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Cc: Jens Axboe <axboe@kernel.dk>, Pavel Emelianov <xemul@openvz.org>,
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 Chun-Yi Lee <jlee@suse.com>
To: Chun-Yi Lee <joeyli.kernel@gmail.com>, Justin Sanders <justin@coraid.com>
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From: Valentin Kleibel <valentin@vrvis.at>
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Subject: Re: [PATCH v2] aoe: fix the potential use-after-free problem in more
 places
X-SA-Exim-Version: 4.2.1 (built Wed, 06 Jul 2022 17:57:39 +0000)

> Then Nicolai Stange found more places in aoe have potential use-after-free
> problem with tx(). e.g. revalidate(), aoecmd_ata_rw(), resend(), probe()
> and aoecmd_cfg_rsp(). Those functions also use aoenet_xmit() to push
> packet to tx queue. So they should also use dev_hold() to increase the
> refcnt of skb->dev.

We've tested your patch on our servers and ran into an issue.
With heavy I/O load the aoe device had stale I/Os (e.g. rsync waiting 
indefinetly on one core) that can be "fixed" by running aoe-revalidate 
on that device.

Additionally when trying to shut down the system we see the message:
unregister_netdevice: waiting for XXX to become free. Usage Count = XXXXX
on aoe devices with a usage count somewhere in the millions.
This has been the same as without the patch, i assume the fix is still 
incomplete.

Thanks for your work,
Valentin