[ppc64] 2.6.29-git7 : offlining a cpu causes an exception

[Sachin Sant]

While executing CPU HotPlug[1] tests i observed that during
every cpu offline process an exception is thrown.

cpu 0x2: Vector: 700 (Program Check) at [c0000000074c7ca0]
    pc: 00000000007b6640
    lr: 000000000079ddc0
    sp: c0000000074c7f20
   msr: 8000000000081002
  current = 0xc0000000fe1c8580
  paca    = 0xc000000000ab2800
    pid   = 0, comm = swapper
2:mon> r
R00 = 0000000000000000   R16 = 0000000000000002
R01 = c0000000074c7f20   R17 = 0000000000000000
R02 = 00000000009e8dc0   R18 = 0000000000000000
R03 = 0000000000008278   R19 = 0000000000000000
R04 = 0000000000008000   R20 = 0000000000000000
R05 = 0000000000000002   R21 = 0000000000000000
R06 = 0000000000000002   R22 = c000000000b33ae0
R07 = 0000000000000000   R23 = 0000000000000000
R08 = 0000000000000000   R24 = 0000000000000002
R09 = 00000000000082fc   R25 = 0000000000000000
R10 = 0000000000000000   R26 = 0000000000000004
R11 = a000000000001002   R27 = c000000000a95bd8
R12 = a000000000000000   R28 = 0000000000000008
R13 = c000000000ab2800   R29 = ffffffffffffffff
R14 = 0000000000000000   R30 = c00000000095e750
R15 = 0000000007531868   R31 = 0000000007d70b20
pc  = 00000000007b6640
lr  = 000000000079ddc0
msr = 8000000000081002   cr  = 22000004
ctr = 0000000000000000   xer = 0000000000000020   trap =  700
2:mon> u
SLB contents of cpu 2
00 c000000008000000 40004f7ca3000500  1T  ESID=   c00000  VSID=       4f7ca3 LLP:100
01 d000000008000000 4000eb71b0000510  1T  ESID=   d00000  VSID=       eb71b0 LLP:110
24 0000000008000000 0000000000000c80 256M ESID=        0  VSID=            0 LLP:  0
2:mon>

I can recreate this problem very easily on power5
as well as power6 box.

2.6.29-git6 did not have this problem. Let me know if there
is any other information i can provide. I have attached the
dmesg log here.

Thanks
-Sachin

[1] -> CPU Hotplug test which is part of LTP.

-- 

---------------------------------
Sachin Sant
IBM Linux Technology Center
India Systems and Technology Labs
Bangalore, India
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