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Date: Mon, 1 Feb 2016 16:20:06 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: kernel test robot <ying.huang@linux.intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>, lkp@01.org,
        LKML <linux-kernel@vger.kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Rusty Russell <rusty@rustcorp.com.au>, Michal Marek <mmarek@suse.cz>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Kees Cook <keescook@chromium.org>, Guenter Roeck <linux@roeck-us.net>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>
Subject: Re: [lkp] [kallsyms] bf2d2b07db: kasan: GPF could be caused by
 NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1]
 general protection fault: 0000 [#1] PREEMPT PREEMPT KASANKASAN
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On Thu, 28 Jan 2016 09:12:15 +0800 kernel test robot <ying.huang@linux.intel.com> wrote:

> FYI, we noticed the below changes on
> 
> https://git.linaro.org/people/ard.biesheuvel/linux-arm arm64-kaslr-v4a
> commit bf2d2b07db19001ae0bd55826025b0ba47fae0c2 ("kallsyms: add support for relative offsets in kallsyms address table")
> 
> 
> +-----------------------------------------------------------+------------+------------+
> |                                                           | 2c4d21df0f | bf2d2b07db |
> +-----------------------------------------------------------+------------+------------+
> | boot_successes                                            | 10         | 0          |
> | boot_failures                                             | 6          | 36         |
> | Kernel_panic-not_syncing:Attempted_to_kill_init!exitcode= | 2          |            |
> | IP-Config:Auto-configuration_of_network_failed            | 4          |            |
> | general_protection_fault:#[##]PREEMPT_PREEMPT_KASANKASAN  | 0          | 36         |
> | general_protection_fault:#[##]                            | 0          | 36         |
> | BUG:kernel_boot_hang                                      | 0          | 36         |
> +-----------------------------------------------------------+------------+------------+
> 
> 
> 
> [    0.281636] kasan: CONFIG_KASAN_INLINE enabled
> 
> [    0.282416] kasan: GPF could be caused by NULL-ptr deref or user memory access
> [    0.282416] kasan: GPF could be caused by NULL-ptr deref or user memory accessgeneral protection fault: 0000 [#1] general protection fault: 0000 [#1] PREEMPT PREEMPT KASANKASAN
> 
> [    0.284561] Modules linked in:
> [    0.284561] Modules linked in:
> 
> [    0.285136] CPU: 0 PID: 1 Comm: swapper Not tainted 4.5.0-rc1-00036-gbf2d2b0 #1
> [    0.285136] CPU: 0 PID: 1 Comm: swapper Not tainted 4.5.0-rc1-00036-gbf2d2b0 #1
> [    0.286438] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
> [    0.286438] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Debian-1.8.2-1 04/01/2014
> [    0.288000] task: ffff88000fcb0000 ti: ffff88000fcb8000 task.ti: ffff88000fcb8000
> [    0.288000] task: ffff88000fcb0000 ti: ffff88000fcb8000 task.ti: ffff88000fcb8000
> [    0.289287] RIP: 0010:[<ffffffff8120688c>] 

I'm not sufficiently familiar with KASAN to be able to interpret this. 
Perhaps Andrey can shed some light?

The lack of symbol decoding is a problem.

CONFIG_KALLSYMS=y
CONFIG_KALLSYMS_ALL=y
CONFIG_KALLSYMS_BASE_RELATIVE=y

It should be there.  Perhaps it is not because this error is itself
(possibly) related to kallsyms changes?