[uml-devel] UML crashing

[uml-devel] UML crashing

[Thomas Schwinge]

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Hello!

Since my current UML (linux-2.6.3 with uml-patch-2.6.3-rc2-1.bz2 and
<URL:http://www.metaparadigm.com/~mclark/uml/uml-2.6.3-skas-1.patch>)
is crashing reproducibly I wanted to provide you with a backtrace but
that won't work.

The host's kernel was build from the same sources; I'be been running UML
in skas mode.

Previously I was running a kernel without debugging symbols etc. - after
anabling these for the guest's kernel (see the attached .config) I got
this while booting:
#v+
kernel/sched.c:1516: spin_lock(kernel/sched.c:a03703c0) already locked by kernel/sched.c/1637
kernel/sched.c:876: spin_unlock(kernel/sched.c:a03703c0) not locked
[...]
kernel/sched.c:1516: spin_lock(kernel/sched.c:a03703c0) already locked by kernel/sched.c/1637
kernel/sched.c:876: spin_unlock(kernel/sched.c:a03703c0) not locked
[...]
kernel/sched.c:291: spin_lock(kernel/sched.c:a03703c0) already locked by kernel/sched.c/1637
#v-

([...] was the boot scripts' output.)

When e.g. trying to compile a certain software package UML crashes:
#v+
Kernel panic: kernel BUG at kernel/exit.c:793!

 <6>SysRq : Show Regs

EIP: 0073:[<400a0137>] CPU: 0 Not tainted ESP: 007b:bffff4d0 EFLAGS: 00000246
    Not tainted
EAX: ffffffda EBX: 00000000 ECX: 00000000 EDX: 00000000
ESI: 4010aaac EDI: 00000000 EBP: bffff4e4 DS: 007b ES: 007b
Call Trace: [<a003a2d3>] [<a01283c7>] [<a01283af>] [<a0128348>] [<a0128334>] 
   [<a001de62>] [<a003a2c1>] [<a003a2d3>] [<a004d0ca>] [<a0115e57>] [<a003a2d3>] 
   [<a0039318>] [<a0039304>] [<a00392fa>] [<a003d202>] [<a003ce64>] [<a001cc43>] 
   [<a00174d1>] [<a001cfac>] [<a003d45e>] [<a001d055>] [<a001d136>] [<a003d476>] 
   [<a0023b25>] [<a001bc93>] [<a001be5b>] [<a0023b6c>] [<a0023b63>] [<a0022e14>] 
   [<a002304a>] [<a0031f4f>] [<a001b124>] [<a002386a>] [<a0023852>] [<a01cad68>] 
   [<a0031f4f>] [<a01cbe7d>] 
#v-

I tried to rerun UML using gdb:
#v+
GNU gdb 6.0
Copyright 2003 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
---Type <return> to continue, or q <return> to quit---
This GDB was configured as "i686-pc-linux-gnu"...
(gdb) handle SIGSEGV pass nostop noprint
Signal        Stop      Print   Pass to program Description
SIGSEGV       No        No      Yes             Segmentation fault
(gdb) handle SIGUSR1 pass nostop noprint
Signal        Stop      Print   Pass to program Description
SIGUSR1       No        No      Yes             User defined signal 1
(gdb) break panic
Breakpoint 1 at 0xa003927b: file kernel/panic.c, line 59.
(gdb) break exit
Breakpoint 2 at 0xa01c3b64
(gdb) r
Starting program: /fs/hda2/mount/home/thomas/command/linux-debug mem=64M con=xterm init=/command/runit ubd0=/dev/mapper/VGhda-uml ubd1=/dev/mapper/VGhda-uml_LVM eth0=tuntap,tun1,fe:fd:0:0:0:2 ip=dhcp umid=uml
#v-

After some time of compiling I got the following and the kernel froze:
#v+
Kernel panic: Kernel mode fault at addr 0x94, ip 0x401070a5
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
Kernel panic: Kernel mode fault at addr 0x0, ip 0x40106b8f
In idle task - not syncing
#v-

I was not able to 'STRG-C' gdb and get a backtrace - it was also frozen.

After killing the UML processes I was able to get get the following in gdb:
#v+
Program received signal SIGTERM, Terminated.
---Type <return> to continue, or q <return> to quit---
0xa01cb032 in sigprocmask ()
(gdb) Quit
(gdb) bt
#0  0xa01cb032 in sigprocmask ()
#1  0xa001b05f in change_sig (signal=10, on=1) at arch/um/kernel/signal_user.c:56
#2  0xa0024024 in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:29
#3  0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#4  <signal handler called>
#5  free_block (cachep=0xa3ff8d80, objpp=0xa3fde2f8, nr_objects=16) at include/linux/list.h:135
---Type <return> to continue, or q <return> to quit---
#6  0xa0064e97 in cache_flusharray (cachep=0xa3ff8d80, ac=0xa3fde2e8) at mm/slab.c:2010
#7  0xa0065623 in kmem_cache_free (cachep=0xa3ff8d80, objp=2756) at mm/slab.c:2056
#8  0xa005e9a2 in mempool_free_slab (element=0xa0c70ac4, pool_data=0xa3ff8d80) at mm/mempool.c:286
#9  0xa005e964 in mempool_free (element=0xa0c70ac4, pool=0xa3f98a78) at mm/mempool.c:269
#10 0xa012dcba in __blk_put_request (q=<error type>, req=<error type>) at drivers/block/ll_rw_blk.c:1473
#11 0xa012eead in end_that_request_last (req=<error type>) at drivers/block/ll_rw_blk.c:2606
---Type <return> to continue, or q <return> to quit---
#12 0xa012ef49 in end_request (req=<error type>, uptodate=1) at drivers/block/ll_rw_blk.c:2619
#13 0xa002875b in ubd_finish (req=<incomplete type>, error=0) at arch/um/drivers/ubd_kern.c:416
#14 0xa00289ca in ubd_handler () at arch/um/drivers/ubd_kern.c:451
#15 0xa00289ff in ubd_intr (irq=4, dev=0xa02a31a0, unused=0xa0c50b24) at arch/um/drivers/ubd_kern.c:458
#16 0xa0014bb6 in handle_IRQ_event (irq=4, regs=0xa0c50b24, action=
        {task = 0xa3fffd08, type = -1597509676, op = {proc_get_link = 0xa3ffda18, proc_read = 0xa3ffda18}, pde = 0xa3ffd428, vfs_inode = {d_count = {size = ---Type <return> to continue, or q <return> to quit---
2697268004, sect = 232, head = 2697268004, track = 2751462664, stretch = 2697457668, gap = 20 '\024', rate = 92 '\\', spec1 = 1 '\001', fmt_gap = 160 ' ', name = 0x4 <Address 0x4 out of bounds>}, d_vfs_flags = 232, d_lock = {fn = 0xa0c50b24, arg0 = 2751462664, arg1 = 2697457668, arg2 = 2684443668, arg3 = 4}, d_inode = 0x0, d_lru = {next = 0xa0015ba1, prev = 0xe8}, d_child = {next = 0xa0c50b24, prev = 0xa0000094}, d_subdirs = {next = 0x0, prev = 0x0}, d_alias = {next = 0x0, prev = 0xa0c7f034}, d_time = 2684502091, d_op = 0x1d, d_sb = 0xa0c50b24, d_flags = 2697457716, d_mounted = -1610465299, d_fsdata = 0x1, d_rcu = <incomplete type>, d_cookie = 0x16, d_move_count = 2697457748, d_qstr = 0xa001d7be, d_parent = 0x1d, d_name = {list = {next = 0xa0c7f060, prev = 0x5a5a5a5a}, func = 0x5a5a5a5a, arg = 0x5a5a5a5a}, d_hash = {next = 0x5a5a5a5a, pprev = 0x5a5a5a5a}, d_bucket = 0xa0c7f34c, d_iname = "h­\034 \035\000\000\000\000\000\00---Type <return> to continue, or q <return> to quit---
0\000\000\000\000"}}) at arch/um/kernel/irq.c:155
#17 0xa001500d in do_IRQ (irq=4, regs=0xa0c50b24) at arch/um/kernel/irq.c:327
#18 0xa0015c14 in sigio_handler (sig=29, regs=0xa0c50b24) at arch/um/kernel/irq_user.c:73
#19 0xa002404b in sig_handler_common_skas (sig=29, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#20 0xa001d7be in sig_handler (sig=29, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#21 <signal handler called>
---Type <return> to continue, or q <return> to quit---
#22 0xa01cb032 in sigprocmask ()
#23 0xa001b0d8 in change_signals (type=1) at arch/um/kernel/signal_user.c:69
#24 0xa001b124 in unblock_signals () at arch/um/kernel/signal_user.c:80
#25 0xa002403b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:31
#26 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#27 <signal handler called>
---Type <return> to continue, or q <return> to quit---
#28 0xa003a47a in release_console_sem () at kernel/printk.c:603
#29 0xa003a2d3 in printk (fmt=0xa0227b60 "<3>Slab corruption: start=%p, expend=%p, problemat=%p\n") at kernel/printk.c:543
#30 0xa0062f1b in check_poison_obj (cachep=0xa0800c80, objp=57648) at mm/slab.c:916
#31 0xa006524f in __kmalloc (size=
      {kset = {subsys = 0x6a0, ktype = 0x20, list = {debugregs = {5, 2684512258, 2751206560, 2751207168, 5, 2684505219, 2708110512, 2708110840}, debugregs_seq = -1597507500}, kobj = 2751206560, hotplug_ops = 0xa3fc14a0}, rwsem = <error type>}, flags=32) at mm/slab.c:1876
---Type <return> to continue, or q <return> to quit---
#32 0xa0143636 in alloc_skb (size=1516, gfp_mask=32) at include/linux/slab.h:97
#33 0xa0024b8f in uml_net_rx (dev=<incomplete type>) at include/linux/skbuff.h:1059
#34 0xa0024d5b in uml_net_interrupt (irq=5, dev_id=0xa3fc14a0, regs=0xa0c50b24) at arch/um/drivers/net_kern.c:76
#35 0xa0014bb6 in handle_IRQ_event (irq=5, regs=0xa0c50b24, action=
        {task = 0xa03a8c00, type = -1597507356, op = {proc_get_link = 0xa3ffd428, proc_read = 0xa3ffd428}, pde = 0xa3ffd6d4, vfs_inode = {d_count = {size = 2697268004, sect = 232, head = 2697268004, track = 2688191488, stretch = 2697459988, gap = 20 '\024', rate = 92 '\\', spec1 = 1 '\001', fmt_gap = 160 ' ', n---Type <return> to continue, or q <return> to quit---
ame = 0x5 <Address 0x5 out of bounds>}, d_vfs_flags = 232, d_lock = {fn = 0xa0c50b24, arg0 = 2688191488, arg1 = 2697459988, arg2 = 2684443668, arg3 = 5}, d_inode = 0x0, d_lru = {next = 0xa0015ba1, prev = 0xe8}, d_child = {next = 0xa0c50b24, prev = 0xa0000094}, d_subdirs = {next = 0x0, prev = 0x0}, d_alias = {next = 0x0, prev = 0xa0c7f944}, d_time = 2684502091, d_op = 0x1d, d_sb = 0xa0c50b24, d_flags = 2697460036, d_mounted = -1610465299, d_fsdata = 0x1, d_rcu = <incomplete type>, d_cookie = 0x2, d_move_count = 2697460068, d_qstr = 0xa001d7be, d_parent = 0x1d, d_name = {list = {next = 0xa0c7f970, prev = 0xa0c7f974}, func = 0xa001d7dc <alarm_handler+24>, arg = 0xa0c7fd0c}, d_hash = {next = 0xa0c7fd0c, pprev = 0x0}, d_bucket = 0xa0c7fc5c, d_iname = "h­\034 \035\000\000\000\000\000\000\000\000\000\000"}}) at arch/um/kernel/irq.c:155
---Type <return> to continue, or q <return> to quit---
#36 0xa001500d in do_IRQ (irq=5, regs=0xa0c50b24) at arch/um/kernel/irq.c:327
#37 0xa0015c14 in sigio_handler (sig=29, regs=0xa0c50b24) at arch/um/kernel/irq_user.c:73
#38 0xa002404b in sig_handler_common_skas (sig=29, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#39 0xa001d7be in sig_handler (sig=29, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#40 <signal handler called>
#41 0xa01cb032 in sigprocmask ()
---Type <return> to continue, or q <return> to quit---
#42 0xa001b05f in change_sig (signal=10, on=1) at arch/um/kernel/signal_user.c:56
#43 0xa0024024 in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:29
#44 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#45 <signal handler called>
#46 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#47 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#48 <signal handler called>
#49 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#50 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#51 <signal handler called>
#52 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#53 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#54 <signal handler called>
#55 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#56 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#57 <signal handler called>
#58 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#59 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#60 <signal handler called>
#61 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#62 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#63 <signal handler called>
#64 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#65 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
[repeating]
#168 <signal handler called>
#169 handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c88034) at arch/um/kernel/trap_kern.c:32
#170 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#171 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#172 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#173 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#174 <signal handler called>
#175 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#176 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c884ec) at include/linux/rwsem.h:45
#177 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#178 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#179 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
---Type <return> to continue, or q <return> to quit---
#180 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#181 <signal handler called>
#182 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#183 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c889a4) at include/linux/rwsem.h:45
#184 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#185 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
---Type <return> to continue, or q <return> to quit---
#186 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#187 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#188 <signal handler called>
#189 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#190 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c88e5c) at include/linux/rwsem.h:45
#191 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
---Type <return> to continue, or q <return> to quit---
#192 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#193 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#194 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#195 <signal handler called>
#196 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#197 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c89314) at include/linux/rwsem.h:45
---Type <return> to continue, or q <return> to quit---
#198 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#199 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#200 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#201 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#202 <signal handler called>
#203 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
---Type <return> to continue, or q <return> to quit---
#204 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c897cc) at include/linux/rwsem.h:45
#205 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#206 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#207 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#208 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#209 <signal handler called>
---Type <return> to continue, or q <return> to quit---
#210 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#211 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c89c84) at include/linux/rwsem.h:45
#212 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#213 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#214 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#215 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#216 <signal handler called>
#217 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#218 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8a13c) at include/linux/rwsem.h:45
#219 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#220 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#221 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
---Type <return> to continue, or q <return> to quit---
#222 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#223 <signal handler called>
#224 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#225 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8a5f4) at include/linux/rwsem.h:45
#226 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#227 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
---Type <return> to continue, or q <return> to quit---
#228 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#229 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#230 <signal handler called>
#231 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#232 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8aaac) at include/linux/rwsem.h:45
#233 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
---Type <return> to continue, or q <return> to quit---
#234 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#235 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#236 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#237 <signal handler called>
#238 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#239 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8af64) at include/linux/rwsem.h:45
---Type <return> to continue, or q <return> to quit---
#240 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#241 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#242 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#243 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#244 <signal handler called>
#245 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
---Type <return> to continue, or q <return> to quit---
#246 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8b41c) at include/linux/rwsem.h:45
#247 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#248 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#249 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#250 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#251 <signal handler called>
---Type <return> to continue, or q <return> to quit---
#252 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#253 0xa001ce35 in handle_page_fault (address=23786728, ip=1711436802, is_write=0, is_user=0, code_out=0xa0c8b8d4) at include/linux/rwsem.h:45
#254 0xa001d136 in segv (address=23786728, ip=1711436802, is_write=0, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#255 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#256 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
#257 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
---Type <return> to continue, or q <return> to quit---
#258 <signal handler called>
#259 __down_read (sem=0x16af4e4) at lib/rwsem-spinlock.c:127
#260 0xa001ce35 in handle_page_fault (address=1431636759, ip=1711436802, is_write=2, is_user=0, code_out=0xa0c8bd8c) at include/linux/rwsem.h:45
#261 0xa001d136 in segv (address=1431636759, ip=1711436802, is_write=2, is_user=0, sc=0xa001db1e) at arch/um/kernel/trap_kern.c:152
#262 0xa001d762 in segv_handler (sig=11, regs=0xa001db1e) at arch/um/kernel/trap_user.c:67
#263 0xa002404b in sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:33
---Type <return> to continue, or q <return> to quit---
#264 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#265 <signal handler called>
#266 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#267 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#268 <signal handler called>
#269 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
---Type <return> to continue, or q <return> to quit---
#270 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#271 <signal handler called>
#272 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#273 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#274 <signal handler called>
#275 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
---Type <return> to continue, or q <return> to quit---
#276 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#277 <signal handler called>
#278 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#279 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#280 <signal handler called>
#281 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
---Type <return> to continue, or q <return> to quit---
#282 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#283 <signal handler called>
#284 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#285 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#286 <signal handler called>
#287 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
---Type <return> to continue, or q <return> to quit---
#288 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#289 <signal handler called>
#290 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
#291 0xa001d7be in sig_handler (sig=11, sc=<incomplete type>) at arch/um/kernel/trap_user.c:101
#292 <signal handler called>
#293 sig_handler_common_skas (sig=11, sc_ptr=<incomplete type>) at arch/um/kernel/skas/trap_user.c:24
[repeating at least to #4000 when I left gdb...]
#v-

Repeating the whole story UML crashed again, the kernel and gdb told me:
#v+
Kernel panic: kernel BUG at kernel/exit.c:793!

 <6>SysRq : Show Regs

EIP: 0073:[<400a0137>] CPU: 0 Not tainted ESP: 007b:bffff4bc EFLAGS: 00000246
    Not tainted
EAX: ffffffda EBX: 00000000 ECX: 00000000 EDX: 00000000
ESI: 4010aaac EDI: 00000000 EBP: bffff4d0 DS: 007b ES: 007b
Call Trace: [<a003a2d3>] [<a01283c7>] [<a01283af>] [<a0128348>] [<a0128334>] 
   [<a001de62>] [<a003a2c1>] [<a003a2d3>] [<a004d0ca>] [<a0115e57>] [<a003a2d3>] 
   [<a0039318>] [<a0039304>] [<a00392fa>] [<a003d202>] [<a003ce64>] [<a001cc43>] 
   [<a00174d1>] [<a001cfac>] [<a003d45e>] [<a001d055>] [<a006fb96>] [<a001d136>] 
   [<a003d476>] [<a0023b25>] [<a001bc93>] [<a001be5b>] [<a0023b6c>] [<a0023b63>] 
   [<a0022e14>] [<a002304a>] [<a0031f4f>] [<a001b124>] [<a002386a>] [<a0023852>] 
   [<a01cad68>] [<a0031f4f>] [<a01cbe7d>] 


Program exited normally.
(gdb) bt
No stack.
#v-

So, the breakpoint at exit seems not to be working.
Since I am new in using a debugger I have to be told what to do now. :-)


Regards,
 Thomas

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Re: [uml-devel] UML crashing-the known scheduler bug

[BlaisorBlade]

Alle 19:51, giovedì 11 marzo 2004, Thomas Schwinge ha scritto:
> Hello!
>
> Since my current UML (linux-2.6.3 with uml-patch-2.6.3-rc2-1.bz2 and
> <URL:http://www.metaparadigm.com/~mclark/uml/uml-2.6.3-skas-1.patch>)
> is crashing reproducibly
I've given a look to the problem and I think that it has already been 
discussed and that fixes were posted and included in next UML patch (not yet 
released). I do not have pointers at hand but search for "Kernel panic: 
kernel BUG at kernel/exit.c:793!" to get probably something interesting.

Also, UML for now does not work well in SMP mode (and it does not actually 
parallelize the work): the spinlock messages at the beginning suggest you are 
using it.

If you have a SMP host, use for the host the SKAS patch found at: 

http://www.user-mode-linux.org/~blaisorblade

since it has a critical fix for SMP mode.
-- 
Paolo Giarrusso, aka Blaisorblade
Linux registered user n. 292729



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Re: [uml-devel] UML crashing-the known scheduler bug

[Thomas Schwinge]

On Thu, Mar 11, 2004 at 08:55:46PM +0100, BlaisorBlade wrote:
> I've given a look to the problem and I think that it has already been 
> discussed and that fixes were posted and included in next UML patch (not yet 
> released).

OK. Using linux-2.6.4 with uml-patch-2.6.4-1 solved this problem.
I should have waited just one day... :-)

> Also, UML for now does not work well in SMP mode (and it does not actually 
> parallelize the work): the spinlock messages at the beginning suggest you are 
> using it.

I'm not using SMP mode, but these messages also disappeared with 2.6.4.

> If you have a SMP host, use for the host the SKAS patch found at: 
> 
> http://www.user-mode-linux.org/~blaisorblade
> 
> since it has a critical fix for SMP mode.

Are there any other differences between your SKAS mode patch and
<URL:http://www.metaparadigm.com/~mclark/uml/uml-2.6.3-skas-1.patch>?


Regards,
 Thomas


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Re: [uml-devel] UML crashing-the known scheduler bug

[BlaisorBlade]

Alle 02:00, sabato 13 marzo 2004, Thomas Schwinge ha scritto:
> On Thu, Mar 11, 2004 at 08:55:46PM +0100, BlaisorBlade wrote:

> > If you have a SMP host, use for the host the SKAS patch found at:
> >
> > http://www.user-mode-linux.org/~blaisorblade
> >
> > since it has a critical fix for SMP mode.
>
> Are there any other differences between your SKAS mode patch and
> <URL:http://www.metaparadigm.com/~mclark/uml/uml-2.6.3-skas-1.patch>?

My code has only that change (that one is just a port of older version of the 
patch I provide); for that patch, however, you need to have already applied 
the UML patch, while I've built a clean patch for a vanilla *and*, in 
alternative, one that applies onto the Uml patch.

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



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