From: "J. R. Okajima" <hooanon05g@gmail.com>
To: peterz@infradead.org
Cc: linux-kernel@vger.kernel.org, axboe@fb.com,
darrick.wong@oracle.com, david@fromorbit.com
Subject: Q: lockdep_assert_held_read() after downgrade_write()
Date: Tue, 31 Jan 2017 06:25:42 +0900 [thread overview]
Message-ID: <18295.1485811542@jrobl> (raw)
Peter Zijlstra,
May I ask you a question?
v4.10-rc1 got a commit
f831948 2016-11-30 locking/lockdep: Provide a type check for lock_is_held
I've tested a little and lockdep splat a stack trace.
{
DECLARE_RWSEM(rw);
static struct lock_class_key key;
lockdep_set_class(&rw, &key);
down_read(&rw);
lockdep_assert_held_read(&rw);
up_read(&rw);
down_write(&rw);
lockdep_assert_held_exclusive(&rw);
up_write(&rw);
downgrade_write(&rw);
lockdep_assert_held_read(&rw); <-- here
up_read(&rw);
}
I was expecting that lockdep_assert_held_read() splat nothing after
downgrade_write(). Is this warning an intentional behaviour?
Also the final up_read() gives me a warning too. It is produced at
lockdep.c:3514:lock_release(): DEBUG_LOCKS_WARN_ON(depth <= 0)
As an additional information, I increased some lockdep constants.
Do you think this is related?
include/linux/lockdep.h
+#define MAX_LOCKDEP_SUBCLASSES (8UL + 4)
+#define MAX_LOCKDEP_KEYS_BITS (13 + 3)
kernel/locking/lockdep_internals.h
+#define MAX_LOCKDEP_ENTRIES (32768UL << 5)
+#define MAX_LOCKDEP_CHAINS_BITS (16 + 5)
+#define MAX_STACK_TRACE_ENTRIES (524288UL << 5)
J. R. Okajima
next reply other threads:[~2017-01-30 21:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-30 21:25 J. R. Okajima [this message]
2017-01-30 21:30 ` Q: lockdep_assert_held_read() after downgrade_write() Jens Axboe
2017-01-31 10:36 ` Peter Zijlstra
2017-01-31 11:25 ` Peter Zijlstra
2017-01-31 14:23 ` Waiman Long
2017-01-31 14:26 ` Peter Zijlstra
2017-01-31 15:40 ` J. R. Okajima
2017-01-31 16:32 ` Peter Zijlstra
2017-02-02 16:33 ` J. R. Okajima
2017-02-02 16:38 ` [PATCH 1/3] lockdep: consolidate by new find_held_lock() J. R. Okajima
2017-02-02 16:38 ` [PATCH 2/3] lockdep: consolidate by new validate_held_lock() J. R. Okajima
2017-02-14 12:09 ` Peter Zijlstra
2017-03-16 11:25 ` [tip:locking/core] locking/lockdep: Factor out the validate_held_lock() helper function tip-bot for J. R. Okajima
2017-02-02 16:38 ` [PATCH 3/3] lockdep: new annotation lock_downgrade() J. R. Okajima
2017-02-02 17:59 ` kbuild test robot
2017-02-02 18:45 ` Peter Zijlstra
2017-02-02 21:05 ` J. R. Okajima
2017-02-14 12:11 ` Peter Zijlstra
2017-03-16 11:25 ` [tip:locking/core] locking/lockdep: Add new check to lock_downgrade() tip-bot for J. R. Okajima
2017-03-16 11:24 ` [tip:locking/core] locking/lockdep: Factor out the find_held_lock() helper function tip-bot for J. R. Okajima
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=18295.1485811542@jrobl \
--to=hooanon05g@gmail.com \
--cc=axboe@fb.com \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.