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[99.254.121.117]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-44f5b83606asm50621701cf.70.2024.07.17.11.12.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Jul 2024 11:12:51 -0700 (PDT) Date: Wed, 17 Jul 2024 14:12:48 -0400 From: Peter Xu To: David Hildenbrand Cc: Yan Zhao , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Andrew Morton , Alex Williamson , Jason Gunthorpe , Al Viro , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "Kirill A . Shutemov" , "x86@kernel.org" , "Tian, Kevin" , Pei Li , David Wang <00107082@163.com>, Bert Karwatzki , Sergey Senozhatsky Subject: Re: [PATCH] mm/x86/pat: Only untrack the pfn range if unmap region Message-ID: References: <20240712144244.3090089-1-peterx@redhat.com> <116ca902-103d-47cb-baf0-905983baf9bb@redhat.com> <1dc7cf79-4c01-4b1e-be33-49eb2bdb9238@redhat.com> MIME-Version: 1.0 In-Reply-To: <1dc7cf79-4c01-4b1e-be33-49eb2bdb9238@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 66270A002C X-Stat-Signature: qx9bednogfwhsmde5cot717pjdpueetg X-HE-Tag: 1721239976-793750 X-HE-Meta: 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 X2NIIwwQ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jul 17, 2024 at 06:32:05PM +0200, David Hildenbrand wrote: > On 17.07.24 18:30, Peter Xu wrote: > > On Wed, Jul 17, 2024 at 04:17:12PM +0200, David Hildenbrand wrote: > > > I'd be curious how a previous truncation on a file can tear down a PFNMAP > > > mapping -- and if there are simple ways to forbid that (if possible). > > > > Unfortunately, forbiding it may not work for vfio, as vfio would like to > > allow none (or partial) mapping on the bars.. at least so far that's the > > plan. > > I think vfio should handle that memtype reservation manually, as you > proposed. So that shouldn't block that IIUC. Oh, so maybe I misunderstood here. As long as we can live with VFIO's vma (with the pfn tracking on top, but without pgtable installed) I think it should be fine. Thanks, -- Peter Xu