The patch titled Subject: samples/damon/mtier: support boot time enable setup has been added to the -mm mm-new branch. Its filename is samples-damon-mtier-support-boot-time-enable-setup.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: samples/damon/mtier: support boot time enable setup Date: Sun, 6 Jul 2025 12:32:04 -0700
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 ---
samples/damon/mtier.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
--- a/samples/damon/mtier.c~samples-damon-mtier-support-boot-time-enable-setup +++ a/samples/damon/mtier.c @@ -157,6 +157,8 @@ static void damon_sample_mtier_stop(void damon_destroy_ctx(ctxs[1]); }
+static bool init_called; + static int damon_sample_mtier_enable_store( const char *val, const struct kernel_param *kp) { @@ -170,6 +172,9 @@ static int damon_sample_mtier_enable_sto if (enable == enabled) return 0;
+ if (!init_called) + return 0; + if (enable) { err = damon_sample_mtier_start(); if (err) @@ -182,6 +187,14 @@ static int damon_sample_mtier_enable_sto
static int __init damon_sample_mtier_init(void) { + int err = 0; + + init_called = true; + if (enable) { + err = damon_sample_mtier_start(); + if (err) + enable = false; + } return 0; }
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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