[uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[BlaisorBlade]

On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> On Thu, Sep 09, 2004 at 08:24:17PM +0200, BlaisorBlade wrote:
> > On Thursday 09 September 2004 15:48, Dennis Ploeger wrote:
> > > Hi!
> > >
> > > Just for your info: Done it.
> > >
> > > I've tried to deactivate swapping (and found out, where I can do that),
> > > but that wasn't the point after all. It was hwclock (which was
> > > activated _after_ activating the swap, but didn't show any output).
> > > After deactivating that, it worked.
> >
> > Thanks a lot, that makes a lot of sense. However, since you say you use
> > Debian 3.1, probably Matt Zimmerman (Debian UML maintainer) should take a
> > look at this.
>
> Yes, I ran into this problem when testing the 2.4.24-3um packages for
> Debian. With previous UMLs, hwclock would simply produce an error, and the
> process would continue, but with 2.4.24-3um, it seems to hang.  Any idea
> why this might be?

Not at all - there is a big bug in 2.4.24-3 with modules (any iptables user 
get crashes), and "rtc" is probably a module; that bug is fixed in 2.4.26-2, 
which has another critical bug on console I/O fixed in 2.4.26-3, which is 
safe (apart all the experimental work on humfs and hostfs, which make them 
break in multiple ways). By the way, I've not heard this with any other 
distro (on my own I've only a Slack 9.0 root fs), so a look to hwclock could 
be useful, maybe.

Also, check for Real Time Clock UML option (enabling/disabling - does it makes 
difference?).

Here you can find a splitout version of all the changes from 2.4.24-1, so that 
you can try multiple combination of them. On the page there is the link to 
patch-scripts, which you'll love for patch-kit management (they are the tools 
used for the -mm tree). Give also a read to "series" and "rawSeries", inside 
the patch-scripts folder.

The patch at fault for modules is "optimization-unstable.patch", which is 
reverted in "revert-optim-broken.patch".

http://www.user-mode-linux.org/~blaisorblade/patches/UML-splitout-2.4.26-2.tar.bz2

Bye
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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[uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Matt Zimmerman]

On Thu, Sep 09, 2004 at 09:33:35PM +0200, BlaisorBlade wrote:

> On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> > Yes, I ran into this problem when testing the 2.4.24-3um packages for
> > Debian. With previous UMLs, hwclock would simply produce an error, and the
> > process would continue, but with 2.4.24-3um, it seems to hang.  Any idea
> > why this might be?
> 
> Not at all - there is a big bug in 2.4.24-3 with modules (any iptables user 
> get crashes), and "rtc" is probably a module; that bug is fixed in 2.4.26-2, 
> which has another critical bug on console I/O fixed in 2.4.26-3, which is 
> safe (apart all the experimental work on humfs and hostfs, which make them 
> break in multiple ways). By the way, I've not heard this with any other 
> distro (on my own I've only a Slack 9.0 root fs), so a look to hwclock could 
> be useful, maybe.

hwclock has caused problems for UML in the past; one of the strange things
that it does is to try to open an fd for the console, because some
architectures use that as a means to interface to the hardware clock.

I ran hwclock under strace to find out where the hang was occurring, and
discovered that it succeeds when running under strace. :-(  Here's the output
anyway:

execve("/sbin/hwclock", ["/sbin/hwclock"], [/* 5 vars */]) = 0
uname({sys="Linux", node="(none)", ...}) = 0
brk(0)                                  = 0x80503f4
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=6093, ...}) = 0
old_mmap(NULL, 6093, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40014000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\30\222"..., 1024) = 1024
fstat64(3, {st_mode=S_IFREG|0755, st_size=1153784, ...}) = 0
old_mmap(NULL, 1166560, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40016000
mprotect(0x40129000, 40160, PROT_NONE)  = 0
old_mmap(0x40129000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x113000) = 0x40129000
old_mmap(0x4012f000, 15584, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4012f000
close(3)                                = 0
munmap(0x40014000, 6093)                = 0
gettimeofday({1094758887, 536067}, NULL) = 0
brk(0)                                  = 0x80503f4
brk(0x805041c)                          = 0x805041c
brk(0x8051000)                          = 0x8051000
getuid32()                              = 0
open("/dev/rtc", O_RDONLY|O_LARGEFILErequest_module[char-major-10-135]: fork failed, errno 1
)  = -1 ENODEV (No such device)
open("/dev/misc/rtc", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/dev/tty1", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, 0x4b50, 0x9ffffab8)            = -1 EINVAL (Invalid argument)
iopl(0x3)                               = -1 ENOSYS (Function not implemented)
write(2, "hwclock is unable to get I/O por"..., 68hwclock is unable to get I/O port access:  the iopl(3) call failed.
) = 68
_exit(0)                                = ?
bash-2.05a# /mnt/usr/bin/strace /sbin/hwclock
execve("/sbin/hwclock", ["/sbin/hwclock"], [/* 5 vars */]) = 0
uname({sys="Linux", node="(none)", ...}) = 0
brk(0)                                  = 0x80503f4
open("/etc/ld.so.preload", O_RDONLY)    = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=6093, ...}) = 0
old_mmap(NULL, 6093, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40014000
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\30\222"..., 1024) = 1024
fstat64(3, {st_mode=S_IFREG|0755, st_size=1153784, ...}) = 0
old_mmap(NULL, 1166560, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40016000
mprotect(0x40129000, 40160, PROT_NONE)  = 0
old_mmap(0x40129000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x113000) = 0x40129000
old_mmap(0x4012f000, 15584, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4012f000
close(3)                                = 0
munmap(0x40014000, 6093)                = 0
gettimeofday({1094758918, 176968}, NULL) = 0
brk(0)                                  = 0x80503f4
brk(0x805041c)                          = 0x805041c
brk(0x8051000)                          = 0x8051000
getuid32()                              = 0
open("/dev/rtc", O_RDONLY|O_LARGEFILErequest_module[char-major-10-135]: fork failed, errno 1
)  = -1 ENODEV (No such device)
open("/dev/misc/rtc", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/dev/tty1", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, 0x4b50, 0x9ffffab8)            = -1 EINVAL (Invalid argument)
iopl(0x3)                               = -1 ENOSYS (Function not implemented)
write(2, "hwclock is unable to get I/O por"..., 68hwclock is unable to get I/O port access:  the iopl(3) call failed.
) = 68
_exit(0)                                = ?

In the course of this test, I also noticed that it is not just hwclock which
hangs, but the entire UML.  Not even mconsole works after hwclock is run.

UML in Debian has been in bad shape for some time, after the hostfs
breakage, and then all the reports of hangs in tt mode
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=260111), and I would very
much like to get a stable version in soon.

FWIW, you can find a Debian UML image (which should easily reproduce this
problem) here:

http://people.debian.org/~mdz/uml/Debian-3.0r2.ext2.bz2

> Also, check for Real Time Clock UML option (enabling/disabling - does it makes 
> difference?).

Currently, it is using CONFIG_UML_REAL_TIME_CLOCK=y.  This has not changed
for some time:

1.40         (mdz      16-Dec-03): CONFIG_UML_REAL_TIME_CLOCK=y

> Here you can find a splitout version of all the changes from 2.4.24-1, so that 
> you can try multiple combination of them. On the page there is the link to 
> patch-scripts, which you'll love for patch-kit management (they are the tools 
> used for the -mm tree). Give also a read to "series" and "rawSeries", inside 
> the patch-scripts folder.

Thanks.  Unfortunately, I'm very busy with work, and I'm not sure when I
will have time to try all of these patches individually.  I can say,
however, that this problem did not exist for me when using skas with
2.4.24-2um.

-- 
 - mdz


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[BlaisorBlade]

On Thursday 09 September 2004 21:46, Matt Zimmerman wrote:
> On Thu, Sep 09, 2004 at 09:33:35PM +0200, BlaisorBlade wrote:
> > On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> > > Yes, I ran into this problem when testing the 2.4.24-3um packages for
> > > Debian. With previous UMLs, hwclock would simply produce an error, and
> > > the process would continue, but with 2.4.24-3um, it seems to hang.  Any
> > > idea why this might be?
> >

> UML in Debian has been in bad shape for some time, after the hostfs
> breakage, and then all the reports of hangs in tt mode
> (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=260111), and I would very
> much like to get a stable version in soon.

Please, update to 2.4.26-3. That has the fix! And it's not tt mode related. If 
you don't want the full upgrade, the tarball contains already the fix, which 
is move-generic_console_write-back.patch.

Bye
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[BlaisorBlade]

On Thursday 09 September 2004 21:46, Matt Zimmerman wrote:
> On Thu, Sep 09, 2004 at 09:33:35PM +0200, BlaisorBlade wrote:
> > On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> > > Yes, I ran into this problem when testing the 2.4.24-3um packages for
> > > Debian. With previous UMLs, hwclock would simply produce an error, and
> > > the process would continue, but with 2.4.24-3um, it seems to hang.  Any
> > > idea why this might be?
> >
> > Not at all - there is a big bug in 2.4.24-3 with modules (any iptables
> > user get crashes), and "rtc" is probably a module; that bug is fixed in
> > 2.4.26-2, which has another critical bug on console I/O fixed in
> > 2.4.26-3, which is safe (apart all the experimental work on humfs and
> > hostfs, which make them break in multiple ways). By the way, I've not
> > heard this with any other distro (on my own I've only a Slack 9.0 root
> > fs), so a look to hwclock could be useful, maybe.
>
> hwclock has caused problems for UML in the past; one of the strange things
> that it does is to try to open an fd for the console, because some
> architectures use that as a means to interface to the hardware clock.
>
> I ran hwclock under strace to find out where the hang was occurring, and
> discovered that it succeeds when running under strace. :-(  Here's the
> output anyway:

> In the course of this test, I also noticed that it is not just hwclock
> which hangs, but the entire UML.  Not even mconsole works after hwclock is
> run.

> UML in Debian has been in bad shape for some time, after the hostfs
> breakage, and then all the reports of hangs in tt mode
> (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=260111), and I would very
> much like to get a stable version in soon.
Well, I might do a proper patch choosing and release a 2.4.26 (or 2.4.27 - 
hope the patch shouldn't change) without any hostfs change and without known 
bugs (at least I hope).

> FWIW, you can find a Debian UML image (which should easily reproduce this
> problem) here:
>
> http://people.debian.org/~mdz/uml/Debian-3.0r2.ext2.bz2
No broadband, sorry. The only fs I downloaded is the root_fs_tomsbrt, i.e. 
1,4Mega wide IIRC.
> > Also, check for Real Time Clock UML option (enabling/disabling - does it
> > makes difference?).
>
> Currently, it is using CONFIG_UML_REAL_TIME_CLOCK=y.  This has not changed
> for some time:
>
> 1.40         (mdz      16-Dec-03): CONFIG_UML_REAL_TIME_CLOCK=y
If you get any difference by disabling it, let me know.

-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Matt Zimmerman]

On Thu, Sep 09, 2004 at 10:06:35PM +0200, BlaisorBlade wrote:

> On Thursday 09 September 2004 21:46, Matt Zimmerman wrote:
> > On Thu, Sep 09, 2004 at 09:33:35PM +0200, BlaisorBlade wrote:
> > > On Thursday 09 September 2004 20:49, Matt Zimmerman wrote:
> > > > Yes, I ran into this problem when testing the 2.4.24-3um packages for
> > > > Debian. With previous UMLs, hwclock would simply produce an error, and
> > > > the process would continue, but with 2.4.24-3um, it seems to hang.  Any
> > > > idea why this might be?
> > >
> 
> > UML in Debian has been in bad shape for some time, after the hostfs
> > breakage, and then all the reports of hangs in tt mode
> > (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=260111), and I would very
> > much like to get a stable version in soon.
> 
> Please, update to 2.4.26-3. That has the fix! And it's not tt mode related. If 
> you don't want the full upgrade, the tarball contains already the fix, which 
> is move-generic_console_write-back.patch.

I already have; it should be in unstable now.  However, it has this new bug
with hwclock which is just as bad for Debian users.

-- 
 - mdz


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Adam Heath]

On Thu, 9 Sep 2004, Matt Zimmerman wrote:

> hwclock has caused problems for UML in the past; one of the strange things
> that it does is to try to open an fd for the console, because some
> architectures use that as a means to interface to the hardware clock.

hwclock shouldn't be doing that.  It does it on all archs, even if the current
doesn't require it, just because some arch *may* require it.

But, obviously, whatever hwclock doesn't, shouldn't break uml.


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Matt Zimmerman]

On Fri, Sep 10, 2004 at 01:04:04AM -0400, Jeff Dike wrote:

> mdz@debian.org said:
> > FWIW, you can find a Debian UML image (which should easily reproduce
> > this problem) here:
> >
> > http://people.debian.org/~mdz/uml/Debian-3.0r2.ext2.bz2 
> 
> I just tried it with my current UML, and it works fine:
> 
> 	Setting the System Clock using the Hardware Clock as reference...
> 	hwclock is unable to get I/O port access:  the iopl(3) call failed.
> 	System Clock set. System local time is now Fri Sep 10 03:58:17 UTC 2004.

In tt mode?

-- 
 - mdz


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Jeff Dike]

mdz@debian.org said:
> FWIW, you can find a Debian UML image (which should easily reproduce
> this problem) here:
>
> http://people.debian.org/~mdz/uml/Debian-3.0r2.ext2.bz2 

I just tried it with my current UML, and it works fine:

	Setting the System Clock using the Hardware Clock as reference...
	hwclock is unable to get I/O port access:  the iopl(3) call failed.
	System Clock set. System local time is now Fri Sep 10 03:58:17 UTC 2004.

				Jeff


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Geert Uytterhoeven]

On Thu, 9 Sep 2004, Matt Zimmerman wrote:
> hwclock has caused problems for UML in the past; one of the strange things
> that it does is to try to open an fd for the console, because some
> architectures use that as a means to interface to the hardware clock.

> open("/dev/rtc", O_RDONLY|O_LARGEFILErequest_module[char-major-10-135]: fork failed, errno 1

If UML would implement /dev/rtc, hwclock would never get to here:

> open("/dev/tty1", O_RDONLY|O_LARGEFILE) = 3

This is just done for backwards-compatibility. /dev/rtc is the way to go.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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Re: [uml-devel] Re: [uml-user] UML hanging at "Activating swap"

[Jeff Dike]

mdz@debian.org said:
> In tt mode? 

Yup.


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