kasan, page_alloc: refactor init checks in post_alloc_hook

Separate code for zeroing memory from the code clearing tags in
post_alloc_hook().

This patch is not useful by itself but makes the simplifications in the
following patches easier to follow.

This patch does no functional changes.

Link: https://lkml.kernel.org/r/2283fde963adfd8a2b29a92066f106cc16661a3c.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 94a220d661b14cf4949f6c94bc29102df2bb9e86..d2d6e48d2d8365437fc17c8b3dfd24297ec55dbc 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2368,19 +2368,21 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
                kasan_alloc_pages(page, order, gfp_flags);
        } else {
                bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags);
+               bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS);
 
                kasan_unpoison_pages(page, order, init);
 
-               if (init) {
-                       if (gfp_flags & __GFP_ZEROTAGS) {
-                               int i;
+               if (init_tags) {
+                       int i;
 
-                               for (i = 0; i < 1 << order; i++)
-                                       tag_clear_highpage(page + i);
-                       } else {
-                               kernel_init_free_pages(page, 1 << order);
-                       }
+                       for (i = 0; i < 1 << order; i++)
+                               tag_clear_highpage(page + i);
+
+                       init = false;
                }
+
+               if (init)
+                       kernel_init_free_pages(page, 1 << order);
        }
 
        set_page_owner(page, order, gfp_flags);