kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook

Move tag_clear_highpage() loops out of the kasan_has_integrated_init()
clause as a code simplification.

This patch does no functional changes.

Link: https://lkml.kernel.org/r/587e3fc36358b88049320a89cc8dc6deaecb0cda.1643047180.git.andreyknvl@google.com
Signed-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>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index db82fac..9d14ec3 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2367,30 +2367,30 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
         * KASAN unpoisoning and memory initializion code must be
         * kept together to avoid discrepancies in behavior.
         */
+
+       /*
+        * If memory tags should be zeroed (which happens only when memory
+        * should be initialized as well).
+        */
+       if (init_tags) {
+               int i;
+
+               /* Initialize both memory and tags. */
+               for (i = 0; i != 1 << order; ++i)
+                       tag_clear_highpage(page + i);
+
+               /* Note that memory is already initialized by the loop above. */
+               init = false;
+       }
        if (kasan_has_integrated_init()) {
                if (gfp_flags & __GFP_SKIP_KASAN_POISON)
                        SetPageSkipKASanPoison(page);
 
-               if (init_tags) {
-                       int i;
-
-                       for (i = 0; i != 1 << order; ++i)
-                               tag_clear_highpage(page + i);
-               } else {
+               if (!init_tags)
                        kasan_unpoison_pages(page, order, init);
-               }
        } else {
                kasan_unpoison_pages(page, order, init);
 
-               if (init_tags) {
-                       int i;
-
-                       for (i = 0; i < 1 << order; i++)
-                               tag_clear_highpage(page + i);
-
-                       init = false;
-               }
-
                if (init)
                        kernel_init_free_pages(page, 1 << order);
        }