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See http://www.infradead.org/rpr.html X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: CAA4E4000D X-Stat-Signature: pdij7waqsdiuj1k3o45s3rffbbu51a1g X-Rspam-User: X-HE-Tag: 1723444763-545486 X-HE-Meta: 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 m+N7PuUd 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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 Thu, Aug 08, 2024 at 12:33:39PM -0600, Martin Oliveira wrote: > This check existed originally due to concerns that P2PDMA needed to copy > fsdax until pgmap refcounts were fixed (see [1]). > > The P2PDMA infrastructure will only call unmap_mapping_range() when the > underlying device is unbound, and immediately after unmapping it waits > for the reference of all ZONE_DEVICE pages to be released before > continuing. This does not allow for a page to be reused and no user > access fault is therefore possible. It does not have the same problem as > fsdax. > > The one minor concern with FOLL_LONGTERM pins is they will block device > unbind until userspace releases them all. This is unfortunately not really minor unless we have a well documented way to force this :(