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From:   Paulo Alcantara <pc@cjr.nz>
To:     Shyam Prasad N <nspmangalore@gmail.com>,
        CIFS <linux-cifs@vger.kernel.org>,
        Enzo Matsumiya <ematsumiya@suse.de>
Subject: Re: Deadlock in Ubuntu 5.4 kernel
In-Reply-To: <CANT5p=qEwppcgZvbdLaABb6M-pRxyDQ05oHOb523n34tYyDqcw@mail.gmail.com>
References: <CANT5p=qEwppcgZvbdLaABb6M-pRxyDQ05oHOb523n34tYyDqcw@mail.gmail.com>
Date:   Thu, 29 Dec 2022 09:16:54 -0300
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Shyam Prasad N <nspmangalore@gmail.com> writes:

> A customer reported this deadlock in a Kubernetes setup running on Ubuntu-18.04.
> This must be a 5.4 kernel, running this code:
> https://git.launchpad.net/~canonical-kernel/ubuntu/+source/linux-azure/+git/bionic
>
> Based on the stack, it appears to be a hang in DFS reconnect codepath,
> trying to access the DFS cache lock in dfs_cache_update_vol.
>
> Can you tell if this is a known issue that has been fixed since?

Looks like this has been fixed by

        06d57378bcc9 ("cifs: Fix potential deadlock when updating vol in cifs_reconnect()")

> And if Ubuntu should backport any fix to 5.4?

I would say so.  It would probably also require others dfs related
patches to be backported in addition to the above.

> I could not find the function in the mainline codebase.

Yes, it has changed alot.