From: Jason Gunthorpe <jgg@nvidia.com>
To: David Hildenbrand <david@redhat.com>
Cc: Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Sean Christopherson <seanjc@google.com>,
Oscar Salvador <osalvador@suse.de>,
Axel Rasmussen <axelrasmussen@google.com>,
linux-arm-kernel@lists.infradead.org, x86@kernel.org,
Will Deacon <will@kernel.org>, Gavin Shan <gshan@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>, Zi Yan <ziy@nvidia.com>,
Andrew Morton <akpm@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Ingo Molnar <mingo@redhat.com>,
Alistair Popple <apopple@nvidia.com>,
Borislav Petkov <bp@alien8.de>,
Thomas Gleixner <tglx@linutronix.de>,
kvm@vger.kernel.org, Dave Hansen <dave.hansen@linux.intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Yan Zhao <yan.y.zhao@intel.com>
Subject: Re: [PATCH 06/19] mm/pagewalk: Check pfnmap early for folio_walk_start()
Date: Mon, 19 Aug 2024 09:19:26 -0300 [thread overview]
Message-ID: <20240819121926.GG2032816@nvidia.com> (raw)
In-Reply-To: <d311645d-9677-44ca-9d86-6d37f971082c@redhat.com>
On Fri, Aug 16, 2024 at 07:56:30PM +0200, David Hildenbrand wrote:
> I think KVM does something nasty: if it something with a "struct page", and
> it's not PageReserved, it would take a reference (if I get
> kvm_pfn_to_refcounted_page()) independent if it's a "normal" or "not normal"
> page -- it essentially ignores the vm_normal_page() information in the page
> tables ...
Oh that's nasty. Nothing should be upgrading the output of the follow
functions to refcounted. That's what GUP is for.
And PFNMAP pages, even if they have struct pages for some reason,
should *NEVER* be refcounted because they are in a PFNMAP VMA. That is
completely against the whole point :\ If they could be safely
refcounted then it would be a MIXEDMAP.
Jason
next prev parent reply other threads:[~2024-08-19 12:19 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-09 16:08 [PATCH 00/19] mm: Support huge pfnmaps Peter Xu
2024-08-09 16:08 ` [PATCH 01/19] mm: Introduce ARCH_SUPPORTS_HUGE_PFNMAP and special bits to pmd/pud Peter Xu
2024-08-09 16:34 ` David Hildenbrand
2024-08-09 17:16 ` Peter Xu
2024-08-09 18:06 ` David Hildenbrand
2024-08-09 16:08 ` [PATCH 02/19] mm: Drop is_huge_zero_pud() Peter Xu
2024-08-09 16:34 ` David Hildenbrand
2024-08-14 12:38 ` Jason Gunthorpe
2024-08-09 16:08 ` [PATCH 03/19] mm: Mark special bits for huge pfn mappings when inject Peter Xu
2024-08-14 12:40 ` Jason Gunthorpe
2024-08-14 15:23 ` Peter Xu
2024-08-14 15:53 ` Jason Gunthorpe
2024-08-09 16:08 ` [PATCH 04/19] mm: Allow THP orders for PFNMAPs Peter Xu
2024-08-14 12:40 ` Jason Gunthorpe
2024-08-09 16:08 ` [PATCH 05/19] mm/gup: Detect huge pfnmap entries in gup-fast Peter Xu
2024-08-09 16:23 ` David Hildenbrand
2024-08-09 16:59 ` Peter Xu
2024-08-14 12:42 ` Jason Gunthorpe
2024-08-14 15:34 ` Peter Xu
2024-08-14 12:41 ` Jason Gunthorpe
2024-08-09 16:08 ` [PATCH 07/19] mm/fork: Accept huge pfnmap entries Peter Xu
2024-08-09 16:32 ` David Hildenbrand
2024-08-09 17:15 ` Peter Xu
2024-08-09 17:59 ` David Hildenbrand
2024-08-12 18:29 ` Peter Xu
2024-08-12 18:50 ` David Hildenbrand
2024-08-12 19:05 ` Peter Xu
2024-08-09 16:08 ` [PATCH 08/19] mm: Always define pxx_pgprot() Peter Xu
2024-08-14 13:09 ` Jason Gunthorpe
2024-08-14 15:43 ` Peter Xu
2024-08-09 16:08 ` [PATCH 09/19] mm: New follow_pfnmap API Peter Xu
2024-08-14 13:19 ` Jason Gunthorpe
2024-08-14 18:24 ` Peter Xu
2024-08-14 22:14 ` Jason Gunthorpe
2024-08-15 15:41 ` Peter Xu
2024-08-15 16:16 ` Jason Gunthorpe
2024-08-15 17:21 ` Peter Xu
2024-08-15 17:24 ` Jason Gunthorpe
2024-08-15 18:52 ` Peter Xu
2024-08-16 23:12 ` Sean Christopherson
2024-08-17 11:05 ` David Hildenbrand
2024-08-21 19:10 ` Peter Xu
2024-08-09 16:09 ` [PATCH 10/19] KVM: Use " Peter Xu
2024-08-09 17:23 ` Axel Rasmussen
2024-08-12 18:58 ` Peter Xu
2024-08-12 22:47 ` Axel Rasmussen
2024-08-12 23:44 ` Sean Christopherson
2024-08-14 13:15 ` Jason Gunthorpe
2024-08-14 14:23 ` Sean Christopherson
2024-08-09 16:09 ` [PATCH 11/19] s390/pci_mmio: " Peter Xu
2024-08-09 16:09 ` [PATCH 12/19] mm/x86/pat: Use the new " Peter Xu
2024-08-09 16:09 ` [PATCH 13/19] vfio: " Peter Xu
2024-08-14 13:20 ` Jason Gunthorpe
2024-08-09 16:09 ` [PATCH 14/19] acrn: " Peter Xu
2024-08-09 16:09 ` [PATCH 15/19] mm/access_process_vm: " Peter Xu
2024-08-09 16:09 ` [PATCH 16/19] mm: Remove follow_pte() Peter Xu
2024-08-09 16:09 ` [PATCH 17/19] mm/x86: Support large pfn mappings Peter Xu
2024-08-09 16:09 ` [PATCH 18/19] mm/arm64: " Peter Xu
2024-08-09 16:09 ` [PATCH 19/19] vfio/pci: Implement huge_fault support Peter Xu
2024-08-14 13:25 ` Jason Gunthorpe
2024-08-14 16:08 ` Alex Williamson
2024-08-14 16:24 ` Jason Gunthorpe
[not found] ` <20240809160909.1023470-7-peterx@redhat.com>
2024-08-09 16:20 ` [PATCH 06/19] mm/pagewalk: Check pfnmap early for folio_walk_start() David Hildenbrand
2024-08-09 16:54 ` Peter Xu
2024-08-09 17:25 ` David Hildenbrand
2024-08-09 21:37 ` Peter Xu
2024-08-14 13:05 ` Jason Gunthorpe
2024-08-16 9:30 ` David Hildenbrand
2024-08-16 14:21 ` Peter Xu
2024-08-16 17:38 ` Jason Gunthorpe
2024-08-21 18:42 ` Peter Xu
2024-08-16 17:56 ` David Hildenbrand
2024-08-19 12:19 ` Jason Gunthorpe [this message]
2024-08-19 14:19 ` Sean Christopherson
2024-08-09 18:12 ` [PATCH 00/19] mm: Support huge pfnmaps David Hildenbrand
2024-08-14 12:37 ` Jason Gunthorpe
2024-08-14 14:35 ` Sean Christopherson
2024-08-14 14:42 ` Paolo Bonzini
2024-08-14 14:43 ` Jason Gunthorpe
2024-08-14 20:54 ` Sean Christopherson
2024-08-14 22:00 ` Sean Christopherson
2024-08-14 22:10 ` Jason Gunthorpe
2024-08-14 23:36 ` Oliver Upton
2024-08-14 23:27 ` Oliver Upton
2024-08-14 23:38 ` Oliver Upton
2024-08-15 0:23 ` Sean Christopherson
2024-08-15 19:20 ` Peter Xu
2024-08-16 3:05 ` Kefeng Wang
2024-08-16 14:33 ` Peter Xu
2024-08-19 13:14 ` Kefeng Wang
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