Bug#546609: xserver-xorg: Blank screen if switching from vt7 to vt1 and back to vt7, after kdm login

[Boris shtrasman]

Brice Goglin wrote:
> Boris shtrasman wrote:
>> Package: xserver-xorg
>> Version: 1:7.4+4
>> Severity: critical
>> Justification: breaks the whole system
>>
>> Happen starting from 7.4 (i tested it with 7.3 where it didn't happen).
>> Happens only after login to kdm / gdm :
>> Tested before login works as a charm.
>> after kde login if i switch to any non graphical vt (1-6) and then back
>> to vt7 i got blank screen.
>> sysrq+k/b dosn't work (no affect).
>> alt+ctrl+del also dosn't work
>>
>> nothing that i can do except manually shutdown down the pc (power button).
>>
>
> Can you ping the machine from another machine ? If so, can you log in
> through ssh and attach a gdb to see what the server is doing?
>
> Brice
>
I don't know if it worth anything but this is what i got :

[Thread debugging using libthread_db enabled]
0x00007f503ffd9eb3 in select () from /lib/libc.so.6

Thread 1 (Thread 0x7f5042495790 (LWP 5314)):
#0  0x00007f503ffd9eb3 in select () from /lib/libc.so.6
#1  0x00000000004ebbcb in WaitForSomething (pClientsReady=0x27a1680)
at ../../os/WaitFor.c:228
#2  0x000000000044d060 in Dispatch () at ../../dix/dispatch.c:367
#3  0x000000000043329a in main (argc=8, argv=0x7fff1486b318,
envp=<value optimized out>) at ../../dix/main.c:397
[Thread debugging using libthread_db enabled]
0x00007f503ffd9eb3 in select () from /lib/libc.so.6

Thread 1 (Thread 0x7f5042495790 (LWP 5314)):
#0  0x00007f503ffd9eb3 in select () from /lib/libc.so.6
#1  0x00000000004ebbcb in WaitForSomething (pClientsReady=0x27a1680)
at ../../os/WaitFor.c:228
#2  0x000000000044d060 in Dispatch () at ../../dix/dispatch.c:367
#3  0x000000000043329a in main (argc=8, argv=0x7fff1486b318,
envp=<value optimized out>) at ../../dix/main.c:397
[Thread debugging using libthread_db enabled]
0x00007f503ffd9eb3 in select () from /lib/libc.so.6

Thread 1 (Thread 0x7f5042495790 (LWP 5314)):
#0  0x00007f503ffd9eb3 in select () from /lib/libc.so.6
#1  0x00000000004ebbcb in WaitForSomething (pClientsReady=0x27a1680)
at ../../os/WaitFor.c:228
#2  0x000000000044d060 in Dispatch () at ../../dix/dispatch.c:367
#3  0x000000000043329a in main (argc=8, argv=0x7fff1486b318,
envp=<value optimized out>) at ../../dix/main.c:397
[Thread debugging using libthread_db enabled]
0x00007f503ffd9eb3 in select () from /lib/libc.so.6

Thread 1 (Thread 0x7f5042495790 (LWP 5314)):
#0  0x00007f503ffd9eb3 in select () from /lib/libc.so.6
#1  0x00000000004ebbcb in WaitForSomething (pClientsReady=0x27a1680)
at ../../os/WaitFor.c:228
#2  0x000000000044d060 in Dispatch () at ../../dix/dispatch.c:367
#3  0x000000000043329a in main (argc=8, argv=0x7fff1486b318,
envp=<value optimized out>) at ../../dix/main.c:397
[Thread debugging using libthread_db enabled]
0x00007f503ffd9eb3 in select () from /lib/libc.so.6

Thread 1 (Thread 0x7f5042495790 (LWP 5314)):
#0  0x00007f503ffd9eb3 in select () from /lib/libc.so.6
#1  0x00000000004ebbcb in WaitForSomething (pClientsReady=0x27a1680)
at ../../os/WaitFor.c:228
#2  0x000000000044d060 in Dispatch () at ../../dix/dispatch.c:367
#3  0x000000000043329a in main (argc=8, argv=0x7fff1486b318,
envp=<value optimized out>) at ../../dix/main.c:397
did it by :
screen

#!/bin/bash
nsamples=20;
pid=`ps aux | grep X | grep -vvv grep | cut -d" " -f7`
for x in $( seq 0 $nsamples) ; do

gdb -ex "set pagination 0" -ex "thread apply all bt" --batch
/usr/lib/debug/usr/bin/Xorg $pid | tee -a tests

sleep 15
done

i was trying to go to diffrent vt during that time one finally i gave
up and restarted the pc

now i'm pretty sure you need more data but what should i do more ?