I understand there is a bug in earlier revisions of Schizo PCI bridge
(that I have in my V480) and we do not have a workaround for that. Now
when I happen to hit it, I get a crash in the handler and that seems a
bug whether or not we have the workaround.
In particular, it seems that pbm->pci_bus->self is NULL and that causes
a NULL pointer dereference in schizo_pcierr_intr_other:
pci_read_config_word(pbm->pci_bus->self, PCI_STATUS, &stat);
Since the error happens during PCI scanning, maybe we just do not have
this field initialized yet - in pci_scan_one_pbm() or in something it
calls?
This dmesg excerpt from annotated source, mostly for background.
[ 61.300577] PCI: Scanning PBM /pci@9,600000
[ 61.304867] schizo f009b070: PCI host bridge to bus 0003:00
[ 61.310385] pci_bus 0003:00: root bus resource [io 0x7ffe9000000-0x7ffe9ffffff] (bus address [0x0000-0xffffff])
[ 61.320515] pci_bus 0003:00: root bus resource [mem 0x7fb00000000-0x7fbffffffff] (bus address [0x00000000-0xffffffff])
[ 61.331173] pci_bus 0003:00: root bus resource [bus 00]
[ 61.337539] schizo_pcierr_intr, pbm=fff000b0fdb34000
[ 61.342444] schizo_pcierr_intr, afar=4194496
[ 61.346690] schizo_pcierr_intr, afsr=13421772800
[ 61.351280] schizo_pcierr_intr, calling schizo_pcierr_intr_other
[ 61.357259] schizo_pcierr_intr_other: start
[ 61.361421] schizo_pcierr_intr_other, csr=1688858467696703
[ 61.366879] schizo_pcierr_intr_other, pbm=fff000b0fdb34000
[ 61.372339] schizo_pcierr_intr_other, pbm->pci_bus=fff000b0fdb34800
[ 61.378580] schizo_pcierr_intr_other, pbm->pci_bus->self= (null)
[ 61.385344] Unable to handle kernel NULL pointer dereference
[ 61.390970] tsk->{mm,active_mm}->context = 0000000000000000
[ 61.396515] tsk->{mm,active_mm}->pgd = fff000b000002000
[ 61.401716] \|/ ____ \|/
[ 61.401716] "@'/ .. \`@"
[ 61.401716] /_| \__/ |_\
[ 61.401716] \__U_/
[ 61.416362] swapper/0(0): Oops [#1]
[ 61.419837] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 3.18.0-rc1-00422-g2cc9188-dirty #24
[ 61.427975] task: fff000b0fd8e9c40 ti: fff000b0fd928000 task.ti: fff000b0fd928000
[ 61.435426] TSTATE: 0000004480e01602 TPC: 00000000004455e4 TNPC: 00000000004455e8 Y: 00000000 Not tainted
[ 61.445230] TPC: <schizo_pcierr_intr+0x104/0x560>
[ 61.449897] g0: 0000000000000000 g1: 0000000000000000 g2: 0000000000a10f78 g3: 000000000000000a
[ 61.458563] g4: fff000b0fd8e9c40 g5: fff000b0fdd82000 g6: fff000b0fd928000 g7: 000000000000000a
[ 61.467229] o0: 000000000000003d o1: 0000000000000000 o2: 0000000000000006 o3: fff000b0ffa5fc7e
[ 61.475894] o4: 0000000000060000 o5: c000000000000000 sp: fff000b0ffa5f3c1 ret_pc: 00000000004455cc
[ 61.484909] RPC: <schizo_pcierr_intr+0xec/0x560>
[ 61.489500] l0: fff000b0fd8e9c40 l1: 0000000000a20800 l2: 0000000000000000 l3: 000000000119a430
[ 61.498164] l4: 0000000001742400 l5: 00000000011cfbe0 l6: 00000000011319c0 l7: fff000b0fd8ea348
[ 61.506830] i0: 0000000000000000 i1: fff000b0fdb34000 i2: 0000000320000000 i3: 0000000000000000
[ 61.515497] i4: 00060002010b003f i5: 0000040004e02000 i6: fff000b0ffa5f481 i7: 00000000004a9920
[ 61.524175] I7: <handle_irq_event_percpu+0x40/0x140>
[ 61.529099] Call Trace:
[ 61.531531] [00000000004a9920] handle_irq_event_percpu+0x40/0x140
[ 61.537681] [00000000004a9a58] handle_irq_event+0x38/0x80
[ 61.543145] [00000000004ac77c] handle_fasteoi_irq+0xbc/0x200
[ 61.548860] [00000000004a9084] generic_handle_irq+0x24/0x40
[ 61.554500] [000000000042be0c] handler_irq+0xac/0x100
--
Meelis Roos (mroos@xxxxxxxx)
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