Re: [patch 08/87] proc/vmcore: convert oldmem_pfn_is_ram callback to more generic vmcore callbacks

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On 09.11.21 04:59, Dave Young wrote:
> Hi Andrew,
> On 11/08/21 at 06:31pm, Andrew Morton wrote:
>> From: David Hildenbrand <david@xxxxxxxxxx>
>> Subject: proc/vmcore: convert oldmem_pfn_is_ram callback to more generic vmcore callbacks
>>
>> Let's support multiple registered callbacks, making sure that registering
>> vmcore callbacks cannot fail.  Make the callback return a bool instead of
>> an int, handling how to deal with errors internally.  Drop unused
>> HAVE_OLDMEM_PFN_IS_RAM.
>>
>> We soon want to make use of this infrastructure from other drivers:
>> virtio-mem, registering one callback for each virtio-mem device, to
>> prevent reading unplugged virtio-mem memory.
>>
>> Handle it via a generic vmcore_cb structure, prepared for future
>> extensions: for example, once we support virtio-mem on s390x where the
>> vmcore is completely constructed in the second kernel, we want to detect
>> and add plugged virtio-mem memory ranges to the vmcore in order for them
>> to get dumped properly.
>>
>> Handle corner cases that are unexpected and shouldn't happen in sane
>> setups: registering a callback after the vmcore has already been opened
>> (warn only) and unregistering a callback after the vmcore has already been
>> opened (warn and essentially read only zeroes from that point on).
> 
> This is a nice improvement, thanks David.  But I did not get time to
> review it yet.  The overall idea is good, I would prefer to hold on the
> patches for some time and waiting for more review.
> 
> Sorry for jumping in late.

I really want this in v5.16. Please see the comment in

https://lkml.kernel.org/r/20211006122709.27885-1-david@xxxxxxxxxx

Can we just fix any fallout (if any) as usual after the merge window?

-- 
Thanks,

David / dhildenb





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