Re: [RFC PATCH 1/2] ARM: mm: support memory-failure

["Arnd Bergmann" <arnd@arndb.de>]

On Mon, Sep 22, 2025, at 10:28, Xie Yuanbin wrote:
>> It would be helpful to be more specific about what you
>> want to do with this.
>> 
>> Are you working on a driver that would actually make use of
>> the exported interface?
>
> Thanks for your reply.
>
> Yes, In fact, we have developed a hardware component to detect DDR bit
> transitions (software does not sense the detection behavior). Once a bit
> transition is detected, an interrupt is reported to the CPU.
>
> On the software side, we have developed a driver module ko to register
> the interrupt callback to perform soft page offline to the corresponding
> physical pages.
>
> In fact, we will export `soft_offline_page` for ko to use (we can ensure
> that it is not called in the interrupt context), but I have looked at the
> code and found that `memory_failure_queue` and `memory_failure` can also
> be used, which are already exported.

Ok

>> I see only a very small number of
>> drivers that call memory_failure(), and none of them are
>> usable on Arm.
>
> I think that not all drivers are in the open source kernel code.
> As far as I know, there should be similar third-party drivers in other
> architectures that use memory-failure functions, like x86 or arm64.
> I am not a specialist in drivers, so if I have made any mistakes,
> please correct me.

I'm not familiar with the memory-failure support, but this sounds
like something that is usually done with a drivers/edac/ driver.
There are many SoC specific drivers, including for 32-bit Arm
SoCs.

Have you considered adding an EDAC driver first? I don't know
how the other platforms that have EDAC drivers handle failures,
but I would assume that either that subsystem already contains
functionality for taking pages offline, or this is something
that should be done in a way that works for all of them without
requiring an extra driver.

      Arnd