linux-kernel - Re: vfsmount lock issues on very large ppc64 box

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: <20110718155141.GA11013@ZenIV.linux.org.uk>
Date:	Mon, 18 Jul 2011 16:51:41 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Matthew Wilcox <matthew@....cx>,
	Anton Blanchard <anton@...ba.org>, npiggin@...nel.dk,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: vfsmount lock issues on very large ppc64 box

On Mon, Jul 18, 2011 at 11:40:08AM -0400, Christoph Hellwig wrote:
> On Mon, Jul 18, 2011 at 10:17:08AM +0200, Eric Dumazet wrote:
> > > Tim posted a patch, but it wasn't applied for unknown reasons.
> > > 
> > > https://lkml.org/lkml/2011/4/13/561
> > > 
> > 
> > Could Tim respin his patch then ?
> 
> Btw, it seems like most kern_mount users want this and he's still
> missing some like devtmpfs, sysfs or ipc.  What about splitting
> kern_mount into a variant that gets a long-term reference for these
> callers, and one that doesn't for afs/cifs/nfs automounts?

	Careful - we need to balance that on shutdown side with
mnt_make_shortterm() before the final mntput()...  Making it too
easy just on the kern_mount side will lead to easy-to-miss bugs.
For one thing, it's visible only on SMP boxen; for another there's
a lot of such internal vfsmounts (pipefs, sockets, etc.) that
are never shut down, so there'll be no easily copied examples of
what should not be forgotten on __exit side of things in obvious
places...

	FWIW, I had missed the original posting back in April - had been
without net.access then and it hadn't been resent when I came back, asked
people to resend the important ones and shitcanned the huge pile of pending
mail from the previous month...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/