linux-ext4 - Re: [PATCH 5/6] dax: Call ->iomap_begin without entry lock during dax fault

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 1 Dec 2016 15:24:47 -0700
From:   Ross Zwisler <ross.zwisler@...ux.intel.com>
To:     Jan Kara <jack@...e.cz>
Cc:     linux-fsdevel@...r.kernel.org,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        linux-ext4@...r.kernel.org, linux-mm@...ck.org,
        linux-nvdimm@...ts.01.org, Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH 5/6] dax: Call ->iomap_begin without entry lock during
 dax fault

On Thu, Nov 24, 2016 at 10:46:35AM +0100, Jan Kara wrote:
> Currently ->iomap_begin() handler is called with entry lock held. If the
> filesystem held any locks between ->iomap_begin() and ->iomap_end()
> (such as ext4 which will want to hold transaction open), this would cause
> lock inversion with the iomap_apply() from standard IO path which first
> calls ->iomap_begin() and only then calls ->actor() callback which grabs
> entry locks for DAX.

I don't see the dax_iomap_actor() grabbing any entry locks for DAX?  Is this
an issue currently, or are you just trying to make the code consistent so we
don't run into issues in the future?
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html