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b=AEcamcDgQI/AsYPr1XCKo5dgYxuYDyLUh8ZtZaIZ3eW9VTnIuvHyym6sFow+V+EmJ BF/EC2CPLtBSLgmPX6/6yjyEdHeoRDl/w577EI29kncY8HueOnXAfUDmLNu1ATrBK0 9ZHnpUTzm6ZDI+IUC2S3qusrId8dd939bIuBbpV6wqmH5toMuH+v5IRoDmAAIC8NJa ZnCIe/9qy7oR0D+Vma5F7lQV9JJQ/WHEISQwrjawugi+3KAdfa5HZJkwWNdtB4zmLK 6Oj6DMWXxTgkA/N+f109WJn8XhQmPW/lxnxAfz2oaKrLa+dwH1XPSgkyKAkdJZ4FlO V0E1EDno6R1YQ== Date: Sat, 8 Aug 2026 00:19:15 +0000 From: Yosry Ahmed To: Brendan Jackman , Brendan Jackman Cc: Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Vlastimil Babka , Mike Rapoport , Wei Xu , Johannes Weiner , Zi Yan , Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, Sumit Garg , Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Patrick Bellasi , Reiji Watanabe , Sean Christopherson , Nikita Kalyazin Subject: Re: [PATCH v3 03/26] mm: introduce AS_NO_DIRECT_MAP Message-ID: References: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> <20260726-page_alloc-unmapped-v3-3-6f5729aa9832@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260726-page_alloc-unmapped-v3-3-6f5729aa9832@google.com> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: D69C2C0002 X-Stat-Signature: 3ej59ptchz15mspp9dor8mpjjrw9hs8a X-HE-Tag: 1786148359-234840 X-HE-Meta: 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 hyl+yn93 GOp7nPJzGdeDBx58cGipdvaZxjh1ZgbW4+pSW7ko1lwyW0CyjWekqdU/FSVWmCY7xEaC6CjOXLxSpqtr7c3XBK5N2YV+oaJONLoCtvtRVrP7bp8h+av38EEAI8xIO2hx89f2M23pE3Q9hyNpuENLC9QHALbC8nGwcV8pq6M7208JAsfUUtRCJj1PTfkbTylRQTnK3SX9xqY+dmfztcp7IDyT0z++LLDc+Q1lAsQrjGX5X8bv06/K2q9dAHwg1r/SXynGI7R8rRvprt/+obPaTh3w8lrYfMAxZ8UVIf/OvgRFyUj3fAaZL57/uB9Q3pmIbbIDAUI23MFIXwXYaoIgHNIOuaTLM2+oF3syxPD8nbikKY4iXuyIOFSGBhwmneIkpAxSbmm7fSsyws4Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Jul 26, 2026 at 10:22:36PM +0000, Brendan Jackman wrote: > From: Patrick Roy > > Add AS_NO_DIRECT_MAP for mappings where direct map entries of folios are > set to not present. Currently, mappings that match this description are > secretmem mappings (memfd_secret()). Later, some guest_memfd > configurations will also fall into this category. > > Reject this new type of mappings in all locations that currently reject > secretmem mappings, on the assumption that if secretmem mappings are > rejected somewhere, it is precisely because of an inability to deal with > folios without direct map entries, and then make memfd_secret() use > AS_NO_DIRECT_MAP on its address_space to drop its special > vma_is_secretmem()/secretmem_mapping() checks. > > Use a new flag instead of overloading AS_INACCESSIBLE (which is already > set by guest_memfd) because not all guest_memfd mappings will end up > being direct map removed (e.g. in pKVM setups, parts of guest_memfd that > can be mapped to userspace should also be GUP-able, and generally not > have restrictions on who can access it). > > Signed-off-by: Patrick Roy > Signed-off-by: Nikita Kalyazin > [Moved zapping to page cache; removed review tags] > Signed-off-by: Brendan Jackman > --- [..] > /** > * filemap_remove_folio - Remove folio from page cache. > * @folio: The folio. > @@ -260,6 +309,8 @@ void filemap_remove_folio(struct folio *folio) > inode_lru_list_add(mapping->host); > spin_unlock(&mapping->host->i_lock); > > + prep_remove_unmapped_folio(mapping, folio); Does this miss callers that call __filemap_remove_folio() directly? We can't just move the call into __filemap_remove_folio() as it will later include a TLB shootdown and (at least) some of the callers have IRQs disabled. > + > filemap_free_folio(mapping, folio); > }