The patch titled Subject: samples/damon/wsse: fix boot time enable handling has been added to the -mm mm-new branch. Its filename is samples-damon-wsse-fix-boot-time-enable-handling.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: samples/damon/wsse: fix boot time enable handling Date: Sun, 6 Jul 2025 12:32:02 -0700
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 ---
samples/damon/wsse.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
--- a/samples/damon/wsse.c~samples-damon-wsse-fix-boot-time-enable-handling +++ a/samples/damon/wsse.c @@ -89,6 +89,8 @@ static void damon_sample_wsse_stop(void) put_pid(target_pidp); }
+static bool init_called; + static int damon_sample_wsse_enable_store( const char *val, const struct kernel_param *kp) { @@ -103,6 +105,9 @@ static int damon_sample_wsse_enable_stor return 0;
if (enable) { + if (!init_called) + return 0; + err = damon_sample_wsse_start(); if (err) enable = false; @@ -114,7 +119,15 @@ static int damon_sample_wsse_enable_stor
static int __init damon_sample_wsse_init(void) { - return 0; + int err = 0; + + init_called = true; + if (enable) { + err = damon_sample_wsse_start(); + if (err) + enable = false; + } + return err; }
module_init(damon_sample_wsse_init); _
Patches currently in -mm which might be from sj@kernel.org are
mm-damon-core-handle-damon_call_control-as-normal-under-kdmond-deactivation.patch mm-damon-introduce-damon_stat-module.patch mm-damon-introduce-damon_stat-module-fix.patch mm-damon-stat-calculate-and-expose-estimated-memory-bandwidth.patch mm-damon-stat-calculate-and-expose-idle-time-percentiles.patch docs-admin-guide-mm-damon-add-damon_stat-usage-document.patch mm-damon-paddr-use-alloc_migartion_target-with-no-migration-fallback-nodemask.patch revert-mm-rename-alloc_demote_folio-to-alloc_migrate_folio.patch revert-mm-make-alloc_demote_folio-externally-invokable-for-migration.patch selftets-damon-add-a-test-for-memcg_path-leak.patch mm-damon-sysfs-schemes-decouple-from-damos_quota_goal_metric.patch mm-damon-sysfs-schemes-decouple-from-damos_action.patch mm-damon-sysfs-schemes-decouple-from-damos_wmark_metric.patch mm-damon-sysfs-schemes-decouple-from-damos_filter_type.patch mm-damon-sysfs-decouple-from-damon_ops_id.patch selftests-damon-add-drgn-script-for-extracting-damon-status.patch selftests-damon-_damon_sysfs-set-kdamondpid-in-start.patch selftests-damon-add-python-and-drgn-based-damon-sysfs-test.patch selftests-damon-sysfspy-test-monitoring-attribute-parameters.patch selftests-damon-sysfspy-test-adaptive-targets-parameter.patch selftests-damon-sysfspy-test-damos-schemes-parameters-setup.patch mm-damon-add-trace-event-for-auto-tuned-monitoring-intervals.patch mm-damon-add-trace-event-for-effective-size-quota.patch samples-damon-wsse-fix-boot-time-enable-handling.patch samples-damon-prcl-fix-boot-time-enable-crash.patch samples-damon-mtier-support-boot-time-enable-setup.patch mm-damon-reclaim-reset-enabled-when-damon-start-failed.patch mm-damon-lru_sort-reset-enabled-when-damon-start-failed.patch mm-damon-reclaim-use-parameter-context-correctly.patch