Re: [uml-user] MySQL/PHP/Apache kills UML

[Matt C. <ma...@co...>]

Jeff Dike wrote:
>
> Had the kernel paniced when you got the backtrace?  If so, that thread should
> have been in the middle of panic.

Yes, the kernel had already paniced by this point.  I get this on the
console:

Kernel panic: Kernel mode fault at addr 0x0, ip 0x1006ab71
In interrupt handler - not syncing 

> In any case, this looks pretty bogus:
> 
> #4  0x1009534c in segv (address=8, ip=268849158, is_write=2, is_user=0)
>     at trap_kern.c:66
> 
> Can you do an 'i sym <addr>' and 'i line *<addr>' where <addr> is whatever is
> in the ip argument of segv?

I ran it again, same problem, just a longer backtrace.  I've left this
one running, so if you need more information, I can still enter more
commands into debug.  Anyways, here's my debug session so far with the
extra information you asked for:

2000009
att 1
b start_kernel
c
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This GDB was configured as "i686-pc-linux-gnu"...
(gdb) att 1
Attaching to program: /home/uml/umlDev/linux, process 1
0x1009c001 in __kill ()
(gdb) b start_kernel
Breakpoint 1 at 0x100d8f1b: file init/main.c, line 515.
(gdb) c
Continuing.

Breakpoint 1, start_kernel () at init/main.c:515
515             printk(linux_banner);
(gdb) c
Continuing.

Program received signal SIGINT, Interrupt.
0x1009bf76 in __sigprocmask (how=1, set=0x5f6bb878, oset=0x0)
    at ../sysdeps/unix/sysv/linux/sigprocmask.c:49
49      ../sysdeps/unix/sysv/linux/sigprocmask.c: No such file or
directory.
(gdb) backtrace
#0  0x1009bf76 in __sigprocmask (how=1, set=0x5f6bb878, oset=0x0)
    at ../sysdeps/unix/sysv/linux/sigprocmask.c:49
#1  0x10091411 in change_sig (signal=10, on=1) at process.c:218
#2  0x10094785 in timer_handler (sig=26) at time_kern.c:32
#3  0x1009bf38 in __restore ()
    at ../sysdeps/unix/sysv/linux/i386/sigaction.c:125
#4  0x1009534c in segv (address=0, ip=268872561, is_write=2, is_user=0)
    at trap_kern.c:66
#5  0x10095c04 in segv_handler (sig=11) at trap_user.c:285
#6  0x1009bf38 in __restore ()
    at ../sysdeps/unix/sysv/linux/i386/sigaction.c:125
#7  0x10066c91 in dev_queue_xmit (skb=0x5fe152f0) at dev.c:908
#8  0x1007035e in ip_output (skb=0x5fe152f0) at ip_output.c:172
#9  0x1007071e in ip_queue_xmit (skb=0x5fe152f0) at ip_output.c:316
#10 0x1007c2ea in tcp_transmit_skb (sk=0x5f2bdcc0, skb=0x5fe152f0)
    at tcp_output.c:282
#11 0x1007c4bb in tcp_send_skb (sk=0x5f2bdcc0, skb=0x5ea30ca0,
force_queue=0,
    cur_mss=1448) at tcp_output.c:321
#12 0x100740ec in tcp_sendmsg (sk=0x5f2bdcc0, msg=0x5f6bbda4, size=4110)
    at tcp.c:1091
#13 0x1008983a in inet_sendmsg (sock=0x5fd6548c, msg=0x5f6bbda4,
size=4110,
    scm=0x5f6bbd74) at af_inet.c:748
#14 0x10062064 in sock_sendmsg (sock=0x5fd6548c, msg=0x5f6bbda4,
size=4110)
---Type <return> to continue, or q <return> to quit---
    at socket.c:508
#15 0x100622df in sock_readv_writev (type=0, inode=0x5fd653a0,
    file=0x5f5b0cc0, iov=0x5f6bbe30, count=2, size=4110) at socket.c:628
#16 0x1006235f in sock_writev (file=0x5f5b0cc0, vector=0x5f6bbe30,
count=2,
    ppos=0x5f5b0ce0) at socket.c:649
#17 0x1001ff7c in do_readv_writev (type=0, file=0x5f5b0cc0,
vector=0xbf7fd2fc,
    count=2) at read_write.c:232
#18 0x100200f2 in sys_writev (fd=3, vector=0xbf7fd2fc, count=2)
    at read_write.c:307
#19 0x10093d02 in execute_syscall (syscall=146, args=0x5f6bbef8)
    at syscall_kern.c:340
#20 0x100940f8 in syscall_handler (unused=0) at syscall_user.c:113
#21 0x100910ab in fork_handler (sig=10) at process.c:97
#22 0x1009bf38 in __restore ()
    at ../sysdeps/unix/sysv/linux/i386/sigaction.c:125
(gdb) i sym 268872561
pfifo_fast_enqueue + 61 in section .text
(gdb) i line *268872561
Line 462 of "/home/uml/shared/linux/include/linux/skbuff.h"
   starts at address 0x1006ab71 <pfifo_fast_enqueue+61>
   and ends at 0x1006ab73 <pfifo_fast_enqueue+63>.
(gdb)

 - Matt