linux-kernel - [PATCH v2 11/12] arch/um: don't initialize kasan if it's disabled

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Message-ID: <20250812124941.69508-12-bhe@redhat.com>
Date: Tue, 12 Aug 2025 20:49:40 +0800
From: Baoquan He <bhe@...hat.com>
To: linux-mm@...ck.org
Cc: ryabinin.a.a@...il.com,
	glider@...gle.com,
	andreyknvl@...il.com,
	dvyukov@...gle.com,
	vincenzo.frascino@....com,
	akpm@...ux-foundation.org,
	kasan-dev@...glegroups.com,
	linux-kernel@...r.kernel.org,
	kexec@...ts.infradead.org,
	sj@...nel.org,
	lorenzo.stoakes@...cle.com,
	elver@...gle.com,
	snovitoll@...il.com,
	Baoquan He <bhe@...hat.com>
Subject: [PATCH v2 11/12] arch/um: don't initialize kasan if it's disabled

And also add code to enable kasan_flag_enabled, this is for later
usage. Since kasan_init() is called before main(), enabling
kasan_flag_enabled is done in arch_mm_preinit() which is after
jump_label_init() invocation.

Signed-off-by: Baoquan He <bhe@...hat.com>
---
 arch/um/kernel/mem.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 76bec7de81b5..392a23d4ef96 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -26,6 +26,9 @@
 int kasan_um_is_ready;
 void kasan_init(void)
 {
+
+	if (kasan_arg_disabled)
+		return;
 	/*
 	 * kasan_map_memory will map all of the required address space and
 	 * the host machine will allocate physical memory as necessary.
@@ -58,6 +61,9 @@ static unsigned long brk_end;
 
 void __init arch_mm_preinit(void)
 {
+	/* Safe to call after jump_label_init(). Enables KASAN. */
+	static_branch_enable(&kasan_flag_enabled);
+
 	/* clear the zero-page */
 	memset(empty_zero_page, 0, PAGE_SIZE);
 
-- 
2.41.0