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b=AUtlnl4jO5rHk4LN3cdPRtT0NTkQtM7bu71WJgsbbe00t/zR0TDzeiPtUEVrnPez/ 3dsW8oL4dC4JcysU/UYcJYzLxQhwUXWBLd/oVrUCr7Su+Oem3g1z1ZouNGqKoEgdXh CF2+fAhFxILPhe5pW9deMoIdDLrJr1sL9dh3avl4qcF0mEJxCjNyYEo6ODBuotS79N /KgHnsqp5EtPPDYy7C0PFl5sK0scNlix8NQ2TRqBU2oKPpfH8yViu57q9SiNsgRB2r s+hxY7cZFRUF2rPoP3wytmzOLYPekY9ibUNOpuLgC6Cwn7bK9Admq7A9VjSrXjUO8K yX/by8BT8LNlQ== Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Fri, 27 Mar 2026 20:31:16 +0100 Message-Id: Subject: Re: [PATCH v8 0/6] mm/vmalloc: free unused pages on vrealloc() shrink Cc: , "Shivam Kalra via B4 Relay" , "Uladzislau Rezki" , , , "Alice Ryhl" To: "Andrew Morton" From: "Danilo Krummrich" References: <20260327-vmalloc-shrink-v8-0-cc6b57059ed7@zohomail.in> <20260327113758.75f04588310a707b4d4b1aac@linux-foundation.org> In-Reply-To: <20260327113758.75f04588310a707b4d4b1aac@linux-foundation.org> X-Rspam-User: X-Rspamd-Queue-Id: 12209180002 X-Stat-Signature: we1ibde7rpsm4i8ip5ef43xquk1qoyou X-Rspamd-Server: rspam06 X-HE-Tag: 1774639880-132207 X-HE-Meta: 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 7T6PtaxC 0cV4leoSgDDFdc1aQuyOdi35oBCqREhtls4HYnxCk9y+FI4Qc1D+3vs51frtj7310EI+df5jGZUintgi5aXCRGa1llQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri Mar 27, 2026 at 7:37 PM CET, Andrew Morton wrote: > Are we able to describe how much memory this change might save under > various scenarios? If the savings are impressively large then that > would get attention. We already have a workaround in place for shrinking vmalloc buffers through= a deep copy in Rust alloc. Given that binder, which motivated this workaround, uses it already, it sug= gests that the savings are significant enough to accept this overhead (I assume A= lice has some numbers). So, I assume the more interesting question would be how badly the deep copy hurts binder compared to unmapping and freeing spare pages.