linux-stable.git/samples/damon, branch linux-6.16.y

samples/damon/prcl: avoid starting DAMON before initialization

2025-09-25T09:16:54+00:00

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 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

samples/damon/mtier: avoid starting DAMON before initialization

2025-09-25T09:16:54+00:00

[ 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 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

samples/damon: change enable parameters to enabled

2025-09-25T09:16:54+00:00

[ 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 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton 
Stable-dep-of: c62cff40481c ("samples/damon/mtier: avoid starting DAMON before initialization")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

samples/damon/prcl: fix boot time enable crash

2025-09-25T09:16:53+00:00

[ 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 
Signed-off-by: Andrew Morton 
Stable-dep-of: c62cff40481c ("samples/damon/mtier: avoid starting DAMON before initialization")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

samples/damon/mtier: support boot time enable setup

2025-08-20T16:41:35+00:00

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 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

samples/damon/wsse: fix boot time enable handling

2025-08-20T16:41:35+00:00

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 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

samples/damon: fix damon sample mtier for start failure

2025-07-10T04:07:55+00:00

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 
Reviewed-by: SeongJae Park 
Cc: 
Signed-off-by: Andrew Morton

samples/damon: fix damon sample wsse for start failure

2025-07-10T04:07:55+00:00

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 
Reviewed-by: SeongJae Park 
Cc: 
Signed-off-by: Andrew Morton

samples/damon: fix damon sample prcl for start failure

2025-07-10T04:07:54+00:00

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]  
  [ 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 
Reviewed-by: SeongJae Park 
Cc: 
Signed-off-by: Andrew Morton

samples/damon: implement a DAMON module for memory tiering

2025-05-13T06:50:30+00:00

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 
Cc: Jonathan Corbet 
Cc: Yunjeong Mun 
Signed-off-by: Andrew Morton