Re: [GIT PULL] x86 fixes

Ingo Molnar
2015-08-19T06:15:27Z

* Ingo Molnar <mingo@kernel.org> wrote:

> So I went and built 743aa456c1834f76 with ARCH=i386 defconfig +MATH_EMULATION=y
> and booted it on real hardware with and without 'no387':
>
> - 743aa456c1834f76: boots fine to a generic distro
> - 743aa456c1834f76 + no387: early crash
>
> the early crash is similar to what I saw when doing the recent FPU changes (and
> which crash I fixed):

Hm, so that crash is back again with the latest kernel:

[ 0.000000] EIP is at kmem_cache_alloc+0x25/0x110
...
[ 0.000000] [<c020a11f>] init_fpu+0x7f/0xc0
[ 0.000000] [<c0730df5>] math_emulate+0x6b5/0xc90
[ 0.000000] [<c0227440>] ? early_serial_putc+0x60/0x60
[ 0.000000] [<c02359cc>] ? call_console_drivers.constprop.14+0x8c/0xe0
[ 0.000000] [<c0258c05>] ? up+0x25/0x50
[ 0.000000] [<c02366e5>] ? console_unlock+0x305/0x4d0
[ 0.000000] [<c0258b06>] ? process_srcu+0x56/0xb0
[ 0.000000] [<c08b0d20>] ? do_debug+0x160/0x160
[ 0.000000] [<c08b0d58>] do_device_not_available+0x38/0x60
[ 0.000000] [<c08b0752>] error_code+0x5a/0x60
[ 0.000000] [<c08b0d20>] ? do_debug+0x160/0x160
[ 0.000000] [<c08a29e7>] ? fpu_init+0xd9/0xf7
[ 0.000000] [<c08a475e>] cpu_init+0x237/0x23f
[ 0.000000] [<c0b324f2>] trap_init+0x243/0x24b
[ 0.000000] [<c0b30759>] start_kernel+0x143/0x2d4
[ 0.000000] [<c0b302a0>] i386_start_kernel+0x76/0x7b

I suspect due to:

5aaeb5c01c5b x86/fpu, sched: Introduce CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT and use it on x86
0c8c0f03e3a2 x86/fpu, sched: Dynamically allocate 'struct fpu'

Thanks,

Ingo