diff options
| -rw-r--r-- | Documentation/dev-tools/kmemleak.rst | 8 | ||||
| -rw-r--r-- | mm/kmemleak.c | 13 |
2 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/dev-tools/kmemleak.rst b/Documentation/dev-tools/kmemleak.rst index 7d784e03f3f9..a8a83bc69ceb 100644 --- a/Documentation/dev-tools/kmemleak.rst +++ b/Documentation/dev-tools/kmemleak.rst @@ -198,6 +198,14 @@ systems, because of pointers temporarily stored in CPU registers or stacks. Kmemleak defines MSECS_MIN_AGE (defaulting to 1000) representing the minimum age of an object to be reported as a memory leak. +The ``min_unref_scans`` module parameter (default 1) requires an object to +be seen unreferenced in that many consecutive scans before it is reported. +Keeping it at 1 preserves the historical behaviour; higher values filter +the transient false positives described above, at the cost of delaying +genuine reports by up to that many scans. It can be set at boot with +``kmemleak.min_unref_scans=<n>`` or at run-time via +``/sys/module/kmemleak/parameters/min_unref_scans``. + Limitations and Drawbacks ------------------------- diff --git a/mm/kmemleak.c b/mm/kmemleak.c index 95bd8ccd3c5b..7afd08ed8546 100644 --- a/mm/kmemleak.c +++ b/mm/kmemleak.c @@ -151,6 +151,8 @@ struct kmemleak_object { int min_count; /* the total number of pointers found pointing to this object */ int count; + /* consecutive scans the object has been seen unreferenced */ + unsigned int unref_scans; /* checksum for detecting modified objects */ u32 checksum; depot_stack_handle_t trace_handle; @@ -234,6 +236,9 @@ static unsigned long max_percpu_addr; static struct task_struct *scan_thread; /* used to avoid reporting of recently allocated objects */ static unsigned long jiffies_min_age; +/* consecutive scans an object must stay unreferenced before reporting */ +static unsigned int min_unref_scans = 1; +module_param(min_unref_scans, uint, 0644); static unsigned long jiffies_last_scan; /* delay between automatic memory scannings */ static unsigned long jiffies_scan_wait; @@ -692,6 +697,7 @@ static struct kmemleak_object *__alloc_object(gfp_t gfp) object->excess_ref = 0; object->count = 0; /* white color initially */ object->checksum = ~0; + object->unref_scans = 0; object->del_state = 0; /* task information */ @@ -1890,6 +1896,9 @@ static int __kmemleak_scan(bool full) __paint_it(object, KMEMLEAK_BLACK); } + /* referenced last scan: restart the unreferenced run */ + if (!color_white(object)) + object->unref_scans = 0; /* reset the reference count (whiten the object) */ object->count = 0; if (full) @@ -2064,9 +2073,11 @@ static void kmemleak_scan(void) raw_spin_lock_irq(&object->lock); trace_handle = 0; dedup_print = false; + if (unreferenced_object(object) && (object->flags & OBJECT_SUSPECT) && - !(object->flags & OBJECT_REPORTED)) { + !(object->flags & OBJECT_REPORTED) && + ++object->unref_scans >= min_unref_scans) { object->flags |= OBJECT_REPORTED; if (kmemleak_verbose) { trace_handle = object->trace_handle; |