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
| ||
|
Date: Thu, 21 Feb 2008 17:05:32 +1100 From: Nigel Cunningham <nigel@...el.suspend2.net> To: Greg KH <gregkh@...e.de> CC: Matthew Garrett <mjg59@...f.ucam.org>, Jesse Barnes <jesse.barnes@...el.com>, Linus Torvalds <torvalds@...ux-foundation.org>, "Rafael J. Wysocki" <rjw@...k.pl>, Jeff Chua <jeff.chua.linux@...il.com>, lkml <linux-kernel@...r.kernel.org>, Dave Airlie <airlied@...ux.ie>, linux-acpi@...r.kernel.org, suspend-devel List <suspend-devel@...ts.sourceforge.net> Subject: Re: 2.6.25-rc2 System no longer powers off after suspend-to-disk. Screen becomes green. Hi Greg. Greg KH wrote: > On Thu, Feb 21, 2008 at 12:17:06PM +1100, Nigel Cunningham wrote: >> Hi. >> >> Greg KH wrote: >>> On Thu, Feb 21, 2008 at 11:40:06AM +1100, Nigel Cunningham wrote: >>>> Hi. >>>> >>>> Matthew Garrett wrote: >>>>> On Thu, Feb 21, 2008 at 09:45:02AM +1100, Nigel Cunningham wrote: >>>>>> - people keep talking about hibernating to an ext3 fs mounted on fuse >>>>>> as a limitation of the freezer. To do that with kexec, you're still >>>>>> going to have to bmap the ext3 fs and pass the block list (in which >>>>>> case we can also do it without kexec) or umount all the ext3/fuse part >>>>>> and remount in the kexec'd kernel. Sort of defeats the purpose, doesn't >>>>>> it? >>>>> No, with a freezer-based model you can basically *never* suspend to >>>>> anything related to FUSE or a userspace USB device or anything involving >>>>> userspace iSCSI initiators or whatever. Sure, there are cases where >>>>> moving away from the current model doesn't buy you anything, but that >>>>> doesn't mean that the current model is a good thing. It's not. The >>>>> freezer is a fundamentally broken concept. >>>> Putting drivers and filesystems in userspace is the fundamentally broken >>>> concept. Not just when it comes to the freezer. The whole idea is >>>> inherently racy. >>> Racy with regards to other things becides trying to suspend a machine? >>> If so, what? >> That depends on what sort of tangled web you want to weave. > > Lots of them :) > > We have tanks running Linux using userspace USB drivers for vision > control systems (scary, I know...) They seem to be successfully running > for many years now, and I'm interested in making sure those kinds of > things keep working. > > We also have laser welding robots with userspace PCI drivers in car > manufacturing plants. And other laser cutting robots slicing wood in > patterns moving at a rate of over 3 meters a second. Again, with > userspace drivers and Linux. > > Those users would also love to know of any potential problems you know > of for this situation. > >> Low memory situations is one other situation that occurs to me >> quickly, especially (though not only) if your ability to swap were to >> depend upon a userspace driver and/or filesystem. > > Sure, swap over a userspace filesystem or driver isn't a sane idea. And > neither is swaping over NFS over a PPP connection attached to a USB to > serial device. Yes, it's possible, and all in the kernel, but not a > wise decision. > > Other than foolish configurations, if you come up with other issues > surrounding userspace drivers that could cause problems, please let me > know. A simple OOM condition isn't an issue? Surely a driver stalling because some of its memory gets swapped out just before it goes to use it would be a problem if it resulted in getting the length of a cut wrong or caused some distorted vision or a late turn :> Am I missing something? Maybe these drivers mlock memory to avoid those issues or something like that? Regards, Nigel -- 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/
Powered by blists - more mailing lists