Re: Crash report: Broken NUMA distance map causes crash on arm64 system

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Oct 30, 2018 at 03:35:35PM +0000, John Garry wrote:
> [    7.154740] ERROR: Node-distance not symmetric
> [    7.154740]
> [    7.160724]   10 15 20 25
> [    7.163456]   15 10 25 30
> [    7.166190]   20 25 10 15
> [    7.168921]   10 10 15 10
> [    7.171655]

But I'm not getting the rest of those errors with my 'reproducer':

  kvm -smp 4 -m 4G -display none -monitor null -serial stdio -kernel defconfig-build/arch/x86/boot/bzImage -append "sched_debug debug ignore_loglevel earlyprintk=serial,ttyS0,115200,keep numa=fake=4:10,15,20,25,15,10,25,30,20,25,10,15,10,10,15,10,0"

[    0.828331] ERROR: Node-distance not symmetric
[    0.828331] 
[    0.829081]   10 15 20 25 
[    0.830079]   15 10 25 30 
[    0.831079]   20 25 10 15 
[    0.832079]   10 10 15 10 
[    0.833079] 
[    0.834373] CPU0 attaching sched-domain(s):
[    0.835082]  domain-0: span=0-3 level=DIE
[    0.836079]   groups: 0:{ span=0 }, 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }
[    0.837082] CPU1 attaching sched-domain(s):
[    0.838081]  domain-0: span=0-3 level=DIE
[    0.839079]   groups: 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }, 0:{ span=0 }
[    0.840082] CPU2 attaching sched-domain(s):
[    0.841080]  domain-0: span=0-3 level=DIE
[    0.842079]   groups: 2:{ span=2 }, 3:{ span=3 }, 0:{ span=0 }, 1:{ span=1 }
[    0.843094] ------------[ cut here ]------------
[    0.844076] kernel BUG at ../mm/slub.c:3901!
[    0.844083] invalid opcode: 0000 [#1] SMP PTI
[    0.845076] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.19.0-rc8+ #305
[    0.845076] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
[    0.845076] RIP: 0010:kfree+0x113/0x160
[    0.845076] Code: 18 48 89 da 4c 89 e6 e8 db 01 c5 00 48 8b 45 00 48 85 c0 75 e4 e9 0e ff ff ff 49 8b 02 f6 c4 80 75 0a 49 8b 42 08 a8 01 75 02 <0f> 0b 49 8b 02 31 f6 f6 c4 80 74 05 41 0f b6 72 51 5b 5d 41 5c 4c
[    0.845076] RSP: 0000:ffffabc080633dc8 EFLAGS: 00010246
[    0.845076] RAX: ffff9f973fff8da0 RBX: ffff9f970000001e RCX: 00000000000000f9
[    0.845076] RDX: 0000000000000000 RSI: ffff9f963ea23c80 RDI: 0000606980000000
[    0.845076] RBP: 0000000000020ac0 R08: 0000000000023c80 R09: ffffffff9f8a10db
[    0.845076] R10: fffff17204000000 R11: 0000000000000001 R12: ffffffff9f8a113d
[    0.845076] R13: 0000000000000003 R14: ffffffffa0ab4820 R15: ffff9f973e5bde00
[    0.845076] FS:  0000000000000000(0000) GS:ffff9f963ea00000(0000) knlGS:0000000000000000
[    0.845076] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.845076] CR2: 00000000ffffffff CR3: 000000008ea0a000 CR4: 00000000000006f0
[    0.845076] Call Trace:
[    0.845076]  destroy_sched_domain+0x3d/0x50
[    0.845076]  cpu_attach_domain+0x378/0x680
[    0.845076]  ? update_group_capacity+0x20/0x2c0
[    0.845076]  build_sched_domains+0xde9/0xed0
[    0.845076]  ? set_debug_rodata+0xc/0xc
[    0.845076]  sched_init_domains+0x80/0x90
[    0.845076]  sched_init_smp+0x1d/0x63
[    0.845076]  kernel_init_freeable+0x101/0x23f
[    0.845076]  ? rest_init+0xb0/0xb0
[    0.845076]  kernel_init+0x5/0x100
[    0.845076]  ret_from_fork+0x35/0x40

I'll work on that crash though..

> I also note that if I apply the patch, below, to reject the invalid NUMA
> distance, we're still getting a warning/error:
> 
> [    7.144407] CPU: All CPU(s) started at EL2
> [    7.148678] alternatives: patching kernel code
> [    7.153557] ERROR: Node-0 not representative
> [    7.153557]
> [    7.159365]   10 15 20 25
> [    7.162097]   15 10 25 30
> [    7.164832]   20 25 10 15
> [    7.167562]   25 30 15 10

Yeah, that's an 'obviously' broken topology too.

Clearly you're far more creative than the ACPI BIOS people have been so
far.