[PATCH v8 3/7] mm, devm_memremap_pages: Fix shutdown handling

[Logan Gunthorpe]

On 2018-11-30 3:28 p.m., Dan Williams wrote:
> On Fri, Nov 30, 2018 at 2:19 PM Logan Gunthorpe <logang at deltatee.com> wrote:
>>
>> Hey,
>>
>> On 2018-11-29 11:51 a.m., Dan Williams wrote:
>>> Got it, let me see how bad moving arch_remove_memory() turns out,
>>> sounds like a decent approach to coordinate multiple users of a single
>>> ref.
>>
>> I've put together a patch set[1] that fixes all the users of
>> devm_memremap_pages() without moving arch_remove_memory(). It's pretty
>> clean except for the p2pdma case which is fairly tricky but I don't
>> think there's an easy way around that.
> 
> The solution I'm trying is to introduce a devm_memremap_pages_remove()
> that each user can call after they have called percpu_ref_exit(), it's
> just crashing for me currently...

Ok, that's probably less of a clean up for other users, but sounds like
it would be less tricky for p2pdma. I'd have to create a list of all
pgmaps, but that's not so hard and doesn't create any nasty races to
consider like my current solution.

>> If you come up with a better solution that's great, otherwise let me
>> know and I'll do some clean up and more testing and send this set to the
>> lists. Though, we might need to wait for your patch to land before we
>> can properly send the fix to it (the first patch in my series)...
> 
> I'd say go ahead and send it. We can fix p2pdma as a follow-on. Send
> it to Andrew as a patch relative to the current -next tree.

Ok, though, how do I reference the current patch in Andrew's tree? Or
does it matter?

Logan