Re: USB Attached SCSI breakage due no udev involvement

[Dio Putra]

On 5/10/20 4:48 PM, Dio Putra wrote:
> On 5/10/20 3:48 PM, Greg KH wrote:
> > On Sun, May 10, 2020 at 03:35:34PM +0700, Dio Putra wrote:
> > > On 5/10/20 2:32 PM, Greg KH wrote:
> > > > On Sun, May 10, 2020 at 02:10:04PM +0700, Dio Putra wrote:
> > > > > On 5/10/20 1:54 PM, Greg KH wrote:
> > > > > > On Sun, May 10, 2020 at 01:48:24PM +0700, Dio Putra wrote:
> > > > > > > On 5/10/20 12:47 PM, Greg KH wrote:
> > > > > > > > On Sun, May 10, 2020 at 09:55:57AM +0700, Dio Putra wrote:
> > > > > > > > > Hi, it's first time for me to report user-space breakage in here, so
> > > > > > > > > i'm begging your pardon.
> > > > > > > > >
> > > > > > > > > I want to report that Linux 5.4 breaking my USB mount workflow due
> > > > > > > > > udevadm monitor report here (I'm using vanilla kernel 5.4.39 on
> > > > > > > > > Slackware64 Current and vanilla kernel 4.4.221 on Slackware64 14.2):
> > > > > > > >
> > > > > > > > <snip>
> > > > > > > >
> > > > > > > > Sorry, but what actually changed that you can see in the logs?
> > > > > > > Sorry, what do you mean? The dmesg log or the kernel changelogs?
> > > > > >
> > > > > > Either, your message made them pretty impossible to compare with all of
> > > > > > the line-wrapping :(
> > > > > I'm so sorry for first message mess, because that message has been sent by
> > > > > Gmail Website. Can I send my logs as attachment? I try to convenient everyone
> > > > > here. ( FYI, I just switched to Thunderbird with these settings:
> > > > > https://www.kernel.org/doc/html/v4.12/process/email-clients.html#thunderbird-gui )
> > > >
> > > > Sure, attachments work, but better yet, if you can show the difference
> > > > in a few lines that is much nicer than having to dig through large
> > > > numbers of log files.
> > > Okay, I'll attach long messages and trim it as far as I can.
> >
> > Again, I really do not understand what exactly is "not working".
> >
> > Please explain that when you send the new log messages.
> Okay, here's compilation of "dmesg | grep -i udev && udevadm
> monitor && lsblk" on linux-4.4.221 vs linux-5.4.39. You can check
> my attachment here because I can't explain it by words (I'm not
> english native speaker anyway, which makes it so difficult to
> explain it for me).
>
> > > > > > > > What functionality broke?  What used to work that no longer does work?
> > > > > > > Yes, it supposed that just work and kernel could talk with udev, not just handled by the kernel.
> > > > > >
> > > > > > I don't understand, what functionality changed?  What exactly used to
> > > > > > work that no longer does?
> > > > > linux-5.4 has been never called the udev dependencies whereas
> > > > > linux-4.4 will call any udev dependencies if necessary, that's the problem.
> > > >
> > > > I do not understand what exactly you mean by "call udev dependencies".
> > > >
> > > > udev is used to create symlinks and set user/group permissions on device
> > > > nodes in /dev/ which is created by devtmpfs.  What exactly is not
> > > > happening in your /dev/ with the move to a newer kernel?
> > > Would I send my dmesg log with "udev.log-priority=debug" as attachment then?
> > >
> > > > > > Did you change anything else other than the kernel on your system?  Did
> > > > > > you change to a newer version of udev/systemd or anything else?
> > > > > I'm using eudev-master from their official mirror github:
> > > > > https://github.com/gentoo/eudev
> > > >
> > > > Have you contacted the eudev developers to see if something different
> > > > needs to be set in your kernel when moving 4 years in kernel development
> > > > forward?  Are you sure you have all the correct config options enabled?
> > > It's my bad not to contact the eudev developers first. However I'm not quite
> > > sure to contact the eudev developers would solve the problem, but CMIIW.
> > >
> > > > Why such a huge leap forward all at once, how about going from 4.4.y to
> > > > 4.9.y and then 4.14.y and then 5.4.y?  That might help narrow things
> > > > down a bit easier.
> > > Unfortunately I need to think twice due almost ran out of electricity
> > > here every time I power on my laptop for long time. So maybe I can't.
> > >
> > > But if these steps are necessary, I'll think solution later.
> >
> > Why would it take a long time to do this type of change?
> It's a weak machine, it took appropriately 2 hours to just compiling
> linux kernel. I need to think twice too because electricity is expensive here.
After deep digging into /dev/ folder, indeed some important file has 
been deleted after restart on Slackware.

On behalf from myself for linux-kernel community, I'm really sorry for 
causing these noise. Thank you Greg and all for the hints.
> > thanks,
> >
> > greg k-h