[PATCH v3 1/2] mm/kmemleak: use object_cache instead of kmemleak_initialized to check in set_track_prepare()

[Xiaolei Wang]

kmemleak_initialized is set in kmemleak_late_init(), which
also means that there is no call trace which object's memory
leak is before kmemleak_late_init(), so use object_cache instead
of kmemleak_initialized to check in set_track_prepare() to avoid
no call trace records when there is a memory leak in the code
between kmemleak_init() and kmemleak_late_init().

unreferenced object 0xc674ca80 (size 64):
 comm "swapper/0", pid 1, jiffies 4294938337 (age 204.880s)
 hex dump (first 32 bytes):
  80 55 75 c6 80 54 75 c6 00 55 75 c6 80 52 75 c6 .Uu..Tu..Uu..Ru.
  00 53 75 c6 00 00 00 00 00 00 00 00 00 00 00 00 .Su..........

Fixes: 56a61617dd22 ("mm: use stack_depot for recording kmemleak's backtrace")
Signed-off-by: Xiaolei Wang <xiaolei.wang@xxxxxxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
---
 mm/kmemleak.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index a2d34226e3c8..16fc7b0984b9 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -610,7 +610,12 @@ static noinline depot_stack_handle_t set_track_prepare(void)
 	unsigned long entries[MAX_TRACE];
 	unsigned int nr_entries;
 
-	if (!kmemleak_initialized)
+	/*
+	 * Use object_cache to determine whether kmemleak_init() has
+	 * been invoked. stack_depot_early_init() is called before
+	 * kmemleak_init() in mm_core_init().
+	 */
+	if (!object_cache)
 		return 0;
 	nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
 	trace_handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
-- 
2.25.1