linux-kernel - [PATCH v6 09/39] kasan, page_alloc: refactor init checks in post_alloc

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Date:   Mon, 24 Jan 2022 19:02:17 +0100
From:   andrey.konovalov@...ux.dev
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Peter Collingbourne <pcc@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH v6 09/39] kasan, page_alloc: refactor init checks in post_alloc_hook

From: Andrey Konovalov <andreyknvl@...gle.com>

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.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>

---

Changes v2->v3:
- Update patch description.
---
 mm/page_alloc.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8481420d2502..868480d463c7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2420,19 +2420,21 @@ 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);
-- 
2.25.1