Revert "mm/kmemleak: move the initialisation of object to __link_object"

Patch series "Fix invalid wait context of set_track_prepare()".

Geert reported an invalid wait context[1] which is resulted by moving
set_track_prepare() inside kmemleak_lock.  This is not allowed because in
RT mode, the spinlocks can be preempted but raw_spinlocks can not, so it
is not allowd to acquire spinlocks while holding raw_spinlocks.  The
second patch fix same problem in kmemleak_update_trace().


This patch (of 2):

Move the initialisation of object back to__alloc_object() because
set_track_prepare() attempt to acquire zone->lock(spinlocks) while
__link_object is holding kmemleak_lock(raw_spinlocks).  This is not right
for RT mode.

This reverts commit 245245c2 ("mm/kmemleak: move the initialisation
of object to __link_object").

Link: https://lkml.kernel.org/r/20231115082138.2649870-1-liushixin2@huawei.com
Link: https://lkml.kernel.org/r/20231115082138.2649870-2-liushixin2@huawei.com
Fixes: 245245c2 ("mm/kmemleak: move the initialisation of object to __link_object")
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Closes: https://lore.kernel.org/linux-mm/CAMuHMdWj0UzwNaxUvcocTfh481qRJpOWwXxsJCTJfu1oCqvgdA@mail.gmail.com/ [1]
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Patrick Wang <patrick.wang.shcn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kmemleak.c

@@ -642,32 +642,16 @@ static struct kmemleak_object *__alloc_object(gfp_t gfp)
 	if (!object) {
 		pr_warn("Cannot allocate a kmemleak_object structure\n");
 		kmemleak_disable();
+		return NULL;
 	}
 
-	return object;
-}
-
-static int __link_object(struct kmemleak_object *object, unsigned long ptr,
-			 size_t size, int min_count, bool is_phys)
-{
-
-	struct kmemleak_object *parent;
-	struct rb_node **link, *rb_parent;
-	unsigned long untagged_ptr;
-	unsigned long untagged_objp;
-
 	INIT_LIST_HEAD(&object->object_list);
 	INIT_LIST_HEAD(&object->gray_list);
 	INIT_HLIST_HEAD(&object->area_list);
 	raw_spin_lock_init(&object->lock);
 	atomic_set(&object->use_count, 1);
-	object->flags = OBJECT_ALLOCATED | (is_phys ? OBJECT_PHYS : 0);
-	object->pointer = ptr;
-	object->size = kfence_ksize((void *)ptr) ?: size;
 	object->excess_ref = 0;
-	object->min_count = min_count;
 	object->count = 0;			/* white color initially */
-	object->jiffies = jiffies;
 	object->checksum = 0;
 	object->del_state = 0;
 
@@ -692,6 +676,24 @@ static int __link_object(struct kmemleak_object *object, unsigned long ptr,
 	/* kernel backtrace */
 	object->trace_handle = set_track_prepare();
 
+	return object;
+}
+
+static int __link_object(struct kmemleak_object *object, unsigned long ptr,
+			 size_t size, int min_count, bool is_phys)
+{
+
+	struct kmemleak_object *parent;
+	struct rb_node **link, *rb_parent;
+	unsigned long untagged_ptr;
+	unsigned long untagged_objp;
+
+	object->flags = OBJECT_ALLOCATED | (is_phys ? OBJECT_PHYS : 0);
+	object->pointer = ptr;
+	object->size = kfence_ksize((void *)ptr) ?: size;
+	object->min_count = min_count;
+	object->jiffies = jiffies;
+
 	untagged_ptr = (unsigned long)kasan_reset_tag((void *)ptr);
 	/*
 	 * Only update min_addr and max_addr with object