linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Baolin Wang <baolin.wang@linaro.org>
To: stable@vger.kernel.org, peterz@infradead.org, mingo@redhat.com
Cc: longman@redhat.com, arnd@arndb.de, baolin.wang@linaro.org,
	orsonzhai@gmail.com, vincent.guittot@linaro.org,
	linux-kernel@vger.kernel.org
Subject: [BACKPORT 4.14.y v3 1/3] locking/lockdep: Add debug_locks check in __lock_downgrade()
Date: Wed, 25 Sep 2019 18:01:36 +0800	[thread overview]
Message-ID: <4ac2e84637ceaf5ec67cfc11ad58c489778693a8.1569405445.git.baolin.wang@linaro.org> (raw)
In-Reply-To: <cover.1569405445.git.baolin.wang@linaro.org>

From: Waiman Long <longman@redhat.com>

[Upstream commit 513e1073d52e55b8024b4f238a48de7587c64ccf]

Tetsuo Handa had reported he saw an incorrect "downgrading a read lock"
warning right after a previous lockdep warning. It is likely that the
previous warning turned off lock debugging causing the lockdep to have
inconsistency states leading to the lock downgrade warning.

Fix that by add a check for debug_locks at the beginning of
__lock_downgrade().

Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzbot+53383ae265fb161ef488@syzkaller.appspotmail.com
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/1547093005-26085-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
---
 kernel/locking/lockdep.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 565005a..5c370c6 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3650,6 +3650,9 @@ static int reacquire_held_locks(struct task_struct *curr, unsigned int depth,
 	unsigned int depth;
 	int i;
 
+	if (unlikely(!debug_locks))
+		return 0;
+
 	depth = curr->lockdep_depth;
 	/*
 	 * This function is about (re)setting the class of a held lock,
-- 
1.7.9.5


  reply	other threads:[~2019-09-25 10:01 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 10:00 [BACKPORT 4.14.y v3 0/3] Candidates from Spreadtrum 4.14 product kernel Baolin Wang
2019-09-25 10:01 ` Baolin Wang [this message]
2019-09-25 14:05   ` [BACKPORT 4.14.y v3 1/3] locking/lockdep: Add debug_locks check in __lock_downgrade() Waiman Long
2019-09-26  2:04     ` Baolin Wang
2019-09-25 10:02 ` [BACKPORT 4.14.y v3 2/3] pinctrl: sprd: Use define directive for sprd_pinconf_params values Baolin Wang
2019-09-25 10:03 ` [BACKPORT 4.14.y v3 3/3] power: supply: sysfs: ratelimit property read error message Baolin Wang

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4ac2e84637ceaf5ec67cfc11ad58c489778693a8.1569405445.git.baolin.wang@linaro.org \
    --to=baolin.wang@linaro.org \
    --cc=arnd@arndb.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=longman@redhat.com \
    --cc=mingo@redhat.com \
    --cc=orsonzhai@gmail.com \
    --cc=peterz@infradead.org \
    --cc=stable@vger.kernel.org \
    --cc=vincent.guittot@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).