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[209.85.208.48]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a780a6dfa93sm274415966b.65.2024.07.11.12.17.57 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Jul 2024 12:17:57 -0700 (PDT) Received: by mail-ed1-f48.google.com with SMTP id 4fb4d7f45d1cf-58b3fee65d8so1696743a12.3 for ; Thu, 11 Jul 2024 12:17:57 -0700 (PDT) X-Forwarded-Encrypted: i=1; AJvYcCVIJ4W82jl+rWzBdNGJaJAWFNju+rSL1X+Lw3osA0JTDmFLntviVgkhxLS8ORl6dsJimDyVXusYFXADBuspI++2Si4= X-Received: by 2002:a05:6402:2707:b0:57d:10c:6c40 with SMTP id 4fb4d7f45d1cf-594ba98e3c7mr6937905a12.7.1720725476855; Thu, 11 Jul 2024 12:17:56 -0700 (PDT) MIME-Version: 1.0 References: <20240709130513.98102-1-Jason@zx2c4.com> <20240709130513.98102-2-Jason@zx2c4.com> <378f23cb-362e-413a-b221-09a5352e79f2@redhat.com> <9b400450-46bc-41c7-9e89-825993851101@redhat.com> <37da7835-0d76-463e-b074-455e405b138b@redhat.com> In-Reply-To: <37da7835-0d76-463e-b074-455e405b138b@redhat.com> From: Linus Torvalds Date: Thu, 11 Jul 2024 12:17:40 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always lazily freeable mappings To: David Hildenbrand Cc: "Jason A. Donenfeld" , linux-kernel@vger.kernel.org, patches@lists.linux.dev, tglx@linutronix.de, linux-crypto@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, Greg Kroah-Hartman , Adhemerval Zanella Netto , "Carlos O'Donell" , Florian Weimer , Arnd Bergmann , Jann Horn , Christian Brauner , David Hildenbrand , linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: 51B951C0010 X-Stat-Signature: eckz79ej69h5ufoodzqtnijzxjo9ro7p X-HE-Tag: 1720725481-711028 X-HE-Meta: U2FsdGVkX1+niQscRue6v9EtHvcjgNBJcDVhOcy4nr+F+wjiteu94NjcB5JDr5IDV3nd/8YWJjs654JFlXeETv1a2CiK89U/yEPdPV4pOaJYoQiDAUzEahfeunbVKjA15jnuw6BrDbk2Hkinp1la5ToSBx8y69CBMuUd7eG1N2zvuUkph+8y2a7PeDkJVBwtWHE/6z1k5vv8BBFtXFzH5Sd4w21gC91ihWsRFWG/tlZ/dTxyYe7KEZGSXhuD0CI73HDkouQz0/VklYDbbl4aNTH9X+2e676mpGeW+E2QXOQBBAi1OZFYyLjBUPz97lWYuIK9Xm4lr+Xu9nFya6xMJA80uWJVqhmc6paWh8mTGFI1itKDTJJcUG98L/ChWiLziiJHhDIrAo5XX6AO1ukSXJ+rkIZWG0SYRZ6BCxDw/5U2D+pGyaGqhAaA8SmTlrBufOjKYy8Bl3XUgZHHUO3MtqeYLc+l9h2MNPC38nPJHfXckm54N2qbeJoDQGq0qyMzk88TApWeh6l4D95hLZUbfDHPIU24u/InNbqdV/8JnaT/zJWiJYVf5CTiqrQqNKVsdeaOd1t5K1oXwmsDLdfnATNEsebVe+3/rreSMO4ZZNYnLwdOyXsep8visxg1KCmQUVJU5D3aypcxKAi4Ho954ClwcQDn7yktQKMKGUcdrbVxaiUIkLhIurwdDaIENcpdkiDr8V7n6FHRRHbqXa5PtypfFy3ptRc39zkQNpW3zi1xXP39gYCUoFdsrDYCSiCsrCnVR3HS4xqlFNqWhaBIxjI2Bd/GHj72tYbhl3E7ViRSjHorvTXlWL6unDfStgnaXfDwpQJaX0KMjoEVFLadocJYSnb0cL6zznk/NajEg6Eap281zy9TZOEDWcHL5nGqs1T78BW/38F1n7HmkVeivHo2ydYHqmlHCijUn0FfToenCYk3WOTUMtJeN98Gqw73dpwfwwt64AA7wGr0Ls3 +XZp7SdE 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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, 11 Jul 2024 at 12:08, David Hildenbrand wrote: > > We also have these folio_mark_dirty() calls, for example in > unpin_user_pages_dirty_lock(). Hm ... so preventing the folio from > getting dirtied is likely shaky. I do wonder if we should just disallow page pinning for these pages entirely. When the page can get replaced by zeroes at any time, pinning it doesn't make much sense. Except we do have that whole "fast" case that intentionally doesn't take locks and doesn't have a vma. Darn. Linus