debugobject: Ensure pool refill (again)

The recent fix to ensure atomicity of lookup and allocation inadvertently
broke the pool refill mechanism.

Prior to that change debug_objects_activate() and debug_objecs_assert_init()
invoked debug_objecs_init() to set up the tracking object for statically
initialized objects. That's not longer the case and debug_objecs_init() is
now the only place which does pool refills.

Depending on the number of statically initialized objects this can be
enough to actually deplete the pool, which was observed by Ido via a
debugobjects OOM warning.

Restore the old behaviour by adding explicit refill opportunities to
debug_objects_activate() and debug_objecs_assert_init().

Fixes: 63a759694eed ("debugobject: Prevent init race with static objects")
Reported-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Link: https://lore.kernel.org/r/871qk05a9d.ffs@tglx

diff --git a/lib/debugobjects.c b/lib/debugobjects.c
index b796799fadb20f89a74db204fcf31b496ad0184d..003edc5ebd6730feede2d4999372b6d339ec7d65 100644 (file)
--- a/lib/debugobjects.c
+++ b/lib/debugobjects.c
@@ -587,6 +587,16 @@ static struct debug_obj *lookup_object_or_alloc(void *addr, struct debug_bucket
        return NULL;
 }
 
+static void debug_objects_fill_pool(void)
+{
+       /*
+        * On RT enabled kernels the pool refill must happen in preemptible
+        * context:
+        */
+       if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible())
+               fill_pool();
+}
+
 static void
 __debug_object_init(void *addr, const struct debug_obj_descr *descr, int onstack)
 {
@@ -595,12 +605,7 @@ __debug_object_init(void *addr, const struct debug_obj_descr *descr, int onstack
        struct debug_obj *obj;
        unsigned long flags;
 
-       /*
-        * On RT enabled kernels the pool refill must happen in preemptible
-        * context:
-        */
-       if (!IS_ENABLED(CONFIG_PREEMPT_RT) || preemptible())
-               fill_pool();
+       debug_objects_fill_pool();
 
        db = get_bucket((unsigned long) addr);
 
@@ -685,6 +690,8 @@ int debug_object_activate(void *addr, const struct debug_obj_descr *descr)
        if (!debug_objects_enabled)
                return 0;
 
+       debug_objects_fill_pool();
+
        db = get_bucket((unsigned long) addr);
 
        raw_spin_lock_irqsave(&db->lock, flags);
@@ -894,6 +901,8 @@ void debug_object_assert_init(void *addr, const struct debug_obj_descr *descr)
        if (!debug_objects_enabled)
                return;
 
+       debug_objects_fill_pool();
+
        db = get_bucket((unsigned long) addr);
 
        raw_spin_lock_irqsave(&db->lock, flags);