Re: [x86/alternatives] 4fc19708b1: kernel_BUG_at_arch/x86/mm/init.c
From: Nadav Amit
Date: Sun May 05 2019 - 04:01:05 EST
> On May 4, 2019, at 11:25 PM, kernel test robot <lkp@xxxxxxxxx> wrote:
>
> FYI, we noticed the following commit (built with gcc-7):
>
> commit: 4fc19708b165c1c152fa1f12f6600e66184b7786 ("x86/alternatives: Initialize temporary mm for patching")
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.kernel.org%2Fcgit%2Flinux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git&data=02%7C01%7Cnamit%40vmware.com%7C42837854d9554a1bfa4608d6d122639e%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C636926342992631859&sdata=41sYsMGJlg0w9t2EP4v9GcxopFVgicOmHfcZXIf91As%3D&reserved=0 master
>
> in testcase: trinity
> with following parameters:
>
> runtime: 300s
>
> test-description: Trinity is a linux system call fuzz tester.
> test-url: https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcodemonkey.org.uk%2Fprojects%2Ftrinity%2F&data=02%7C01%7Cnamit%40vmware.com%7C42837854d9554a1bfa4608d6d122639e%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C636926342992631859&sdata=7ol%2Fq6mrou4H1XuwIaR2T3VOC4dUdyGY3Y%2BtqMUjBZk%3D&reserved=0
>
>
> on test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 2G
>
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
>
>
> +------------------------------------------+------------+------------+
> | | 13585fa066 | 4fc19708b1 |
> +------------------------------------------+------------+------------+
> | boot_successes | 4 | 0 |
> | boot_failures | 0 | 4 |
> | kernel_BUG_at_arch/x86/mm/init.c | 0 | 4 |
> | invalid_opcode:#[##] | 0 | 4 |
> | EIP:poking_init | 0 | 4 |
> | Kernel_panic-not_syncing:Fatal_exception | 0 | 4 |
> +------------------------------------------+------------+------------+
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
>
> [ 5.118979] kernel BUG at arch/x86/mm/init.c:716!
> [ 5.119018] invalid opcode: 0000 [#1] SMP
> [ 5.122979] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.1.0-rc7-00022-g4fc1970 #1
> [ 5.122979] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> [ 5.122979] EIP: poking_init+0x21/0xb8
> [ 5.122979] Code: db 8d 65 f4 5b 5e 5f 5d c3 55 89 e5 53 52 8b 1d f8 2e 5e db 31 eb 81 f3 e3 02 89 18 e8 43 a2 1d ff a3 0c a1 56 db 85 c0 75 02 <0f> 0b d1 c3 c7 05 08 a1 56 db 00 00 00 40 b8 28 1b 48 db e8 82 a9
> [ 5.122979] EAX: 00000000 EBX: 239c2c8f ECX: da865bad EDX: 00000007
> [ 5.122979] ESI: 000003ca EDI: 00000000 EBP: db5bff78 ESP: db5bff70
> [ 5.122979] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00210246
> [ 5.122979] CR0: 80050033 CR2: ffffffff CR3: 1b766000 CR4: 000006b0
> [ 5.122979] Call Trace:
> [ 5.122979] start_kernel+0x447/0x47b
> [ 5.122979] i386_start_kernel+0xd6/0xee
> [ 5.122979] startup_32_smp+0x15f/0x170
> [ 5.122979] Modules linked in:
> [ 5.123041] random: get_random_bytes called from print_oops_end_marker+0x4f/0x60 with crng_init=0
> [ 5.127013] ---[ end trace 790e10dcf838c933 ]---
>
>
> To reproduce:
>
> # build kernel
> cd linux
> cp config-5.1.0-rc7-00022-g4fc1970 .config
> make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 olddefconfig
> make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 prepare
> make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 modules_prepare
> make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 SHELL=/bin/bash
> make HOSTCC=gcc-7 CC=gcc-7 ARCH=i386 bzImage
>
>
> git clone https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fintel%2Flkp-tests.git&data=02%7C01%7Cnamit%40vmware.com%7C42837854d9554a1bfa4608d6d122639e%7Cb39138ca3cee4b4aa4d6cd83d9dd62f0%7C0%7C0%7C636926342992641853&sdata=zTmhr%2FTk12aeE5PPUF6enou4b4Ubqy7JfmO%2FHodsixI%3D&reserved=0
> cd lkp-tests
> bin/lkp qemu -k <bzImage> job-script # job-script is attached in this email
>
>
>
> Thanks,
> lkp
>
> <config-5.1.0-rc7-00022-g4fc1970><job-script.txt><dmesg.xz>
PGD cache should be initialized earlier. I will send a fix shortly.