureHonggyu Kim
Patch series "mm/damon: fix divide by zero and its samples", v3. This series includes fixes against damon and its samples to make it safer when damon sample starting fails. It includes the following changes. - fix unexpected divide by zero crash for zero size regions - fix bugs for damon samples in case of start failures This patch (of 4): The damon_sample_prcl_start() can fail so we must reset the "enable" parameter to "false" again for proper rollback. In such cases, setting Y to "enable" then N triggers the following crash because damon sample start failed but the "enable" stays as Y. [ 2441.419649] damon_sample_prcl: start [ 2454.146817] damon_sample_prcl: stop [ 2454.146862] ------------[ cut here ]------------ [ 2454.146865] kernel BUG at mm/slub.c:546! [ 2454.148183] Oops: invalid opcode: 0000 [#1] SMP NOPTI ... [ 2454.167555] Call Trace: [ 2454.167822] <TASK> [ 2454.168061] damon_destroy_ctx+0x78/0x140 [ 2454.168454] damon_sample_prcl_enable_store+0x8d/0xd0 [ 2454.168932] param_attr_store+0xa1/0x120 [ 2454.169315] module_attr_store+0x20/0x50 [ 2454.169695] sysfs_kf_write+0x72/0x90 [ 2454.170065] kernfs_fop_write_iter+0x150/0x1e0 [ 2454.170491] vfs_write+0x315/0x440 [ 2454.170833] ksys_write+0x69/0xf0 [ 2454.171162] __x64_sys_write+0x19/0x30 [ 2454.171525] x64_sys_call+0x18b2/0x2700 [ 2454.171900] do_syscall_64+0x7f/0x680 [ 2454.172258] ? exit_to_user_mode_loop+0xf6/0x180 [ 2454.172694] ? clear_bhb_loop+0x30/0x80 [ 2454.173067] ? clear_bhb_loop+0x30/0x80 [ 2454.173439] entry_SYSCALL_64_after_hwframe+0x76/0x7e Link: https://lkml.kernel.org/r/20250702000205.1921-1-honggyu.kim@sk.com Link: https://lkml.kernel.org/r/20250702000205.1921-2-honggyu.kim@sk.com Fixes: 2aca254620a8 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation") Signed-off-by: Honggyu Kim <honggyu.kim@sk.com> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12samples/damon: implement a DAMON module for memory tieringSeongJae Park
Implement a sample DAMON module that shows how self-tuned DAMON-based memory tiering can be written. It is a sample since the purpose is to give an idea about how it can be implemented and perform, rather than be used on general production setups. Especially, it supports only two tiers memory setup having only one CPU-attached NUMA node. [sj@kernel.org: fix wrong DAMON attrs setting] Link: https://lkml.kernel.org/r/20250510220932.47722-1-sj@kernel.org [sj@kernel.org: trigger build even if only mtier is enabled] Link: https://lkml.kernel.org/r/20250426184054.11437-1-sj@kernel.org Link: https://lkml.kernel.org/r/20250420194030.75838-8-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Yunjeong Mun <yunjeong.mun@sk.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-11samples/damon/prcl: fix a comment typoEnze Li
This patch just fixes a typo in the comment. Link: https://lkml.kernel.org/r/20250411073800.1444481-1-lienze@kylinos.cn Signed-off-by: Enze Li <lienze@kylinos.cn> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-03-17samples/damon: a typo in the kconfig - samepleSeongjun Kim
There is a typo in the Kconfig file of the damon sample module. Correct it: s/sameple/sample/ Link: https://lkml.kernel.org/r/20250226184204.29370-1-sj@kernel.org Signed-off-by: Seongjun Kim <bus710@gmail.com> Signed-off-by: SeongJae Park <sj@kernel.org> Reviewed-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13samples/damon/prcl: implement schemes setupSeongJae Park
Implement a proactive cold memory regions reclaiming logic of prcl sample module using DAMOS. The logic treats memory regions that not accessed at all for five or more seconds as cold, and reclaim those as soon as found. Link: https://lkml.kernel.org/r/20241210215030.85675-6-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13samples/damon: introduce a skeleton of a smaple DAMON module for proactive ↵SeongJae Park
reclamation DAMON is not only for monitoring of access patterns, but also for access-aware system operations. For the system operations, DAMON provides a feature called DAMOS (Data Access Monitoring-based Operation Schemes). There is no sample API usage of DAMOS, though. Copy the working set size estimation sample modules with changed names of the module and symbols, to use it as a skeleton for a sample module showing the DAMOS API usage. The following commit will make it proactively reclaim cold memory of the given process, using DAMOS. Link: https://lkml.kernel.org/r/20241210215030.85675-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13samples/damon/wsse: implement working set size estimation and loggingSeongJae Park
Implement the DAMON-based working set size estimation logic. The logic iterates memory regions in DAMON-generated access pattern snapshot for every aggregation interval and get the total sum of the size of any region having one or higher 'nr_accesses' count. That is, it assumes any region having one or higher 'nr_accesses' to be a part of the working set. The estimated value is reported to the user by printing it to the kernel log. Link: https://lkml.kernel.org/r/20241210215030.85675-4-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13samples/damon/wsse: start and stop DAMON as the user requestsSeongJae Park
Start running DAMON to monitor accesses of a process that the user specified via 'target_pid' parameter, when 'y' is passed to 'enable' parameter. Stop running DAMON when 'n' is passed to 'enable' parameter. Estimating the working set size from DAMON's monitoring results and reporting it to the user will be implemented by the following commit. Link: https://lkml.kernel.org/r/20241210215030.85675-3-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-01-13samples: add a skeleton of a sample DAMON module for working set size estimationSeongJae Park
Patch series "mm/damon: add sample modules". Implement a proactive cold memory regions reclaiming logic of prcl sample module using DAMOS. The logic treats memory regions that not accessed at all for five or more seconds as cold, and reclaim those as soon as found. This patch (of 5): Add a skeleton for a sample DAMON static module that can be used for estimating working set size of a given process. Note that it is a static module since DAMON is not exporting symbols to loadable modules for now. It exposes two module parameters, namely 'pid' and 'enable'. 'pid' will specify the process that the module will estimate the working set size of. 'enable' will receive whether to start or stop the estimation. Because this is just a skeleton, the parameters do nothing, though. The functionalities will be implemented by following commits. Link: https://lkml.kernel.org/r/20241210215030.85675-1-sj@kernel.org Link: https://lkml.kernel.org/r/20241210215030.85675-2-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>