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dkim=pass header.d=Nvidia.com header.s=selector2 header.b=Sg3qh94m; dmarc=pass (policy=reject) header.from=nvidia.com; spf=none (imf20.hostedemail.com: domain of jgg@nvidia.com has no SPF policy when checking 40.107.236.45) smtp.mailfrom=jgg@nvidia.com X-HE-Tag: 1644977041-580608 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: On Wed, Feb 16, 2022 at 12:23:44PM +1100, Alistair Popple wrote: > Device private and device coherent pages are not marked with pte_devmap and they > are backed by a struct page. The only way of inserting them is via migrate_vma. > The refcount is decremented in zap_pte_range() on munmap() with special handling > for device private pages. Looking at it again though I wonder if there is any > special treatment required in zap_pte_range() for device coherent pages given > they count as present pages. This is what I guessed, but we shouldn't be able to just drop pte_devmap on these pages without any other work?? Granted it does very little already.. I thought at least gup_fast needed to be touched or did this get handled by scanning the page list after the fact? Jason