[Verizon Samsung Galaxy S III] Bort76:
Yep, probably hardware

I'm inclined to agree. This started out as memory read/write (journaling?) errors, which made me believe it was corrupted storage, but that hasn't been repeatable. The issue seems really unpredictable and occurs at random times. The last few times, rather than freezing, it has mainly rebooted -- if it's even the same issue. Anyway, here is my latest last_kmsg (and the last one that I'm going to bore anyone with) in case it makes any lightbulbs go off for anyone.

I'm just showing the error onwards.

[79406.365499] Internal error: Oops - undefined instruction: 0 [#1] PREEMPT SMP ARM
[79406.372061] CPU: 1 Tainted: G W (3.4.104-dkp-g0e88163-24802-ga15dfe2 #1)
[79406.379935] PC is at 0xe08955de
[79406.383018] LR is at msm_pm_spm_power_collapse+0x798/0x9c0
[79406.388450] pc : [<e08955de>] lr : [<c0b35d40>] psr: 60000093
[79406.388481] sp : ef147f10 ip : ef146000 fp : 0040007f
[79406.399926] r10: c0aa6324 r9 : 00000000 r8 : 00000002
[79406.405206] r7 : 00000000 r6 : fffffffc r5 : 00000001 r4 : c0f1b648
[79406.411646] r3 : 00000001 r2 : 00000002 r1 : ef146010 r0 : 00000000
[79406.418238] Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment kernel
[79406.425594] Control: 10c5787d Table: 9770c06a DAC: 00000015
[79406.431240]
[79406.431240] PC: 0xe089555e:
[79406.435513] 555c db044000 616f409b 87d00c35 6ea82b1a 0785112c 1439b8c0 399c048f d55afd9c
[79406.443662] 557c 68d9192d cf6d495f d2d8b3ff a46e6782 cef92332 fd929e34 c6d85492 47842449
[79406.451811] 559c 9f65b694 337fefe6 b2b89c24 81e52171 b58f27c2 2e9b18c5 bf68be28 01506ae9
[79406.459990] 55bc 9abc4d4a 1df4de8c 1ece550a 8d3d63a5 779c57c1 6bd45231 8afaa8aa a91b95fb
[79406.468139] 55dc 94ff6726 6f346475 9dff33d1 e67647fa 9aa2cbc6 9d2d450a 57a7efc6 2ab066f1
[79406.476288] 55fc c4e355c0 706c1aa4 8884a251 52fbff39 0b00b5c0 4c55f5fc 74a16b0c f48ca9a5
[79406.484467] 561c 6b41780d 4c88bbf6 d3d88330 80945b49 31003005 ef8ae392 0810da77 4a530350
[79406.492616] 563c 6dd87d1b 82151b2a 8b97cbcd d8382c4e 3f491579 c73a64e5 0b9f73e7 3a973b42
[79406.500765] 565c c457695f 29978d72 e9f377fb 3fb00a15 368e194d d71bce75 e5aec24e cf7d2ada
[79406.508945]
[79406.508945] LR: 0xc0b35cc0:
[79406.513187] 5cc0 e30b0644 e30b4648 e34c00f1 e34c40f1 eb01968a e5943000 e3530000 13e06000
[79406.521336] 5ce0 13a08002 13a07000 1a000009 ea000010 e2566001 e1a03009 13a0c001 03a0c000
[79406.529515] 5d00 e3590000 03a0c000 120cc001 e35c0000 0a000007 e593a000 e1a00003 e1a01008
[79406.537695] 5d20 e1a02007 e5939004 e12fff3a e3100902 0affffee e30b0644 e34c00f1 eb0196aa
[79406.545813] 5d40 eaffff71 ebfaa87e eafffe24 e1a0600d e3c6cd7f e3cc903f e599a004 e35a0000
[79406.553993] 5d60 0a000063 ee11ef50 e38e160f ee011f50 f57ff06f eef82a10 e3c23101 eee83a10
[79406.562142] 5d80 e1a0600d e30f9780 e3c6cd7f e34c90e9 e3cca03f e59a1014 e3510001 e0896301
[79406.570291] 5da0 8a000057 ebffd283 e321f0d2 e286e000 e1a0d00e e321f0d7 e286e00c e1a0d00e
[79406.578470]
[79406.578470] SP: 0xef147e90:
[79406.582804] 7e90 7fffffff 00000005 00000000 c0dbc348 00000000 00000002 c0e9f9f0 e08955e2
[79406.590892] 7eb0 60000093 c0b297d4 00000000 64100000 c0b2952c c0b2952c 00000000 ef146010
[79406.599041] 7ed0 00000002 00000001 c0f1b648 00000001 fffffffc 00000000 00000002 00000000
[79406.607190] 7ef0 c0aa6324 0040007f ef146000 ef147f10 c0b35d40 e08955de 60000093 ffffffff
[79406.615369] 7f10 00000002 c30767c0 3f46ae8d 00004838 00000000 ef146030 ef146000 c0b053a8
[79406.623518] 7f30 000024d6 00000000 00001720 00000000 00000254 c0ebcb48 00000000 00000002
[79406.631667] 7f50 c0ebcb64 00000000 3f46ae8d 00004838 00000254 c30767c0 77359400 000007e2
[79406.639847] 7f70 00000000 00000000 c0f04ccc c0e9f640 c0dbca18 c30767c0 c0dbe0a4 ef146000
[79406.647995]
[79406.647995] IP: 0xef145f80:
[79406.652238] 5f80 00000000 32823282 ef121000 00000001 ef1210c4 ef144000 00000000 ef121000
[79406.660417] 5fa0 0420804c c0a47788 ef120ff8 ef121128 00000001 ef121170 ef145fb8 ef145fb8
[79406.668566] 5fc0 ef121170 ef145fc0 00000000 ef121000 00000000 c0a6cb14 00000001 00000001
[79406.676715] 5fe0 00000000 00020002 ef145fe8 ef145fe8 00000013 c0009364 c0c0c0c0 c0c0c0c0
[79406.684895] 6000 00000002 00000003 00000000 ef1213c0 c0e2ff50 00000001 00000015 ef1213c0
[79406.693044] 6020 ecac3a80 00865328 00000001 ecac3ab0 c0dbe940 c3076940 d7701780 ef147ed0
[79406.701192] 6040 c0b99880 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.709372] 6060 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.717521]
[79406.717551] R1: 0xef145f90:
[79406.721763] 5f90 ef1210c4 ef144000 00000000 ef121000 0420804c c0a47788 ef120ff8 ef121128
[79406.729943] 5fb0 00000001 ef121170 ef145fb8 ef145fb8 ef121170 ef145fc0 00000000 ef121000
[79406.738092] 5fd0 00000000 c0a6cb14 00000001 00000001 00000000 00020002 ef145fe8 ef145fe8
[79406.746241] 5ff0 00000013 c0009364 c0c0c0c0 c0c0c0c0 00000002 00000003 00000000 ef1213c0
[79406.754420] 6010 c0e2ff50 00000001 00000015 ef1213c0 ecac3a80 00865328 00000001 ecac3ab0
[79406.762599] 6030 c0dbe940 c3076940 d7701780 ef147ed0 c0b99880 00000000 00000000 00000000
[79406.770748] 6050 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.778897] 6070 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.787046]
[79406.787046] R4: 0xc0f1b5c8:
[79406.791319] b5c8 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.799468] b5e8 00000000 00000000 00000000 ef11e800 00000000 00000003 00000000 00000000
[79406.807648] b608 00000000 00000000 00000000 00030003 c0f1b618 c0f1b618 00000000 00000000
[79406.815796] b628 00000000 00000000 00000000 0000000f 0000000f 0000000f 00000000 00000000
[79406.823945] b648 c0df8f90 00000000 c0dbf29c 00000001 00000000 c0f1b65c c0f1b65c 00000000
[79406.832094] b668 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[79406.840274] b688 c0e9f344 00000000 c0e9f350 00000000 c0e9f35c 00000000 c0e9f368 00000000
[79406.848423] b6a8 c0e9f374 00000000 00000000 00000000 c0e9f380 ef11fb48 ef2e1ed8 00000001
[79406.856602]
[79406.856602] R10: 0xc0aa62a4:
[79406.860936] 62a4 e3c1203f e3a09008 e592600c e08d1009 e1a0300e e58d9008 e24cb004 e1a00009
[79406.869085] 62c4 e586e224 e592800c e58db014 e5887220 e592200c ebfecc33 eaffff78 eb03d09c
[79406.877234] 62e4 eaffff7f e1a0300d e3c30d7f e3c0103f e5912004 e3520000 0a000004 ee113f50
[79406.885413] 6304 e383060f ee010f50 f57ff06f e12fff1e e10fc000 e31c0080 1afffff7 e7f001f2
[79406.893562] 6324 e3510000 e16d41f0 e58d6008 e58de00c 0a000013 e3510002 8a00000c e1a0300d
[79406.901711] 6344 e3c30d7f e3c0103f e5912004 e3520000 0a000017 ee115f50 e385660f ee016f50
[79406.909891] 6364 f57ff06f eef8ca10 e3cc3101 eee83a10 e1cd40d0 e3a00001 e59d6008 e28dd00c
[79406.918040] 6384 e49df004 eef85a10 e1a0000d e3150101 e3c01d7f e3c1403f 1a000009 e5946014
[79406.926219] Process swapper/1 (pid: 0, stack limit = 0xef1462f0)
[79406.932293] Stack: (0xef147f10 to 0xef148000)
[79406.936535] 7f00: 00000002 c30767c0 3f46ae8d 00004838
[79406.944776] 7f20: 00000000 ef146030 ef146000 c0b053a8 000024d6 00000000 00001720 00000000
[79406.952863] 7f40: 00000254 c0ebcb48 00000000 00000002 c0ebcb64 00000000 3f46ae8d 00004838
[79406.961104] 7f60: 00000254 c30767c0 77359400 000007e2 00000000 00000000 c0f04ccc c0e9f640
[79406.969253] 7f80: c0dbca18 c30767c0 c0dbe0a4 ef146000 00000000 c0302e58 00000000 c0ab0514
[79406.977432] 7fa0: 00000000 00000002 00000001 ef146038 00551353 00000000 00000000 c0dbcdf8
[79406.985490] 7fc0: c0dbe940 c0dbcba0 c0dbcba0 c0dbcdf8 c0dbe0a4 c0dbe940 3f17a54f 00004838
[79406.993730] 7fe0: c0b5afd0 c0e9ff18 00000000 c0b5a8e4 c0e9f84c 80d561f4 c0c0c0c0 c0c0c0c0
[79407.001910] [<c0b35d40>] (msm_pm_spm_power_collapse+0x798/0x9c0) from [<c0b053a8>] (msm_cpuidle_enter+0x608/0xe7c)
[79407.012226] [<c0b053a8>] (msm_cpuidle_enter+0x608/0xe7c) from [<c0ab0514>] (cpu_idle+0x678/0x928)
[79407.021107] [<c0ab0514>] (cpu_idle+0x678/0x928) from [<c0b5a8e4>] (secondary_start_kernel+0x218/0x290)
[79407.030294] [<c0b5a8e4>] (secondary_start_kernel+0x218/0x290) from [<80d561f4>] (0x80d561f4)
[79407.038778] Code: 5231779c a8aa6bd4 95fb8afa 6726a91b (647594ff)
[79407.044943] ---[ end trace 5646cb3affc89c42 ]---
[79407.049399] Kernel panic - not syncing: Fatal exception
[79407.054679] CPU0: stopping
[79407.057274] [<c0aba350>] (unwind_backtrace+0x0/0x2f8) from [<c0ab8a70>] (handle_IPI+0x618/0x680)
[79407.066064] [<c0ab8a70>] (handle_IPI+0x618/0x680) from [<c0008894>] (gic_handle_irq+0x228/0x31c)
[79407.074792] [<c0008894>] (gic_handle_irq+0x228/0x31c) from [<c0b2965c>] (__irq_usr+0x3c/0x60)
[79407.083338] Exception stack(0xd7429fb0 to 0xd7429ff8)
[79407.088374] 9fa0: 00000003 00000000 7e000001 0000003b
[79407.096492] 9fc0: 786b4be8 722702cc 786b3c14 00c00641 786b3c10 7ac6255c 786b3c14 00000010
[79407.104702] 9fe0: fffffffc 7ac624e8 727f37a5 727f39aa 800f0030 ffffffff
[79407.211493] Rebooting in 5 seconds..
[79412.215217] Going down for restart now
[79412.218208] msm_restart : clear reset flag

I'll try a few more things like earlier/later rom versions and a long-overdue full wipe of everything. Mostly, this has been an excuse to start looking for a reasonably priced S5. Unless I stumble on a solution, which doesn't seem likely, I don't plan to keep monopolizing this thread. Thanks for everyone's help!