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From: Dan Williams <dan.j.williams@intel.com>
Date: Fri, 30 Nov 2018 14:28:36 -0800
Message-ID: <CAPcyv4iVCMo29SWM2jhnNTZ5ugYaqjeW_LKe9O2YmeNohwQG3A@mail.gmail.com>
Subject: Re: [PATCH v8 3/7] mm, devm_memremap_pages: Fix shutdown handling
To: Logan Gunthorpe <logang@deltatee.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, stable <stable@vger.kernel.org>,
	=?UTF-8?B?SsOpcsO0bWUgR2xpc3Nl?= <jglisse@redhat.com>,
	Christoph Hellwig <hch@lst.de>, Linus Torvalds <torvalds@linux-foundation.org>,
	Linux MM <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Maling list - DRI developers <dri-devel@lists.freedesktop.org>, Bjorn Helgaas <bhelgaas@google.com>,
	Stephen Bates <sbates@raithlin.com>
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On Fri, Nov 30, 2018 at 2:19 PM Logan Gunthorpe <logang@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...

> 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.