linux-kernel - [tip: locking/core] locking/lockdep: Avoid unmatched unlock

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Date:   Mon, 08 Feb 2021 12:06:34 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Dmitry Vyukov <dvyukov@...gle.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Waiman Long <longman@...hat.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: locking/core] locking/lockdep: Avoid unmatched unlock

The following commit has been merged into the locking/core branch of tip:

Commit-ID:     7f82e631d236cafd28518b998c6d4d8dc2ef68f6
Gitweb:        https://git.kernel.org/tip/7f82e631d236cafd28518b998c6d4d8dc2ef68f6
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Mon, 01 Feb 2021 11:55:38 +01:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 05 Feb 2021 17:20:15 +01:00

locking/lockdep: Avoid unmatched unlock

Commit f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI"
inversions") overlooked that print_usage_bug() releases the graph_lock
and called it without the graph lock held.

Fixes: f6f48e180404 ("lockdep: Teach lockdep about "USED" <- "IN-NMI" inversions")
Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Waiman Long <longman@...hat.com>
Link: https://lkml.kernel.org/r/YBfkuyIfB1+VRxXP@hirez.programming.kicks-ass.net
---
 kernel/locking/lockdep.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index ad9afd8..5104db0 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3773,7 +3773,7 @@ static void
 print_usage_bug(struct task_struct *curr, struct held_lock *this,
 		enum lock_usage_bit prev_bit, enum lock_usage_bit new_bit)
 {
-	if (!debug_locks_off_graph_unlock() || debug_locks_silent)
+	if (!debug_locks_off() || debug_locks_silent)
 		return;
 
 	pr_warn("\n");
@@ -3814,6 +3814,7 @@ valid_state(struct task_struct *curr, struct held_lock *this,
 	    enum lock_usage_bit new_bit, enum lock_usage_bit bad_bit)
 {
 	if (unlikely(hlock_class(this)->usage_mask & (1 << bad_bit))) {
+		graph_unlock();
 		print_usage_bug(curr, this, bad_bit, new_bit);
 		return 0;
 	}