linux-kernel - [PATCH] printk_legacy_map: use LD_WAIT_CONFIG instead of LD_WAIT

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Message-ID: <20251022154115.GA22400@redhat.com>
Date: Wed, 22 Oct 2025 17:41:15 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	John Ogness <john.ogness@...utronix.de>,
	Petr Mladek <pmladek@...e.com>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] printk_legacy_map: use LD_WAIT_CONFIG instead of
 LD_WAIT_SLEEP

printk_legacy_map is used on !PREEMPT_RT to avoid false positives from
CONFIG_PROVE_RAW_LOCK_NESTING about raw_spinlock/spinlock nesting.

However, LD_WAIT_SLEEP is not exactly right; it fools lockdep as if it
is fine to acquire a sleeping lock.

Change DEFINE_WAIT_OVERRIDE_MAP(printk_legacy_map) to use LD_WAIT_CONFIG.

(We can also make printk_legacy_allow_spinlock_enter/exit() depend on
 !PREEMPT_RT && CONFIG_PROVE_RAW_LOCK_NESTING)

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/printk/printk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 5aee9ffb16b9..f11b2f31999b 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3007,7 +3007,7 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
  * false positive. For PREEMPT_RT the false positive condition does not
  * occur.
  *
- * This map is used to temporarily establish LD_WAIT_SLEEP context for the
+ * This map is used to temporarily establish LD_WAIT_CONFIG context for the
  * console write() callback when legacy printing to avoid false positive
  * lockdep complaints, thus allowing lockdep to continue to function for
  * real issues.
@@ -3016,7 +3016,7 @@ bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
 static inline void printk_legacy_allow_spinlock_enter(void) { }
 static inline void printk_legacy_allow_spinlock_exit(void) { }
 #else
-static DEFINE_WAIT_OVERRIDE_MAP(printk_legacy_map, LD_WAIT_SLEEP);
+static DEFINE_WAIT_OVERRIDE_MAP(printk_legacy_map, LD_WAIT_CONFIG);
 
 static inline void printk_legacy_allow_spinlock_enter(void)
 {
-- 
2.25.1.362.g51ebf55