From: Christoph Hellwig <hch@lst.de>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>, Jan Kara <jack@suse.cz>,
axboe@kernel.dk, yuyufen@huawei.com, tj@kernel.org,
tytso@mit.edu, gregkh@linuxfoundation.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] bdi: add a ->dev_name field to struct backing_dev_info
Date: Mon, 20 Apr 2020 09:48:01 +0200 [thread overview]
Message-ID: <20200420074801.GA30795@lst.de> (raw)
In-Reply-To: <20200419160651.GA18308@lst.de>
On Sun, Apr 19, 2020 at 06:06:51PM +0200, Christoph Hellwig wrote:
> > (https://lore.kernel.org/linux-block/20200416071519.807660-4-hch@lst.de/)
> > and also to the replies to that patch? This is what I found in the replies:
> > "When driver try to to re-register bdi but without release_bdi(), the old
> > dev_name will be cover directly by the newer in bdi_register_va(). So, I am
> > not sure whether it can cause memory leak for bdi->dev_name."
> >
> > Has it been considered to avoid that leak by freeing bdi->dev_name from
> > unregister_bdi(), e.g. as follows?
>
> We'd need some protection against concurrent accesses as unregister_bdi
> can race with them. But with RCU that could be handled, so let me try
> that.
I looked into it, and while it seems doable I think this goes in the
wrong direction as it pushed the RCU knowledge into the callers. I'd
rather get something like this series in ASAP, and then for 5.8 or 5.9
move the bdi pointer to the gendisk and stop re-registering it and thus
solve the problems root cause for real.
next prev parent reply other threads:[~2020-04-20 7:48 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 16:54 bdi: fix use-after-free for dev_name(bdi->dev) v2 Christoph Hellwig
2020-04-16 16:54 ` [PATCH 1/8] bdi: move bdi_dev_name out of line Christoph Hellwig
2020-04-18 15:35 ` Bart Van Assche
2020-04-16 16:54 ` [PATCH 2/8] bdi: use bdi_dev_name() to get device name Christoph Hellwig
2020-04-18 15:37 ` Bart Van Assche
2020-04-16 16:54 ` [PATCH 3/8] bdi: add a ->dev_name field to struct backing_dev_info Christoph Hellwig
2020-04-17 8:59 ` Jan Kara
2020-04-17 13:01 ` Christoph Hellwig
2020-04-20 11:41 ` Hans de Goede
2020-04-20 11:58 ` Christoph Hellwig
2020-04-21 12:42 ` Hans de Goede
2020-04-18 15:40 ` Bart Van Assche
2020-04-19 7:58 ` Christoph Hellwig
2020-04-19 15:29 ` Bart Van Assche
2020-04-19 16:06 ` Christoph Hellwig
2020-04-20 7:48 ` Christoph Hellwig [this message]
2020-04-20 9:52 ` Jan Kara
2020-04-20 9:49 ` Jan Kara
2020-04-16 16:54 ` [PATCH 4/8] driver core: remove device_create_vargs Christoph Hellwig
2020-04-16 16:54 ` [PATCH 5/8] bdi: unexport bdi_register_va Christoph Hellwig
2020-04-18 15:41 ` Bart Van Assche
2020-04-16 16:54 ` [PATCH 6/8] bdi: remove bdi_register_owner Christoph Hellwig
2020-04-18 15:43 ` Bart Van Assche
2020-04-16 16:54 ` [PATCH 7/8] bdi: simplify bdi_alloc Christoph Hellwig
2020-04-18 15:44 ` Bart Van Assche
2020-04-16 16:54 ` [PATCH 8/8] bdi: remove the name field in struct backing_dev_info Christoph Hellwig
2020-04-18 15:45 ` Bart Van Assche
-- strict thread matches above, loose matches on Subject: below --
2020-04-16 7:15 bdi: fix use-after-free for dev_name(bdi->dev) Christoph Hellwig
2020-04-16 7:15 ` [PATCH 3/8] bdi: add a ->dev_name field to struct backing_dev_info Christoph Hellwig
2020-04-16 7:52 ` Greg KH
2020-04-16 8:34 ` Yufen Yu
2020-04-16 12:02 ` Jan Kara
2020-04-16 12:19 ` Christoph Hellwig
2020-04-16 12:22 ` Christoph Hellwig
2020-04-16 12:31 ` Jan Kara
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