----- Original Message -----
> > But I'm not sure what happens when an arm64 IRQ exception occurs when
> > the task is running in user space. Does it lay an exception frame down on the
> > process stack and then make the transition? (and therefore the user-space frame
> > above is legitimate?) Or does the user-space frame get laid down directly on the
> > IRQ stack? Unfortunately I don't know enough about arm64 exception
> > handling.
>
> Since I reviewed this IRQ stack patch in LAK-ML, I will be able to help you.
> but I don't have enough time to explain in details this week.
That's good news, your help will be greatly appreciated.
> > In any case, the bt should display "-- <IRQ stack> ...", and then dump
> > the user-to-kernel-space exception frame, wherever it lies, i.e., either on the
> > normal process stack or (maybe?) on the IRQ stack.
> >
> > Anyway, can you make the vmlinux/vmcore pair available for me to download?
> > You can send the details to me offline.
>
> I sent you a message which contains the link to those binaries.
Got them -- thanks!
Also, I was finally able to generate a vmcore on a RHEL7 4.5.0-based kernel,
where the crash occurred on cpu 1, and other 7 cpus were running in user space.
I do see the same problem w/respect to the IRQ-stack-to-user-space transition.
However, I do not have the "phantom" exception frame dumps on the IRQ
stacks that your dumpfile displays on the 7 non-crashing cpus, regardless
whether they came from kernel or user space.
Here is the output:
crash> sys
KERNEL: ../vmlinux
DUMPFILE: ../vmcore [PARTIAL DUMP]
CPUS: 8 [OFFLINE: 7]
DATE: Thu Jun 2 15:09:34 2016
UPTIME: 05:06:18
LOAD AVERAGE: 7.56, 3.49, 1.38
TASKS: 202
NODENAME: apm-mustang-ev3-07.khw.lab.eng.bos.redhat.com
RELEASE: 4.5.0-0.38.el7.aarch64
VERSION: #1 SMP Thu May 19 15:37:24 EDT 2016
MACHINE: aarch64 (unknown Mhz)
MEMORY: 16 GB
PANIC: "sysrq: SysRq : Trigger a crash"
crash> bt -a
PID: 2546 TASK: ffff8003d5ab9600 CPU: 0 COMMAND: "spin"
#0 [ffff8003ffe33d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe33dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe33f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe33fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b73ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffff911b0c94 SP: 0000fffffee69ca0
X29: 0000fffffee69ca0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000fffffee69bb0
X17: 0000000000420000 X16: 0000ffff911b0ba4 X15: 00000000001815e7
X14: 0000ffff9136ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: da16a3a21e08b5bc X4: 0000000000000000 X3: 00000000004005b0
X2: 0000fffffee69df8 X1: 0000fffffee69de8 X0: 0000000000000001
ORIG_X0: 0000ffff91310000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2513 TASK: ffff8003d925d000 CPU: 1 COMMAND: "bash"
#0 [ffff8003dbf238d0] crash_kexec at ffff8000001486cc
#1 [ffff8003dbf23a20] die at ffff80000009731c
#2 [ffff8003dbf23a50] __do_kernel_fault at ffff8000000a7210
#3 [ffff8003dbf23a90] do_page_fault at ffff80000077b244
#4 [ffff8003dbf23ac0] do_mem_abort at ffff8000000902e8
#5 [ffff8003dbf23b30] el1_da at ffff800000091368
PC: ffff8000004970e4 [sysrq_handle_crash+36]
LR: ffff800000497c5c [__handle_sysrq+296]
SP: ffff8003dbf23cf0 PSTATE: 60000145
X29: ffff8003dbf23cf0 X28: ffff8003dbf20000 X27: ffff800000792000
X26: 0000000000000040 X25: 000000000000011e X24: 0000000000000007
X23: 0000000000000000 X22: ffff800000ce4000 X21: 0000000000000063
X20: ffff800000c50000 X19: ffff800000ce4888 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: ffff800000237848 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: ffff800000c50000
X11: 0000000000000000 X10: 00000000000001d3 X9: 00000000000001d4
X8: ffff80000121ce10 X7: 0000000000008d88 X6: ffff8000012140b8
X5: 0000000000000000 X4: 0000000000000000 X3: 0000000000000000
X2: ffff8003ffe76448 X1: 0000000000000000 X0: 0000000000000001
ORIG_X0: 00000000000001d3 SYSCALLNO: 0
#6 [ffff8003dbf23d00] __handle_sysrq at ffff800000497c5c
#7 [ffff8003dbf23d10] write_sysrq_trigger at ffff8000004980d4
#8 [ffff8003dbf23d50] proc_reg_write at ffff80000029b934
#9 [ffff8003dbf23d70] __vfs_write at ffff800000235fd0
#10 [ffff8003dbf23db0] vfs_write at ffff800000236d54
#11 [ffff8003dbf23e40] sys_write at ffff80000023789c
#12 [ffff8003dbf23e90] __sys_trace_return at ffff800000091a8c
PC: 0000ffff7d7dbda8 LR: 0000ffff7d7835d4 SP: 0000fffff90fe1b0
X29: 0000fffff90fe1b0 X28: 0000000000000000 X27: 00000000004fb000
X26: 00000000004bb420 X25: 0000000000000001 X24: 00000000004f8000
X23: 0000000000000000 X22: 0000000000000002 X21: 0000ffff7d881168
X20: 0000ffff76e30000 X19: 0000000000000002 X18: 0000000000000000
X17: 0000ffff7d780e20 X16: 0000000000000000 X15: 00192ea0bab15d05
X14: 0000000000000000 X13: 0000000000000000 X12: 0000000000000001
X11: 000000001c1fc6a0 X10: 00000000004fd000 X9: 0000fffff90fe130
X8: 0000000000000040 X7: 0000000000000001 X6: 0000ffff7d759a98
X5: 0000000000000001 X4: 00000000fbad2a84 X3: 0000000000000000
X2: 0000000000000002 X1: 0000ffff76e30000 X0: 0000000000000001
ORIG_X0: 0000000000000001 SYSCALLNO: 40 PSTATE: 20000000
PID: 2545 TASK: ffff8003d5901d00 CPU: 2 COMMAND: "spin"
#0 [ffff8003ffe93d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffe93dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffe93f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffe93fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4f3ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb50f0c94 SP: 0000ffffe48b4910
X29: 0000ffffe48b4910 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe48b4820
X17: 0000000000420000 X16: 0000ffffb50f0ba4 X15: 00000000001815e7
X14: 0000ffffb52affb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: 46c7b691c219cb7a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe48b4a68 X1: 0000ffffe48b4a58 X0: 0000000000000001
ORIG_X0: 0000ffffb5250000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2541 TASK: ffff8003d917b300 CPU: 3 COMMAND: "usex"
#0 [ffff8003ffec3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffec3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffec3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffec3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbecbed0 fp: 0 (?)
PC: 00000000004361e0 LR: 0000000000435be0 SP: 0000ffffcee64ac0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000062a44 X18: 0000ffffcee64980
X17: 0000ffff8c891b9c X16: 00000000004602b8 X15: 002c4612d8986fa7
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000b5585 X10: 000000005750846e X9: 00000000001ecba2
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 0000000000000032 X3: 0000000000000007
X2: 0000000000000007 X1: 0000000000000005 X0: 00000000004b21cc
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 80000000
PID: 2544 TASK: ffff8003d9176a80 CPU: 4 COMMAND: "usex"
#0 [ffff8003ffef3d60] crash_save_cpu at ffff800000148444
#1 [ffff8003ffef3dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003ffef3f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003ffef3fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbea7ed0 fp: 0 (?)
PC: 0000000000435e38 LR: 0000000000435c94 SP: 0000ffffcee64af0
X29: 0000ffffcee64af0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000041b82 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0034caab9974abe0
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d83c1 X10: 000000005750846e X9: 00000000001eccc0
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 0000000000000042 X1: 000000000000002a X0: 0000ffffcee64b84
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 20000000
PID: 2547 TASK: ffff8003d5906580 CPU: 5 COMMAND: "spin"
#0 [ffff8003fff23d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff23dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff23f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff23fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003db4efed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffb33d0c94 SP: 0000ffffe5813a70
X29: 0000ffffe5813a70 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffe5813980
X17: 0000000000420000 X16: 0000ffffb33d0ba4 X15: 00000000001815e7
X14: 0000ffffb358ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: f72609a0900e9af5 X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffe5813bc8 X1: 0000ffffe5813bb8 X0: 0000000000000001
ORIG_X0: 0000ffffb3530000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
PID: 2542 TASK: ffff8003d9178780 CPU: 6 COMMAND: "usex"
#0 [ffff8003fff53d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff53dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff53f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff53fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003dbebbed0 fp: 0 (?)
PC: 0000000000435e10 LR: 0000000000435ddc SP: 0000ffffcee64ad0
X29: 0000ffffcee64ad0 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 00000000004037b0
X20: 0000ffff8c790000 X19: 0000000000054c83 X18: 0000ffffcee64980
X17: 0000ffff8c894590 X16: 0000000000460008 X15: 0033b1eeb687fcdc
X14: 0000000000000000 X13: 00000003e8000000 X12: 0000000000000018
X11: 00000000000d3be2 X10: 000000005750846e X9: 00000000001ecc9a
X8: 0000000000000099 X7: 0000000000000000 X6: 0000ffff8c8946ec
X5: 0000ffff8c894768 X4: 000000000000474e X3: 0000000000435ff8
X2: 000000003693b600 X1: 000000003693b5f0 X0: 0000000000000006
ORIG_X0: 0000ffffcee64b18 SYSCALLNO: ffffffffffffffff PSTATE: 80000000
PID: 2548 TASK: ffff8003d5ab4d80 CPU: 7 COMMAND: "spin"
#0 [ffff8003fff83d60] crash_save_cpu at ffff800000148444
#1 [ffff8003fff83dc0] handle_IPI at ffff80000009c8d0
#2 [ffff8003fff83f80] gic_handle_irq at ffff8000000904c8
#3 [ffff8003fff83fd0] el0_irq_naked at ffff80000009180c
bt: WARNING: arm64_unwind_frame: on IRQ stack: oriq_sp: ffff8003d5b63ed0 fp: 0 (?)
PC: 00000000004005b0 LR: 0000ffffae060c94 SP: 0000ffffcf219e20
X29: 0000ffffcf219e20 X28: 0000000000000000 X27: 0000000000000000
X26: 0000000000000000 X25: 0000000000000000 X24: 0000000000000000
X23: 0000000000000000 X22: 0000000000000000 X21: 0000000000400450
X20: 0000000000000000 X19: 0000000000000000 X18: 0000ffffcf219d30
X17: 0000000000420000 X16: 0000ffffae060ba4 X15: 00000000001815e7
X14: 0000ffffae21ffb8 X13: 000000000000000f X12: 0000000000000090
X11: 0000000090000000 X10: 00000000ffffffff X9: 0000000000000018
X8: 2f2f2f2f2f2f2f2f X7: b0bca0bdbeb3ff91 X6: 0000000000000000
X5: aa704cb48aa4536a X4: 0000000000000000 X3: 00000000004005b0
X2: 0000ffffcf219f78 X1: 0000ffffcf219f68 X0: 0000000000000001
ORIG_X0: 0000ffffae1c0000 SYSCALLNO: ffffffffffffffff PSTATE: 60000000
crash>
Given that the link at the top of each of the IRQ stacks back to the
kernel-entry-from-user-space exception frames look to be legitimate, perhaps
the "fp: 0" could be used as a key to recognizing the IRQ-while-in-user-space
scenario? And also it doesn't appear that the phantom exception frames
that are dumped in your vmcore are mistakenly generating the fp of 0.
Thanks,
Dave
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