From: Bart Van Assche <bvanassche@acm.org>
To: Johannes Berg <johannes@sipsolutions.net>, Tejun Heo <tj@kernel.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
"tytso@mit.edu" <tytso@mit.edu>
Subject: Re: [PATCH 3/3] kernel/workqueue: Suppress a false positive lockdep complaint
Date: Thu, 25 Oct 2018 10:11:51 -0700 [thread overview]
Message-ID: <1540487511.66186.31.camel@acm.org> (raw)
In-Reply-To: <2cebeb88640433ce473bc40f9a5c7e06d0661e4d.camel@sipsolutions.net>
On Thu, 2018-10-25 at 19:02 +0200, Johannes Berg wrote:
> On Thu, 2018-10-25 at 15:05 +0000, Bart Van Assche wrote:
> > It can happen that the direct I/O queue creates and destroys an empty
> > workqueue from inside a work function.
>
> So, thinking about this more, can you guarantee (somehow) that the
> workqueue is empty at this point?
In general, no. But for the direct I/O case this can be guaranteed. Please
have a look at the code in sb_init_dio_done_wq() if you would not yet have
done this.
> Do you know how to reproduce this?
The lockdep complaint in the patch description is easy to reproduce. The
way I reproduce it is as follows:
git clone https://github.com/osandov/blktests
(cd blktests && ./check -q nvmeof-mp)
Bart.
next prev parent reply other threads:[~2018-10-25 17:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-25 15:05 [PATCH 0/3] Suppress false positives triggered by workqueue lockdep annotations Bart Van Assche
2018-10-25 15:05 ` [PATCH 1/3] kernel/workqueue: Remove lockdep annotation from __flush_work() Bart Van Assche
2018-10-25 15:31 ` Johannes Berg
2018-10-25 15:57 ` Johannes Berg
2018-10-25 16:01 ` Bart Van Assche
2018-10-25 15:05 ` [PATCH 2/3] kernel/workqueue: Surround work execution with shared lock annotations Bart Van Assche
2018-10-25 16:53 ` Johannes Berg
2018-10-25 17:22 ` Bart Van Assche
2018-10-25 19:17 ` Johannes Berg
2018-10-25 15:05 ` [PATCH 3/3] kernel/workqueue: Suppress a false positive lockdep complaint Bart Van Assche
2018-10-25 15:34 ` Johannes Berg
2018-10-25 15:55 ` Bart Van Assche
2018-10-25 19:59 ` Johannes Berg
2018-10-25 20:21 ` Theodore Y. Ts'o
2018-10-25 20:26 ` Johannes Berg
2018-10-25 15:36 ` Tejun Heo
2018-10-25 15:37 ` Tejun Heo
2018-10-25 20:13 ` Johannes Berg
2018-10-25 15:40 ` Theodore Y. Ts'o
2018-10-25 17:02 ` Johannes Berg
2018-10-25 17:11 ` Bart Van Assche [this message]
2018-10-25 19:51 ` Johannes Berg
2018-10-25 20:39 ` Bart Van Assche
2018-10-25 20:47 ` Johannes Berg
2018-10-25 15:27 ` [PATCH 0/3] Suppress false positives triggered by workqueue lockdep annotations Johannes Berg
2018-10-25 15:47 ` Bart Van Assche
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=1540487511.66186.31.camel@acm.org \
--to=bvanassche@acm.org \
--cc=hch@lst.de \
--cc=johannes@sipsolutions.net \
--cc=linux-kernel@vger.kernel.org \
--cc=sagi@grimberg.me \
--cc=tj@kernel.org \
--cc=tytso@mit.edu \
/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.