kasan, page_alloc: move kernel_init_free_pages in post_alloc_hook

Pull the kernel_init_free_pages() call in post_alloc_hook() out of the big
if clause for better code readability.  This also allows for more
simplifications in the following patch.

This patch does no functional changes.

Link: https://lkml.kernel.org/r/a7a76456501eb37ddf9fca6529cee9555e59cdb1.1643047180.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Acked-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -2383,14 +2383,18 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
 		init = false;
 	}
 	if (kasan_has_integrated_init()) {
-		if (!init_tags)
+		if (!init_tags) {
 			kasan_unpoison_pages(page, order, init);
+
+			/* Note that memory is already initialized by KASAN. */
+			init = false;
+		}
 	} else {
 		kasan_unpoison_pages(page, order, init);
-
+	}
+	/* If memory is still not initialized, do it now. */
 	if (init)
 		kernel_init_free_pages(page, 1 << order);
-	}
 	/* Propagate __GFP_SKIP_KASAN_POISON to page flags. */
 	if (kasan_hw_tags_enabled() && (gfp_flags & __GFP_SKIP_KASAN_POISON))
 		SetPageSkipKASanPoison(page);