linux-kernel - Re: [GIT PULL] VFIO updates for v6.17-rc1

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Message-ID: <20250805142028.GM184255@nvidia.com>
Date: Tue, 5 Aug 2025 11:20:28 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: David Hildenbrand <david@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lizhe.67@...edance.com" <lizhe.67@...edance.com>
Subject: Re: [GIT PULL] VFIO updates for v6.17-rc1

On Tue, Aug 05, 2025 at 04:10:45PM +0200, David Hildenbrand wrote:
> There are some weird scenarios where you hotplug memory after boot memory,
> and suddenly you can runtime-allocate a gigantic folio that spans both
> ranges etc.

I was thinking we'd forbid this directly, but yes it is a another new
check.

> So while related, the corner cases are all a bit nasty, and just forbidding
> folios to span a memory section on these problematic configs (sparse
> !vmemmap) sounds interesting.

Indeed, this just sounds like forcing MAX_ORDER to be no larger than
the section size for this old mode?

Jason