ubifs mount fails at ubifs_unpack_bits+0x120/0x1fc

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Here's the attach followed by a mount request that fails with
 ubifs_unpack_bits+0x120/0x1fc.

Any ideas?

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UBI: attaching mtd12 to ubi0
UBI: physical eraseblock size:   131072 bytes (128 KiB)
UBI: logical eraseblock size:    126976 bytes
UBI: smallest flash I/O unit:    2048
UBI: sub-page size:              512
UBI: VID header offset:          2048 (aligned 2048)
UBI: data offset:                4096
UBI: attached mtd12 to ubi0
UBI: MTD device name:            "nand_part2"
UBI: MTD device size:            512 MiB
UBI: number of good PEBs:        4095
UBI: number of bad PEBs:         1
UBI: max. allowed volumes:       128
UBI: wear-leveling threshold:    4096
UBI: number of internal volumes: 1
UBI: number of user volumes:     2
UBI: available PEBs:             0
UBI: total number of reserved PEBs: 4095
UBI: number of PEBs reserved for bad PEB handling: 40
UBI: max/mean erase counter: 8/4
UBI: background thread "ubi_bgt0d" started, PID 2077
UBI device number 0, total 4095 LEBs (519966720 bytes, 495.9 MiB), available 0 L
EBs (0 bytes), LEB size 126976 bytes (124.0 KiB)
UBIFS: background thread "ubifs_bgt0_1" started, PID 2082
UBIFS: recovery needed
Unable to handle kernel paging request at virtual address c88d9003
pgd = c5ca4000
[c88d9003] *pgd=a7c18011, *pte=00000000, *ppte=00000000
Internal error: Oops: 7 [#1]
Modules linked in:
CPU: 0
PC is at ubifs_unpack_bits+0x120/0x1fc
LR is at is_a_node+0x3c/0xf0
pc : [<c0c697c8>]    lr : [<c0c73acc>]    Not tainted
sp : c5c91b18  ip : c5c91b40  fp : c5c91b3c
r10: c5c91b44  r9 : 0000000c  r8 : 0000001c
r7 : c5c91b40  r6 : 00000000  r5 : c88d9002  r4 : 00000004
r3 : 00000000  r2 : 00000004  r1 : c5c91b40  r0 : c5c91b44
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  Segment user
Control: 5317F
Table: A5CA4000  DAC: 00000015
Process mount (pid: 2081, stack limit = 0xc5c90250)
Stack: (0xc5c91b18 to 0xc5c92000)
1b00:                                                       c5c1c000 c5c1c000 
1b20: c88d9000 c88d9002 00000000 00000000 c5c91b68 c5c91b40 c0c73acc c0c696b8 
1b40: 00000000 c88d9002 c60ff620 c5c1c000 0001eee4 c5c90000 0000000c c5c91bb8 
1b60: c5c91b6c c0c73d04 c0c73aa0 0001f000 00000000 00000000 c88d9000 0001a26b 
1b80: 000003c8 00000000 00000000 00000100 c5c91c24 c5c1c000 c5c1c000 00000000 
1ba0: 00000004 c5c1c3c4 00000120 c5c91bec c5c91bbc c0c75788 c0c73b90 00000120 
1bc0: 00000000 c5c91c24 c65124e4 c5c1c000 00000000 00000004 c5c1c000 00000120 
1be0: c5c91c64 c5c91bf0 c0c5fb9c c0c7571c c60ff83c c0d28a54 00000000 00000000 
1c00: 80000001 c5c1c000 c5b6c2f0 00fa3df8 00000000 c5c91c58 c5c91c24 c0c6efd8 
1c20: c0c6e018 00000000 00000000 c657a780 000006ba 00013ee0 00000058 00000007 
1c40: c5c90000 c5c1c09c c5c1c000 c5c1c000 c6512400 00000000 c5c91c80 c5c91c68 
1c60: c0c603a8 c0c5fa74 c5c1c338 c0f22240 000000ad c5c91ccc c5c91c84 c0c73284 
1c80: c0c6029c 00000000 00000020 00000000 00000000 000009dd 00000000 c891c00b 
1ca0: 00000000 c5c1c338 c5c1c338 00000000 00000000 0001f000 00000001 00000000 
1cc0: c5c91d50 c5c91cd0 c0c4f21c c0c72bf4 c5c91d0c c5c91ce0 c5c1c8bc c5c91cfc 
1ce0: 00000020 00000005 c0e43ad8 c6512724 c6512724 00000005 c0ca7188 00000000 
1d00: c5c90020 c6512600 c5c90000 c5cea000 c6512600 c66b1be0 c5c1c37c c5c1c4c4 
1d20: c5c1c374 00000000 00000000 c6512600 c66b1be0 c6512600 00008000 c5cea000 
1d40: c0e98bac c5c91dbc c5c91d54 c0c5114c c0c4e6bc c0beb244 00000000 00000001 
1d60: 00000f2d 1d673000 00000000 c5c89000 00000003 00000000 00000000 00000001 
1d80: 0001f000 00000004 c66aa5dc 0f800002 c5c89006 c7c0caa0 fffffff4 c5c89000 
1da0: c5cea000 c0e98bac c5cea000 c5c86000 c5c91de4 c5c91dc0 c0bd5044 c0c50e74 
1dc0: c7c0caa0 c0e98bac ffffffed c5cea000 c5c89000 00008000 c5c91e00 c5c91de8 
1de0: c0bd592c c0bd4ffc 00000000 00000000 00000000 c5c91f74 c5c91e04 c0bec880 
1e00: c0bd5904 00000002 c65fc394 c5c91e28 c5c91e1c c0ba4fc8 c0ca69f0 c5c91e60 
1e20: c5c91e2c c0b7592c c0ba4fc8 00000000 c5c91f4c 00000017 ffffffff c0e8e788 
1e40: 00000017 c5c91f0c 00076000 20000013 40169000 c5c91f08 c5c91e64 c0b75ab0 
1e60: c0b75724 c64d18a0 c5c91ecc c5c91ecc c6071000 c5c91ea8 c5c91e84 c0bddc8c 
1e80: c0bdd694 c5c91e90 c6071000 00000001 fffffffe 00000001 c5c91ecc c5c90000 
1ea0: 20000013 c5c90000 c5c91f00 c5c91eb8 c0bb52e4 c0bb4c30 00000044 00000044 
1ec0: 000200d0 00000001 00000000 00000001 c0e948bc c0e948bc 00000000 00075018 
1ee0: 000000d0 c0e948bc ffffffff c5c91f40 00000018 c6b07a14 c7c0c7a0 c5c91f74 
1f00: c5c91f0c c0b6f980 00000001 00000001 00000000 00000000 00076000 00001000 
1f20: 00075018 00000018 c5cea000 c5c91f84 c5c90000 40169000 c5c91f74 00000000 
1f40: c5c91f54 00000000 c0beb080 00000000 c6071000 bec92e6f 00008000 c0b6ff84 
1f60: c5c90000 40169000 c5c91fa4 c5c91f78 c0bec978 c0bec2c0 c5cea000 c5c89000 
1f80: c5c86000 c5cea000 00075018 bec92ca0 4001d660 00000015 00000000 c5c91fa8 
1fa0: c0b6fde0 c0bec8f8 00075018 bec92ca0 bec92e6f bec92e76 bec92e69 00008000 
1fc0: 00075018 bec92ca0 4001d660 00075018 00008000 00000000 40169000 00000000 
1fe0: 40111e60 bec92bec 00034968 40111e6c 60000010 bec92e6f 00000000 00000000 
Backtrace: 
[<c0c696a8>] (ubifs_unpack_bits+0x0/0x1fc) from [<c0c73acc>] (is_a_node+0x3c/0xf
0)
[<c0c73a90>] (is_a_node+0x0/0xf0) from [<c0c73d04>] (dbg_check_ltab+0x184/0x644)
 r8 = 0000000C  r7 = C5C90000  r6 = 0001EEE4  r5 = C5C1C000
 r4 = C60FF620 
[<c0c73b80>] (dbg_check_ltab+0x0/0x644) from [<c0c75788>] (ubifs_lpt_start_commi
t+0x7c/0xabc)
[<c0c7570c>] (ubifs_lpt_start_commit+0x0/0xabc) from [<c0c5fb9c>] (do_commit+0x1
38/0x828)
[<c0c5fa64>] (do_commit+0x0/0x828) from [<c0c603a8>] (ubifs_run_commit+0x11c/0x1
58)
[<c0c6028c>] (ubifs_run_commit+0x0/0x158) from [<c0c73284>] (ubifs_rcvry_gc_comm
it+0x6a0/0x740)
 r6 = 000000AD  r5 = C0F22240  r4 = C5C1C338 
[<c0c72be4>] (ubifs_rcvry_gc_commit+0x0/0x740) from [<c0c4f21c>] (ubifs_fill_sup
er+0xb70/0x18a0)
[<c0c4e6ac>] (ubifs_fill_super+0x0/0x18a0) from [<c0c5114c>] (ubifs_get_sb+0x2e8
/0x364)
[<c0c50e64>] (ubifs_get_sb+0x0/0x364) from [<c0bd5044>] (vfs_kern_mount+0x58/0x9
0)
[<c0bd4fec>] (vfs_kern_mount+0x0/0x90) from [<c0bd592c>] (do_kern_mount+0x38/0x4
c)
 r8 = 00008000  r7 = C5C89000  r6 = C5CEA000  r5 = FFFFFFED
 r4 = C0E98BAC 
[<c0bd58f4>] (do_kern_mount+0x0/0x4c) from [<c0bec880>] (do_mount+0x5d0/0x638)
 r6 = 00000000  r5 = 00000000  r4 = 00000000 
[<c0bec2b0>] (do_mount+0x0/0x638) from [<c0bec978>] (sys_mount+0x90/0xdc)
[<c0bec8e8>] (sys_mount+0x0/0xdc) from [<c0b6fde0>] (ret_fast_syscall+0x0/0x2c)
 r7 = 00000015  r6 = 4001D660  r5 = BEC92CA0  r4 = 00075018
Code: e3130004 1a000000 ebfc28ad e3560000 (e5d5e001) 
 Segmentation fault