[Devel] ckpt-16-dev BUG() - bisected

[Nathan Lynch]

Pulled latest updates today, started seeing the bug below when doing
simple bash shell checkpoint/restart.  Git bisect blames:

commit 505d9949cac385c5111bbd8ff3d2e123d5c468d8
Author: Oren Laadan <orenl at cs.columbia.edu>
Date:   Sun May 31 12:59:40 2009 -0400

    c/r: [X86_32] validate task's cpu registers and tls during restart
    
    Check the eflags, segment registers and tls entries from the
    checkpoint image to prevent breakpoints inside the kernel code.
    
    Fixes in restore_thread() and load_cpu_regs():
            /* TODO: ADD SANITY CHECKS TO VERIFY VALIDITY OF VALUES */
    
    Based on patch from Alexey Dobriyan:
    https://lists.linux-foundation.org/pipermail/containers/2009-May/017886.html
        Segment registers are abstracted to allow i386 => x86_64
        migration (BTW, I'm not so sure if just making 32-bit selectors
        the same will achieve same effect)


kernel BUG at arch/x86/mm/checkpoint.c:86!
invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
last sysfs file: /sys/block/sda/size
Modules linked in:

Pid: 2236, comm: ckpt Not tainted (2.6.30-rc7-00054-g505d994 #55) 
EIP: 0060:[<c021c3dd>] EFLAGS: 00010202 CPU: 0
EIP is at encode_segment+0x51/0x57
EAX: 1fffe009 EBX: df03a720 ECX: 00000130 EDX: 1fffe00f
ESI: df996fb4 EDI: def3f250 EBP: de8abf18 ESP: de8abf18
 DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process ckpt (pid: 2236, ti=de8ab000 task=de8e28e0 task.ti=de8ab000)
Stack:
 de8abf38 c021cc07 decf51c0 def3f250 00000062 dc99a440 00000000 def3f250
 de8abf58 c038eb3c decf51c0 decf54e8 00000007 00000000 00000000 def3f250
 de8abf98 c038d7bf c07a69e0 00000001 00000001 00000000 def73ee0 c07ad224
Call Trace:
 [<c021cc07>] ? checkpoint_cpu+0x11a/0x426
 [<c038eb3c>] ? checkpoint_task+0x226/0x239
 [<c038d7bf>] ? do_checkpoint+0x404/0x511
 [<c038c669>] ? sys_checkpoint+0x6d/0x83
 [<c0202ce5>] ? syscall_call+0x7/0xb
Code: 74 2d 83 fa 7b b8 02 00 00 00 74 23 f6 c2 04 74 0a 89 d0 c1 e8 03 80 cc 80 eb 14 c1 ea 03 8d 42 fa 83 f8 02 77 05 80 cc 40 eb 04 <0f> 0b eb fe 5d c3 55 89 e5 e8 f9 72 fe ff 85 c0 74 40 83 f8 01 
EIP: [<c021c3dd>] encode_segment+0x51/0x57 SS:ESP 0068:de8abf18
---[ end trace 270dba57a69e79e1 ]---
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