From: Alexander Potapenko <glider@google.com>
Date: Mon, 28 Nov 2022 09:45:40 +0000 (+0100)
Subject: lockdep: allow instrumenting lockdep.c with KMSAN
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1e8e4a7cc2fa3017b1daf02612e095d51924ce1e;p=linux.git

lockdep: allow instrumenting lockdep.c with KMSAN

Lockdep and KMSAN used to play badly together, causing deadlocks when
KMSAN instrumentation of lockdep.c called lockdep functions recursively.

Looks like this is no more the case, and a kernel can run (yet slower)
with both KMSAN and lockdep enabled.  This patch should fix false
positives on wq_head->lock->dep_map, which KMSAN used to consider
uninitialized because of lockdep.c not being instrumented.

Link: https://lore.kernel.org/lkml/Y3b9AAEKp2Vr3e6O@sol.localdomain/
Link: https://lkml.kernel.org/r/20221128094541.2645890-1-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Reported-by: Eric Biggers <ebiggers@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Marco Elver <elver@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index ea925731fa40f..0db4093d17b8a 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -7,7 +7,6 @@ obj-y += mutex.o semaphore.o rwsem.o percpu-rwsem.o
 
 # Avoid recursion lockdep -> sanitizer -> ... -> lockdep.
 KCSAN_SANITIZE_lockdep.o := n
-KMSAN_SANITIZE_lockdep.o := n
 
 ifdef CONFIG_FUNCTION_TRACER
 CFLAGS_REMOVE_lockdep.o = $(CC_FLAGS_FTRACE)