The comment on top of `struct damon_region` clearly says that
For any use case, @ar should be non-zero positive size.
which is now verified in damon_verify_new_region() if the kernel is built
with DAMON_DEBUG_SANITY.
The WARN_ONCE() can be triggered if the mtier sample module is enabled
before node{0,1}_{start,end}_addr have been properly initialized, which is
obviously not good.
------------[ cut here ]------------
start 0 >= end 0
WARNING: mm/damon/core.c:217 at damon_new_region+0xf4/0x118, CPU#59: bash/341468
Call trace:
damon_new_region+0xf4/0x118 (P)
damon_set_regions+0xfc/0x3c0
damon_sample_mtier_build_ctx+0xe8/0x3a8
damon_sample_mtier_start+0x1c/0x90
damon_sample_mtier_enable_store+0x98/0xb0
param_attr_store+0xb4/0x128
module_attr_store+0x2c/0x50
sysfs_kf_write+0x58/0x90
kernfs_fop_write_iter+0x16c/0x238
vfs_write+0x2c0/0x370
ksys_write+0x74/0x118
__arm64_sys_write+0x24/0x38
invoke_syscall+0xa8/0x118
el0_svc_common.constprop.0+0x48/0xf0
do_el0_svc+0x24/0x38
el0_svc+0x54/0x370
el0t_64_sync_handler+0xa0/0xe8
el0t_64_sync+0x1ac/0x1b0
---[ end trace 0000000000000000 ]---
Note that the same issue can happen if detect_node_addresses is true, and
node 0 or 1 is memoryless. Fix it together by checking the validity of
parameters right before damon_new_region() and fail early if they're
invalid.
Link: https://lore.kernel.org/20260629144432.133962-1-sj@kernel.org
Fixes: 82a08bde3c ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: SJ Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mtier DAMON sample module and DAMON virtual address operation set (vaddr)
unit tests are using damon_add_region() for setup of DAMON monitoring
target region boundaries setup. But, damon_set_regions() is designed for
exactly the purpose. All other DAMON API callers use the function for the
purpose. Replace damon_add_region() usage in mtier sample module with
damon_set_regions(), for unifying the use case and reducing the
maintenance cost.
Link: https://lore.kernel.org/20260522154026.80546-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_mtier is assuming DAMON is ready to use in module_init time,
and uses its own hack to see if it is the time. Use damon_initialized(),
which is a way for seeing if DAMON is ready to be used that is more
reliable and better to maintain instead of the hack.
Link: https://lkml.kernel.org/r/20250916033511.116366-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_prcl is assuming DAMON is ready to use in module_init time,
and uses its own hack to see if it is the time. Use damon_initialized(),
which is a way for seeing if DAMON is ready to be used that is more
reliable and better to maintain instead of the hack.
Link: https://lkml.kernel.org/r/20250916033511.116366-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_wsse is assuming DAMON is ready to use in module_init time,
and uses its own hack to see if it is the time. Use damon_initialized(),
which is a way for seeing if DAMON is ready to be used that is more
reliable and better to maintain instead of the hack.
Link: https://lkml.kernel.org/r/20250916033511.116366-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "samples/damon: fix boot time enable handling fixup merge
mistakes".
First three patches of the patch series "mm/damon: fix misc bugs in DAMON
modules" [1] were trying to fix boot time DAMON sample modules enabling
issues. The issues are the modules can crash if those are enabled before
DAMON is enabled, like using boot time parameter options. The three
patches were fixing the issues by avoiding starting DAMON before the
module initialization phase.
However, probably by a mistake during a merge, only half of the change is
merged, and the part for avoiding the starting of DAMON before the module
initialized is missed. So the problem is not solved and thus the modules
can still crash if enabled before DAMON is initialized. Fix those by
applying the unmerged parts again.
Note that the broken commits are merged into 6.17-rc1, but also backported
to relevant stable kernels. So this series also needs to be merged into
the stable kernels. Hence Cc-ing stable@.
This patch (of 3):
Commit 0ed1165c37 ("samples/damon/wsse: fix boot time enable handling")
is somehow incompletely applying the origin patch [2]. 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/20250909022238.2989-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250909022238.2989-2-sj@kernel.org
Link: https://lkml.kernel.org/r/20250706193207.39810-1-sj@kernel.org [1]
Link: https://lore.kernel.org/20250706193207.39810-2-sj@kernel.org [2]
Fixes: 0ed1165c37 ("samples/damon/wsse: fix boot time enable handling")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement cleanup_target() callback for [f]vaddr, which calls put_pid()
for each target that will be destroyed. Also remove redundant put_pid()
calls in core, sysfs and sample modules, which were required to be done
redundantly due to the lack of such self cleanup in vaddr.
Link: https://lkml.kernel.org/r/20250712195016.151108-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch adds a new knob `detect_node_addresses`, which determines
whether the physical address range is set manually using the existing
knobs or automatically by the mtier module. When `detect_node_addresses`
set to 'Y', mtier automatically converts node0 and node1 to their physical
addresses. If set to 'N', it uses the existing 'node#_start_addr' and
'node#_end_addr' to define regions as before.
Link: https://lkml.kernel.org/r/20250707235919.513-1-yunjeong.mun@sk.com
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Suggested-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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>
DAMON sample module, mtier has its name 'mtier'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON sample module, prcl has its name 'prcl'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/damon: misc cleanups".
Yet another round of miscellaneous DAMON cleanups.
This patch (of 6):
DAMON sample module, wsse has its name 'wsse'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250705175000.56259-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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: 82a08bde3c ("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>
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: 2aca254620 ("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>
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: b757c6cfc6 ("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>
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: 2aca254620 ("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>
