linux-kernel - Re: [PATCH] autofs - use dentry flags to block walks during expire

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]

Message-ID: <s5h4m60q8xh.wl-tiwai@suse.de>
Date:   Thu, 01 Sep 2016 11:13:46 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Ian Kent <raven@...maw.net>
Cc:     Al Viro <viro@...IV.linux.org.uk>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        autofs mailing list <autofs@...r.kernel.org>,
        Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] autofs - use dentry flags to block walks during expire

On Thu, 01 Sep 2016 03:21:14 +0200,
Ian Kent wrote:
> 
> Somewhere along the way the autofs expire operation has changed to
> hold a spin lock over expired dentry selection. The autofs indirect
> mount expired dentry selection is complicated and quite lengthy so
> it isn't appropriate to hold a spin lock over the operation.
> 
> Commit 47be6184 added a might_sleep() to dput() causing a BUG()
> about this usage to be issued.
> 
> But the spin lock doesn't need to be held over this check, the
> autofs dentry info. flags are enough to block walks into dentrys
> during the expire.
> 
> I've left the direct mount expire as it is (for now) becuase it
> is much simpler and quicker than the indirect mount expire and
> adding spin lock release and re-aquires would do nothing more
> than add overhead.
> 
> Signed-off-by: Ian Kent <raven@...maw.net>

Looks working fine, so far.

Reported-and-tested-by: Takashi Iwai <tiwai@...e.de>


thanks,

Takashi