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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 v21 1/4] mm: add VM_DROPPABLE for designating always lazily freeable mappings Message-ID: References: <1583c837-a4d5-4a8a-9c1d-2c64548cd199@redhat.com> <6705c6c8-8b6a-4d03-ae0f-aa83442ec0ab@redhat.com> <7439da2e-4a60-4643-9804-17e99ce6e312@redhat.com> <75d6c45d-deea-464d-b0fd-b36e5d73b898@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <75d6c45d-deea-464d-b0fd-b36e5d73b898@redhat.com> X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 2480940008 X-Stat-Signature: 67yy1jfoxpw8jnkyditig36w3t75o4fx X-Rspam-User: X-HE-Tag: 1720491491-560376 X-HE-Meta: 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 KlE9696X 6SIA9ErAb7ZMgqY6o5TRWyT+Q0tCZrPTr31d1SLVjNcJ8k3hE75UA7Cm+QXOgp8zZPqU/Zsn1kwalHIiQQaBpOpMhr9/tKhpYg+206DbKRkCxzltJl1TRIwe5zwenFrYHgamAPzAIS/LGHb4rEdja5OxAlPiEbZCZuRFncdqRKnYVQ9+9si6uR46aMAtogG5RNGQ1nJHry3jELA8cvcubgWjhUzwy7pz3X7VzgkXNlZyv+zavyTwaFNLnKESKHkzKZml2USEmomEg062SBhWXR9NZtlh75mFZVVGijlUFVmmCCZdqz68SluKxq34u+Je6+kiMzwSMrrVk0xWU9QB7uBbVTCHLuXyuRktMZI/m2kcLx+PHI4qjlkTSNQCbtMYo+pRtw/WPnm5ce8vrpaP34HTt3by8xuesGLnA3uQfMdoIpPx171chs6Oiaw/zuLz7BjkxsdRCoL5eRWc= 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: Hi David, On Mon, Jul 08, 2024 at 10:21:09PM +0200, David Hildenbrand wrote: > BTW, I was just trying to understand how MADV_FREE + MAP_DROPPABLE would > behave without any swap space around. > > Did you experiment with that? You mean on a system without any swap configured? That's actually my primary test environment for this. It behaves as expected: when ram fills up and the scanner is trying to reclaim what it can, folio_test_swapbacked(folio) is false, and the memory gets freed. After, reads fault in a zero page. So it's working as expected. Jason