Re: kernel panic when unmount removed usbdrive
On Fri, 29 Feb 2008 00:06:57 +0100 Henrik Gulbrandsen <[EMAIL PROTECTED]> wrote: > You know, the good thing about thinking something is easy is that you > get the nerve to actually start working on the problem. I agree that > it is not a trivial fix. I pride myself on being able to fix almost > any bug within a day. At least, that's what it says on my business > cards, but in this case there were several underlying issues, so say > one week of deep analysis and patching to reach the state where I > couldn't reproduce any version of the problem. I'd call that "hard", > not "very hard" :-) My use of the phrase "very hard" here didn't reflect only on the technical issues of the problem, but all the issues: 1. there are a limited (very limited?) number of developers with enough insight to even try to fix this prtoblem 2. the problem has been around for so long that any "new" or "fresh" developers will also hear that this problem is hard to fix, and thus probably avoid it 3. seasoned FreeBSD users and developers know how to workaround; and thus the problem remains "out of sight" 4. the few people who could fix this problem doesn't have enough free time to meet and discuss how to best solve it It is very good that you have done something with the problem in spite of all this. Keep up the good work! > There is a piece of potential wisdom that I've been toying with > lately: You get the life you accept. Read that again and give it some > thought! What you accept. Not the life you want, not even the life > you deserve, but the life you accept, because that is where you will > stop striving for something even better. In this case, I have no > doubt that the very moment we decide that it is truly unacceptable > for a FreeBSD kernel to panic in a common scenario like this, that is > when we will start to see some really quick progress in this area. I agree - you get the life you accept. In my case, FreeBSD is just a very small part of my life (hey - it's just an operating system for computers, and life is so much more than computers to me), which means that the time I am willing to spend on problems in FreeBSD has to be weighed against other activites. That said - FreeBSD _is_ my favorite operating system. -- Regards, Torfinn Ingolfsen ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: kernel panic when unmount removed usbdrive
On Thu, 28 Feb 2008 11:02:03 -0600 Octavian Covalschi <[EMAIL PROTECTED]> wrote: > no, i don't think it is easy, if it was i think it already been fixed I did not imply that you were in the group "most people". :) > it is not a hobby to remove storage before unmounting it, it's just > happened, i even did not think it could > bring kernel panic. > in this case is a usbdrive.. but what happens if i have a usb hdd > drive? it will be the same? having a laptop and a portable > hdd may bring in situation that i just remove it form usb... Yes, it will be the same. anay removable media (at least the ones that end up being mounted) will behave this way, AFAIK. I'm sure someone will correct me if I'm wrong. > actually as far i know usb is intented to have hotswap devices. > anyway, i'm just a user, and hearing and advice: "don't do that" it > is VERY unprofessional I agree. However, this is the status quo right now, and has been for at least 4 years. There is no orher workaround - we (FreeBSD users) will have to live with this until developers who can fix this can free up enough time to do so. Note: am not blaming any developers for the sad state we're in - after all, this is a volunteer project. > i can understand that it can be difficult, i'm a programmer too, but > anyway just to sat don';t do that is not at least nice :) > > > > If you can't learn to live with this workaround, please do not use > > removable mass storage devices with FreeBSD. > > > > don't be so mean :) No mean-nesss was intended, just trying to tell you in very clear terms what the state of this problem is. Yes, it is harsh, but we will have to live with it for now. -- Regards, Torfinn Ingolfsen ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: kernel panic when unmount removed usbdrive
In message: <[EMAIL PROTECTED]> Henrik Gulbrandsen <[EMAIL PROTECTED]> writes: : Right now, your best bet is to take Warner's advice and try 8.0-CURRENT, : since none of the known patches have been merged to the 7.0 track yet. : However, I honestly don't know how he can get anything stable without : the final scsi_da.c patch, since I had something like 100% reproducible : crashes when I updated my system from late 7.0 to early 8.0. You might : want to apply patches from http://www.gulbra.net/freebsd-usb/ yourself, : but keep in mind that CURRENT is a moving target, so I can't guarantee : that the patches are still working perfectly. Also, please remember to : use -o sync when mounting the drive. The other case is less tested... Henrik, I've not forgotten your patches, but I haven't had the time to integrate them into the system. I hope to have them ready by 8.0, and if I'm lucky, in time to MFC for 7.1. Many of them are MFCable, although some of the underlying issues they expose can only be fixed properly in head since they may require ABI changes. The changes should really be done at the fs level, since the current patches will leak resources and potentially have other bad effects. I'd also like to have something between full sync and async when mounting removable file systems. You want synchronous metadata, but async data blocks for performance often times. I'm still exploring what this means... Finally, I'd like to thank you again publicly for taking the time and initiative to see through the difficulties of this problem and to persist in presenting your solution to the developers. It made me lose my fear of the buffer cache code, which ultimately will be a good thing. Warner ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: kernel panic when unmount removed usbdrive
I think I've already made my point regarding this bug, but since I stay on this mailing list primarily to see the fix through to completion, it would be silly not to comment when everyone else seems to do that :-) On Thu, 2008-02-28 at 09:27 -0600, Octavian Covalschi wrote: > this problem is known at least for 1 year.. this is bad. The problem was known over five years ago (usb/46176). I offered a first working patch set for private review in September 2004, but never took the time to follow up. With hindsight, that was a mistake. You see, the thing is that the panic-at-usb-drive-removal bug has been with us for so long that most long-term FreeBSD users have gotten used to it. They know that the drive must be unmounted before the USB stick can be pulled out, and they have probably forgotten the horror experienced when they first made the pull-out-first mistake themselves. That is why you get advice like "don't do that", although a bug fix is a very reasonable request. > anybody knows any work-around ? Right now, your best bet is to take Warner's advice and try 8.0-CURRENT, since none of the known patches have been merged to the 7.0 track yet. However, I honestly don't know how he can get anything stable without the final scsi_da.c patch, since I had something like 100% reproducible crashes when I updated my system from late 7.0 to early 8.0. You might want to apply patches from http://www.gulbra.net/freebsd-usb/ yourself, but keep in mind that CURRENT is a moving target, so I can't guarantee that the patches are still working perfectly. Also, please remember to use -o sync when mounting the drive. The other case is less tested... > thank u in advance You're welcome! And if you're uncomfortable with applying weird patches and recompiling bleeding-edge kernels, please don't give up hope! It's hopefully just a matter of months before we have an acceptable solution in one of the official releases. On Thu, 2008-02-28 at 17:08 +0100, Torfinn Ingolfsen wrote: > This problem has been known for a lot longer time. > However, "most people" only complain about it - and they also think it > is easy to fix this problem. > > Well, it is not easy - in fact it is very hard to fix this problem. For > data on this, please search the mailing list archives of FreeBSD. You know, the good thing about thinking something is easy is that you get the nerve to actually start working on the problem. I agree that it is not a trivial fix. I pride myself on being able to fix almost any bug within a day. At least, that's what it says on my business cards, but in this case there were several underlying issues, so say one week of deep analysis and patching to reach the state where I couldn't reproduce any version of the problem. I'd call that "hard", not "very hard" :-) > Yes - the work around is this: don't do that! > Do _not_ remove any mass storage device before unmounting it. > > If you can't learn to live with this workaround, please do not use > removable mass storage devices with FreeBSD. There is a piece of potential wisdom that I've been toying with lately: You get the life you accept. Read that again and give it some thought! What you accept. Not the life you want, not even the life you deserve, but the life you accept, because that is where you will stop striving for something even better. In this case, I have no doubt that the very moment we decide that it is truly unacceptable for a FreeBSD kernel to panic in a common scenario like this, that is when we will start to see some really quick progress in this area. /Henrik ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: kernel panic when unmount removed usbdrive
In message: <[EMAIL PROTECTED]> Torfinn Ingolfsen <[EMAIL PROTECTED]> writes: : > anybody knows any work-around ? : : Yes - the work around is this: don't do that! : Do _not_ remove any mass storage device before unmounting it. run current and you have better results. The problem is that error propagation inside of the buffer cache code and file system code doesn't handle ENXIO very well. It takes time to work through it. One could, in theory, use QEMU to make it easier to test. Alas, I've not had time to work through the setup. Warner ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
Re: kernel panic when unmount removed usbdrive
On Thu, 28 Feb 2008 09:27:51 -0600 Octavian Covalschi <[EMAIL PROTECTED]> wrote: > hi, i've got 2 kernel panics.. when tried to unmount already removed > an usbdrive > actually i have reported this problem, but after some google found > that this is not new :( > > this problem is known at least for 1 year.. this is bad. This problem has been known for a lot longer time. However, "most people" only complain about it - and they also think it is easy to fix this problem. Well, it is not easy - in fact it is very hard to fix this problem. For data on this, please search the mailing list archives of FreeBSD. > anybody knows any work-around ? Yes - the work around is this: don't do that! Do _not_ remove any mass storage device before unmounting it. If you can't learn to live with this workaround, please do not use removable mass storage devices with FreeBSD. HTH -- Regards, Torfinn Ingolfsen ___ freebsd-usb@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-usb To unsubscribe, send any mail to "[EMAIL PROTECTED]"
