[Haifux] Login console freezes: Eli's weekly riddle

Eli Billauer eli at billauer.co.il
Fri Oct 29 11:54:55 MSD 2010


Even though it would be fun (??!!) to dig into the authentication 
mechanism, isn't the fact that failing to open /dev/tty takes 30 seconds 
enough to blame the kernel alone? Or the same time to open /dev/pts/0? 
Could there be any explanation for this except for a kernel bug?

And yes, I'm using Fedora 12 with a 2.6.36 vanilla kernel. I'm a wild 
guy. But so was my 2.6.35, which has no particular problems, except for 
what happens when the disk is accessed heavily. So the freeze thing lies 
in what happened in the gap between two vanillas.

And as a side remark, I've had two null pointer oopses when logging out 
the GUI console. The caller seems to be 
selinux_socket_unix_stream_connect(). Oopses. I think I'm going to post 
a kernel patch which paints the screen background blue.

My current standpoint is that I've seen enough to know who to blame, and 
that leaves me with the possibility to post a kernel bug report (unless 
someone tells me I'll make a fool of myself doing so) or just wait until 
a kernel patch emerges. As I logout or boot very rarely, I can live with 
this issue for a month or two. Please correct me if I'm wrong.



Shachar Shemesh wrote:

> On 28/10/10 17:59, Eli Billauer wrote:
>> Hi,
>> PAM did indeed cross my mind as a suspect. Unfortunately, I have no 
>> /var/log/auth* logfiles. As a matter of fact, I don't have any log 
>> messages related to authentication. In my very old Redhat 7.3, I had 
>> pam_unix messages in /var/log/messages telling me who has changed 
>> user ID. On Fedora 12, nothing is mentioned about becoming root in 
>> /var/log/messages, and I can't see any directory or file in /var/log 
>> that seems to contain that information. Maybe under the audit 
>> directory, but the files there are not really human readable.
> Just some random thought - perchance the two are not independent? 
> Maybe you have a PAM configuration problems that causes both the lack 
> of logs AND the slow login?
> Also, did you try public key authentication via ssh to see whether 
> that one is faster?
>> Any idea of where my authenticate mechanism keeps its logs?
> Should probably have been "where your authentication mechanism keeps 
> the config files that tell it where to generate the logs". Give a man 
> a fish, and he'll eat for a day. Teach him how to cook, and he'll die 
> starving, dreaming of all the wonderful things he could have cooked, 
> had only he had a fish....
>> And why a kernel upgrade would have any effect?
> Like I said. I suspect the configuration was broken even before the 
> upgrade.
>> <rant>In the past, I clearly recall just upgrading my kernel and all 
>> was fine. Where are those days?</rant>
> I'm sorry, you mistagged the above. We employ a strict four pages 
> minimum on rants. Soap box addresses between one and four pages should 
> carry the "bicker" tag. Complaints over two lines long should carry 
> the "hidepark" tag. This two sentences should have carried the "whine" 
> tag.
> <whine>There used to be a time when you could expect old timers to 
> read the list's FAQ....</whine>
> Shachar
> P.s.
> You did say "Fedora 12", as in "RedHat based distribution", as in 
> "tons and tons of patches over the vanilla kernel", right? What kernel 
> did you upgrade to? Was it vanilla?
> Sh.

Web: http://www.billauer.co.il

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