mm: kfence: apply kmemleak_ignore_phys on early allocated pool

This patch solves two issues.

(1) The pool allocated by memblock needs to unregister from
kmemleak scanning. Apply kmemleak_ignore_phys to replace the
original kmemleak_free as its address now is stored in the phys tree.

(2) The pool late allocated by page-alloc doesn't need to unregister.
Move out the freeing operation from its call path.

Link: https://lkml.kernel.org/r/20220628113714.7792-2-yee.lee@mediatek.com
Fixes: 0c24e06119 ("mm: kmemleak: add rbtree and store physical address for objects allocated with PA")
Signed-off-by: Yee Lee <yee.lee@mediatek.com>
Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/kfence/core.c

@@ -603,14 +603,6 @@ static unsigned long kfence_init_pool(void)
 		addr += 2 * PAGE_SIZE;
 	}
 
-	/*
-	 * The pool is live and will never be deallocated from this point on.
-	 * Remove the pool object from the kmemleak object tree, as it would
-	 * otherwise overlap with allocations returned by kfence_alloc(), which
-	 * are registered with kmemleak through the slab post-alloc hook.
-	 */
-	kmemleak_free(__kfence_pool);
-
 	return 0;
 }
 
@@ -623,8 +615,16 @@ static bool __init kfence_init_pool_early(void)
 
 	addr = kfence_init_pool();
 
-	if (!addr)
+	if (!addr) {
+		/*
+		 * The pool is live and will never be deallocated from this point on.
+		 * Ignore the pool object from the kmemleak phys object tree, as it would
+		 * otherwise overlap with allocations returned by kfence_alloc(), which
+		 * are registered with kmemleak through the slab post-alloc hook.
+		 */
+		kmemleak_ignore_phys(__pa(__kfence_pool));
 		return true;
+	}
 
 	/*
 	 * Only release unprotected pages, and do not try to go back and change