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Donenfeld" To: David Hildenbrand Cc: Linus Torvalds , 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 Subject: Re: [PATCH v22 1/4] mm: add MAP_DROPPABLE for designating always lazily freeable mappings Message-ID: References: <9b400450-46bc-41c7-9e89-825993851101@redhat.com> <98798483-dfcd-451e-94bb-57d830bf68d8@redhat.com> <54b6de32-f127-4928-9f4a-acb8653e5c81@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: 1E3F21C000F X-Stat-Signature: icdo7kwi59jg6ne3g1fuqxg6nqz8s8gm X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1720720606-663141 X-HE-Meta: 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 wLHPJFaw wwAW/9mfyqIdnI/bgWloBNwHvTx5FH1T7s/aFJc4oeh+zeAFWUqFqv4F8+ZCKsP7/x+3dE9KvZj1TXqxc/+aej5+OUHhsYfMPTdOqou7o5xPrW+OEdo6A9x0ZINVcSZQVHLlKiheSiOEcVWTcqeqBTA8+DH8cWXC02F0creuzvXjD7mS/P8//4CksqQ1IU/OnDy2v2jICq0xP8DskDEYBs8/T9fUKCSeZ8FpGa1r9ghLwntz0ZReICmgpp/H/tz4VEzW+DZqWI/aLoa/QpNqM6vmLZfkZIQoIKaZq3PnLFrt4+PseWqpfxPV0qKtJDixpDJ3zBcGrCXp99TQTl4eYANqKstl4hPb7YGlo5RKMne8scEZjC3ixr4nOBgHTniXZmBa+sNjXNff1IaRjTcVdiHh+IvFXNTtFSQecd1F51F90R6GgNTb1v8QjSrxNQC6Wpmg45OCJCK3L5WY= 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, Jul 11, 2024 at 07:54:34PM +0200, Jason A. Donenfeld wrote: > On Thu, Jul 11, 2024 at 07:27:27PM +0200, David Hildenbrand wrote: > > > PG_owner_priv_1 maps to PG_swapcache? :) > > > > Maybe the combination !swapbacked && swapcache could be used to indicate > > such folios. (we will never set swapbacked) > > > > But likely we have to be a bit careful here. We don't want > > folio_test_swapcache() to return for folios that ... are not in the > > swapcache. > > I was thinking that too, but I'm afraid it's going to be another > whack-a-mole nightmare. Even for things like task_mmu in procfs that > show stats, that's going to be wonky. > > Any other flags we can overload that aren't going to be already used in > our case? PG_error / folio_set_error seems unused in the non-IO case.