I have a vmcore generated on RHEL6.1 that newer versions of crash have trouble analyzing (5.1.1-2.el6 seems to work ok).

I can provide additional binary files if needed, just let me know what convention best suits the list (ftp, private email attachment, etc.)

Crash Version:        OS:               Result:

crash 5.1.8           Debian wheezy     faults

crash 5.1.7-1.el6     RHEL6.2 Alpha     faults

crash 5.1.1-2.el6     RHEL6.1           ok

Kernel:

2.6.32-131.0.15.el6.exp10.bz16586.x86_64    (2.6.32-131.0.15 + a fix for Red Hat bz-707268)

Interesting warnings when starting crash:

WARNING: sparsemem: invalid section number: 137438888923

WARNING: sparsemem: invalid section number: 137438888923

First fault, null pointer deference:

please wait... (determining panic task)        

Program received signal SIGSEGV, Segmentation fault.

x86_64_get_dumpfile_stack_frame (rsp=0x7fffffffcc58, rip=0x7fffffffcc50,

    bt_in=0x7fffffffcce0) at x86_64.c:4183

4183                    ur_rip = ULONG(user_regs +

(gdb) p user_regs

$1 = 0x0

Workaround, check that bt->machdep is not NULL:

diff -Nupr crash-5.1.8/x86_64.c crash-5.1.8.new/x86_64.c

--- crash-5.1.8/x86_64.c        2011-09-16 15:01:12.000000000 -0400

+++ crash-5.1.8.new/x86_64.c    2011-09-28 14:12:45.347188571 -0400

@@ -4178,7 +4178,7 @@ x86_64_get_dumpfile_stack_frame(struct b

                                goto skip_stage;

                        }

                }

-       } else if (ELF_NOTES_VALID()) {

+       } else if (ELF_NOTES_VALID() && bt->machdep) {

                user_regs = bt->machdep;

                ur_rip = ULONG(user_regs +

                        OFFSET(user_regs_struct_rip));

Second fault, a curiously large n_descsz in elf note header:

please wait... (determining panic task)        

Program received signal SIGSEGV, Segmentation fault.

get_regs_from_note (note=0xd26472 "\b", ip=0x7fffffffc4e0, sp=0x7fffffffc4e8)

    at netdump.c:2221

2221            *sp = ULONG(user_regs + offset_sp);

(gdb) p *(Elf64_Nhdr *)note

$1 = {n_namesz = 8, n_descsz = 3438804992, n_type = 8}

Workaround, do not attempt reading registers from elf notes (this chunk of code was not present in crash 5.1.1):

diff -Nupr crash-5.1.8/netdump.c crash-5.1.8.new/netdump.c

--- crash-5.1.8/netdump.c       2011-09-16 15:01:12.000000000 -0400

+++ crash-5.1.8.new/netdump.c   2011-09-28 14:14:43.687183734 -0400

@@ -2286,7 +2286,7 @@ get_netdump_regs_x86_64(struct bt_info *

                bt->machdep = (void *)user_regs;

        }

-

+#if 0

        if (ELF_NOTES_VALID() &&

            (bt->flags & BT_DUMPFILE_SEARCH) && DISKDUMP_DUMPFILE() &&

            (note = (Elf64_Nhdr *)

@@ -2305,7 +2305,7 @@ get_netdump_regs_x86_64(struct bt_info *

                bt->machdep = (void *)user_regs;

        }

-

+#endif

         machdep->get_stack_frame(bt, ripp, rspp);  }

Given the warning messages at the beginning of the process, I'm sure if I'm dealing with a corrupted or incomplete vmcore image.  Let me know what additional info could be useful if this seems worth debugging further.

Thanks,

-- Joe Lawrence