Re: b1cbacc866 ("x86/smpboot: Do not use smp_num_siblings in .."): divide error: 0000 [#1] SMP DEBUG_PAGEALLOC

From: Prarit Bhargava
Date: Tue Dec 05 2017 - 07:23:12 EST



On 12/05/2017 03:00 AM, kernel test robot wrote:
> Greetings,
>
> 0day kernel testing robot got the below dmesg and the first bad commit is
>
> https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/urgent
>
> commit b1cbacc8663a4dce62e4ae501e859c82f4aeb1ca
> Author: Prarit Bhargava <prarit@xxxxxxxxxx>
> AuthorDate: Mon Dec 4 11:45:21 2017 -0500
> Commit: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> CommitDate: Mon Dec 4 23:03:48 2017 +0100
>
> x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation
>
> Documentation/x86/topology.txt defines smp_num_siblings as "The number of
> threads in a core". Since commit bbb65d2d365e ("x86: use cpuid vector 0xb
> when available for detecting cpu topology") smp_num_siblings is the
> maximum number of threads in a core. If Simultaneous MultiThreading
> (SMT) is disabled on a system, smp_num_siblings is 2 and not 1 as
> expected.
>
> Use topology_max_smt_threads(), which contains the active numer of threads,
> in the __max_logical_packages calculation.
>

Looking now.

P.

> Fixes: b4c0a7326f5d ("x86/smpboot: Fix __max_logical_packages estimate")
> Reported-by: Jakub Kicinski <kubakici@xxxxx>
> Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Tested-by: Jakub Kicinski <kubakici@xxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx
> Cc: "netdev@xxxxxxxxxxxxxxx"
> Cc: Clark Williams <williams@xxxxxxxxxx>
> Link: https://lkml.kernel.org/r/20171204164521.17870-1-prarit@xxxxxxxxxx
>
> 866a79a1c9 x86/microcode/AMD: Add support for fam17h microcode loading
> b1cbacc866 x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation
> cdf577209a x86/power: Fix some ordering bugs in __restore_processor_context()
> 5b33501b13 Merge branch 'WIP.x86/mm'
> +------------------------------------------+------------+------------+------------+------------+
> | | 866a79a1c9 | b1cbacc866 | cdf577209a | 5b33501b13 |
> +------------------------------------------+------------+------------+------------+------------+
> | boot_successes | 33 | 0 | 0 | 10 |
> | boot_failures | 0 | 15 | 19 | |
> | divide_error:#[##] | 0 | 15 | 19 | |
> | RIP:native_smp_cpus_done | 0 | 15 | 19 | |
> | Kernel_panic-not_syncing:Fatal_exception | 0 | 15 | 19 | |
> +------------------------------------------+------------+------------+------------+------------+
>
> [ 0.025056] smpboot: CPU0: Intel QEMU Virtual CPU version 2.5+ (family: 0x6, model: 0x6, stepping: 0x3)
> [ 0.026373] Performance Events: PMU not available due to virtualization, using software events only.
> [ 0.029102] Hierarchical SRCU implementation.
> [ 0.030040] smp: Bringing up secondary CPUs ...
> [ 0.030528] smp: Brought up 1 node, 1 CPU
> [ 0.030953] divide error: 0000 [#1] SMP DEBUG_PAGEALLOC
> [ 0.031000] Modules linked in:
> [ 0.031000] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.14.0-01223-gb1cbacc #1
> [ 0.031000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> [ 0.031000] task: ffff88001e460000 task.stack: ffffc90000008000
> [ 0.031000] RIP: 0010:native_smp_cpus_done+0x3a/0xd9
> [ 0.031000] RSP: 0000:ffffc9000000bed8 EFLAGS: 00010246
> [ 0.031000] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
> [ 0.031000] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff82645830
> [ 0.031000] RBP: ffffc9000000bee8 R08: 0000000000000000 R09: 0000000000000000
> [ 0.031000] R10: ffff88001e460ce0 R11: 0000000000000001 R12: 000000000000a020
> [ 0.031000] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 0.031000] FS: 0000000000000000(0000) GS:ffff88001f800000(0000) knlGS:0000000000000000
> [ 0.031000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 0.031000] CR2: 00000000ffffffff CR3: 000000000c822000 CR4: 00000000000006b0
> [ 0.031000] Call Trace:
> [ 0.031000] smp_init+0xa4/0xa9
> [ 0.031000] kernel_init_freeable+0x7d/0x1af
> [ 0.031000] ? rest_init+0xc0/0xc0
> [ 0.031000] kernel_init+0x9/0xeb
> [ 0.031000] ret_from_fork+0x24/0x30
> [ 0.031000] Code: 64 82 48 89 e5 41 54 49 c7 c4 20 a0 00 00 53 31 db 42 0f b7 8c 20 d8 00 00 00 8b 05 26 7d de ff 0f af 0d 7b 67 de ff 8d 44 01 ff <f7> f1 89 c6 89 05 75 67 de ff e8 91 55 6b fe e8 96 33 00 00 83
> [ 0.031000] RIP: native_smp_cpus_done+0x3a/0xd9 RSP: ffffc9000000bed8
> [ 0.031004] ---[ end trace 5c005ba3fb078002 ]---
> [ 0.031461] Kernel panic - not syncing: Fatal exception
>
> # HH:MM RESULT GOOD BAD GOOD_BUT_DIRTY DIRTY_NOT_BAD
> git bisect start a2b385361ab06450408875fe58a45445ed300a40 4fbd8d194f06c8a3fd2af1ce560ddb31f7ec8323 --
> git bisect bad 60f97903c07c2f9dec16f3434fa6bc8374553c75 # 07:54 B 0 1 15 0 Merge 'krzk/for-next' into devel-catchup-201712050639
> git bisect bad c5ae250423192c95979baa9e26553078c6fbdb12 # 09:33 B 0 5 19 0 Merge 'linux-review/yuan-linyu/netlink-optimize-err-assignment/20171205-051606' into devel-catchup-201712050639
> git bisect bad d45ca31b78f444ff0f7c6dbd56df9c75991b1748 # 10:16 B 0 6 20 0 Merge 'jcmvbkbc-xtensa/xtensa-ssp-kasan' into devel-catchup-201712050639
> git bisect good 9b490c677dc4246f6f2adad29d94a71a25f492a8 # 10:49 G 10 0 0 1 Merge 'abelloni/at91-dt-fixes' into devel-catchup-201712050639
> git bisect good fcfab2f4b076cdd0c000c2e1a30404e4007c2c06 # 11:13 G 11 0 0 0 Merge 'abelloni/at91-dt' into devel-catchup-201712050639
> git bisect bad b9115db1d525e5a59a515ec6ffc53e5163b53f9b # 11:52 B 0 10 24 0 Merge 'tip/x86/urgent' into devel-catchup-201712050639
> git bisect good 2b67799bdf25d19690710a88c2bce9127cf3ba6f # 12:16 G 10 0 0 0 x86: Make X86_BUG_FXSAVE_LEAK detectable in CPUID on AMD
> git bisect good 866a79a1c98c5004a410122b06f808152f2fe53c # 12:53 G 11 0 0 0 x86/microcode/AMD: Add support for fam17h microcode loading
> git bisect bad 2ee90363a838cf41ebf1ad24bad274762e467d8d # 13:15 B 0 3 17 0 x86 / PCI: Make broadcom_postcore_init() check acpi_disabled
> git bisect bad b1cbacc8663a4dce62e4ae501e859c82f4aeb1ca # 13:39 B 0 1 15 0 x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation
> # first bad commit: [b1cbacc8663a4dce62e4ae501e859c82f4aeb1ca] x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation
> git bisect good 866a79a1c98c5004a410122b06f808152f2fe53c # 13:55 G 31 0 0 0 x86/microcode/AMD: Add support for fam17h microcode loading
> # extra tests with debug options
> git bisect bad b1cbacc8663a4dce62e4ae501e859c82f4aeb1ca # 14:22 B 0 11 25 0 x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation
> # extra tests on HEAD of linux-devel/devel-catchup-201712050639
> git bisect bad a2b385361ab06450408875fe58a45445ed300a40 # 14:22 B 0 21 38 0 0day head guard for 'devel-catchup-201712050639'
> # extra tests on tree/branch tip/x86/urgent
> git bisect bad cdf577209aad4cdbe3455d3efa6cf631f838c55d # 14:37 B 0 1 15 0 x86/power: Fix some ordering bugs in __restore_processor_context()
> # extra tests with first bad commit reverted
> git bisect good 886fa2f68001f51d63c3934943f4a844faaa5e8f # 15:15 G 11 0 0 0 Revert "x86/smpboot: Do not use smp_num_siblings in __max_logical_packages calculation"
> # extra tests on tree/branch tip/master
> git bisect good 5b33501b13ab807284ae73492938d162e0f8629e # 15:59 G 10 0 0 0 Merge branch 'WIP.x86/mm'
>
> ---
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