linux-kernel - [PATCH] kcsan: fix section mismatch for __write_once_size/blacklisted

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Date:   Tue,  5 May 2020 16:11:32 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     "Paul E. McKenney" <paulmck@...nel.org>,
        Marco Elver <elver@...gle.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Steven Rostedt (VMware)" <rostedt@...dmis.org>,
        Kees Cook <keescook@...omium.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        Alexander Potapenko <glider@...gle.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH] kcsan: fix section mismatch for __write_once_size/blacklisted_initcalls

Moving __write_once_size out of line causes a section mismatch warning
with clang in one instance:

WARNING: modpost: vmlinux.o(.text+0x8dc): Section mismatch in reference from the function __write_once_size() to the variable .init.data:blacklisted_initcalls
The function __write_once_size() references
the variable __initdata blacklisted_initcalls.
This is often because __write_once_size lacks a __initdata
annotation or the annotation of blacklisted_initcalls is wrong.

Remove the __init_or_module annotation from the variable as a workaround.

Fixes: dfd402a4c4ba ("kcsan: Add Kernel Concurrency Sanitizer infrastructure")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
So far, my randconfig checks found two such instances, one for read_once
and one for write_once. There are probably a couple more in random
configurations, but I guess they are rare enough that we can just work
around them like this.
---
 init/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index 8f78399697e3..441c384a73cd 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1020,7 +1020,7 @@ struct blacklist_entry {
 	char *buf;
 };
 
-static __initdata_or_module LIST_HEAD(blacklisted_initcalls);
+static LIST_HEAD(blacklisted_initcalls);
 
 static int __init initcall_blacklist(char *str)
 {
-- 
2.26.0