linux-kernel - [PATCH 04/31] kasan, page_alloc: simplify kasan_poison

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Message-Id: <b28f30ed5d662439fd2354b7a05e4d58a2889e5f.1638308023.git.andreyknvl@google.com>
Date:   Tue, 30 Nov 2021 22:39:10 +0100
From:   andrey.konovalov@...ux.dev
To:     Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Peter Collingbourne <pcc@...gle.com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        kasan-dev@...glegroups.com,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Evgenii Stepanov <eugenis@...gle.com>,
        linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 04/31] kasan, page_alloc: simplify kasan_poison_pages call site

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

Simplify the code around calling kasan_poison_pages() in
free_pages_prepare().

Reording kasan_poison_pages() and kernel_init_free_pages() is OK,
since kernel_init_free_pages() can handle poisoned memory.

This patch does no functional changes besides reordering the calls.

Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 mm/page_alloc.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3f3ea41f8c64..0673db27dd12 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1289,6 +1289,7 @@ static __always_inline bool free_pages_prepare(struct page *page,
 {
 	int bad = 0;
 	bool skip_kasan_poison = should_skip_kasan_poison(page, fpi_flags);
+	bool init = want_init_on_free();
 
 	VM_BUG_ON_PAGE(PageTail(page), page);
 
@@ -1359,19 +1360,10 @@ static __always_inline bool free_pages_prepare(struct page *page,
 	 * With hardware tag-based KASAN, memory tags must be set before the
 	 * page becomes unavailable via debug_pagealloc or arch_free_page.
 	 */
-	if (kasan_has_integrated_init()) {
-		bool init = want_init_on_free();
-
-		if (!skip_kasan_poison)
-			kasan_poison_pages(page, order, init);
-	} else {
-		bool init = want_init_on_free();
-
-		if (init)
-			kernel_init_free_pages(page, 1 << order);
-		if (!skip_kasan_poison)
-			kasan_poison_pages(page, order, init);
-	}
+	if (!skip_kasan_poison)
+		kasan_poison_pages(page, order, init);
+	if (init && !kasan_has_integrated_init())
+		kernel_init_free_pages(page, 1 << order);
 
 	/*
 	 * arch_free_page() can make the page's contents inaccessible.  s390
-- 
2.25.1