linux-ext4 - Re: [aarch64] Kernel crash on v5.1-rc5, __arch_copy_from

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Message-ID: <98fad1eb-b033-3c31-9100-bad672b4cfe0@arm.com>
Date:   Wed, 24 Apr 2019 14:50:06 +0100
From:   James Morse <james.morse@....com>
To:     Qu Wenruo <quwenruo.btrfs@....com>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Linux FS Devel <linux-fsdevel@...r.kernel.org>,
        Ext4 <linux-ext4@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [aarch64] Kernel crash on v5.1-rc5,
 __arch_copy_from_user+0x1bc/0x240

Hi Qu,

On 22/04/2019 02:14, Qu Wenruo wrote:
> On 2019/4/21 下午9:28, Matthew Wilcox wrote:
>> On Sun, Apr 21, 2019 at 05:12:50PM +0800, Qu Wenruo wrote:
>>> On 2019/4/21 下午4:20, Qu Wenruo wrote:
>>>> Just hit one crash on v5.1-rc5 kernel, on ext4 filesystem.
>>>
>>> Well, also hit the same one in v5.0.8 kernel.
>>>
>>> Exact the same backtrace.
>>>
>>> Really not sure which part is to blame, ARM or ext4?
>>
>> You probably have faulty hardware:

> I tried memtester, and kernel also crashed.
> 
> Maybe it's really faulty memory or I'm using wrong memory speed.

As another option: there may be no memory at this physical address.
If your board only has 1G of memory, but the bootloader/DT is reporting 2G, you could see
SError like this (assuming this is the first access to that page).

SError can be a fatal interrupt from the hardware, its also how the CPU tells us about
'asynchronous external abort'. In this case it could be an attempt to access a physical
address where nothing exists.


Thanks,

James