pg_dump strangeness

I'm having an issue with pg_dump crashing one of my servers. I was
running PG 7.2.1 now running 7.2.4 on RedHat 7.3 with up to date
patches. It happens when I'm dumping a largish (for me) database. The
database has two tables one with 1.2 million entries the other has 3.5
million entries, there are also about 700,000 blobs with signatures. The
exact command I'm using is.

pg_dump -Fc -b docarc >docarc.cust

It usually doesn't happen on the first iteration it's the second that
brings the box down. I ran it by hand on the console Saturday and it
slowly destabilized the system. I lost the title bars on the windows and
then the gnome task bar. Only the mouse cursor moved but it did not
responded to clicks or keyboard. I was able to restart the box from a
telnet session.

I added more memory to the box and that seems to be helping. It now
takes four runs to kill the box.

Any clue to the root of the problem? OS, hardware, postgresql, something
misconfigured???

Thanks,
Lane

From the system logfile -

Mar 10 02:34:08 internal kernel: Unable to handle kernel NULL pointer
dereference at virtual address 00000020

Mar 10 02:34:08 internal kernel: printing eip:

Mar 10 02:34:08 internal kernel: c013bbee

Mar 10 02:34:08 internal kernel: *pde = 00000000

Mar 10 02:34:08 internal kernel: Oops: 0000

Mar 10 02:34:08 internal kernel: sis sisfb agpgart 8139too mii usb-ohci
usbcore ext3 jbd dpt_i2o sd_mod scsi_mod

Mar 10 02:34:08 internal kernel: CPU: 0

Mar 10 02:34:08 internal kernel: EIP: 0010:[<c013bbee>] Not
tainted

Mar 10 02:34:08 internal kernel: EFLAGS: 00010286

Mar 10 02:34:08 internal kernel:

Mar 10 02:34:08 internal kernel: EIP is at block_read_full_page [kernel]
0xe (2.4.18-26.7.x)

Mar 10 02:34:08 internal kernel: eax: 00000000 ebx: e1025d34 ecx:
00000000 edx: 00000000

Mar 10 02:34:08 internal kernel: esi: c15d46f0 edi: c02d4a24 ebp:
c15d470c esp: e2261d90

Mar 10 02:34:08 internal kernel: ds: 0018 es: 0018 ss: 0018

Mar 10 02:34:08 internal kernel: Process pg_dump (pid: 13593,
stackpage=e2261000)

Mar 10 02:34:08 internal kernel: Stack: 00000001 ded15500 e1043540
c01cc410 dd36b600 c020dd17 e2260000 0000000c

Mar 10 02:34:08 internal kernel: e2261eb0 0000000c e1043540
00000282 c01cc431 dd36b600 00000000 00000000

Mar 10 02:34:08 internal kernel: c01cd39b 00000283 0000000c
e1025d34 c15d46f0 c02d4a24 00001417 c0128a23

Mar 10 02:34:08 internal kernel: Call Trace: [<c01cc410>] sock_wfree
[kernel] 0x0 (0xe2261d9c))

Mar 10 02:34:08 internal kernel: [<c020dd17>] unix_write_space [kernel]
0x37 (0xe2261da4))

Mar 10 02:34:08 internal kernel: [<c01cc431>] sock_wfree [kernel] 0x21
(0xe2261dc0))

Mar 10 02:34:08 internal kernel: [<c01cd39b>] kfree_skbmem [kernel] 0xb
(0xe2261dd0))

Mar 10 02:34:08 internal kernel: [<c0128a23>] __remove_inode_page
[kernel] 0x33(0xe2261dec))

Mar 10 02:34:08 internal kernel: [<e7946a20>] ext3_get_block [ext3] 0x0
(0xe2261df4))

Mar 10 02:34:08 internal kernel: [<c012fdac>] reclaim_page [kernel]
0x1ec (0xe2261dfc))

Mar 10 02:34:08 internal kernel: [<c0132171>] __alloc_pages_limit
[kernel] 0x71(0xe2261e1c))

Mar 10 02:34:08 internal kernel: [<c0132239>] __alloc_pages [kernel]
0x99 (0xe2261e30))

Mar 10 02:34:08 internal kernel: [<c0126cb0>] do_anonymous_page [kernel]
0x50 (0xe2261e64))

Mar 10 02:34:08 internal kernel: [<e7948e65>] ext3_mark_iloc_dirty
[ext3] 0x35 (0xe2261e68))

Mar 10 02:34:08 internal kernel: [<c0126da3>] do_no_page [kernel] 0x33
(0xe2261e88))

Mar 10 02:34:08 internal kernel: [<c01cb02c>] sys_recvfrom [kernel] 0xec
(0xe2261eac))

Mar 10 02:34:08 internal kernel: [<c0126fea>] handle_mm_fault [kernel]
0xca (0xe2261ec0))

Mar 10 02:34:08 internal kernel: [<c01324a0>] __get_free_pages [kernel]
0x10 (0xe2261ee0))

Mar 10 02:34:08 internal kernel: [<c0146b83>] __pollwait [kernel] 0x33
(0xe2261ee4))

Mar 10 02:34:08 internal kernel: [<c011456a>] do_page_fault [kernel]
0x12a (0xe2261f08))

Mar 10 02:34:08 internal kernel: [<c01286e9>] do_brk [kernel] 0x249
(0xe2261f44))

Mar 10 02:34:08 internal kernel: [<c01cb05d>] sys_recv [kernel] 0x1d
(0xe2261f6c))

Mar 10 02:34:08 internal kernel: [<c0127452>] sys_brk [kernel] 0xb2
(0xe2261f94))

Mar 10 02:34:08 internal kernel: [<c0114440>] do_page_fault [kernel] 0x0
(0xe2261fb0))

Mar 10 02:34:08 internal kernel: [<c0108a4c>] error_code [kernel] 0x34
(0xe2261fb8))