From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4EC92386561 for ; Fri, 27 Mar 2026 19:31:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774639880; cv=none; b=Leg846ot+LvqzFJSd5o2uMU2ChdVcak2arxe8/2ZpP8DnEeG+jP4dEXKDAlTS5PXRWuU6ln/XtZM+KWW/ua3V2UpPL1WOKpvVVVMwIB5LV0MMs0xIiIsxwvD+m+Z7dUF+zUKb1Yb1Yg3tHheNWUkIozBkqbtUdjlAbEYAjIwDYE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774639880; c=relaxed/simple; bh=+3SzXS/yxWjVX5Q80XaoPY9MGqSGzroOg4bwjGy2F4c=; h=Mime-Version:Content-Type:Date:Message-Id:Subject:Cc:To:From: References:In-Reply-To; b=IGHWp/nmF9uSjjT0NhdVUy6+Rzh0zjOw7jfPoyNAxjnFU9ZiFLOfKPPsJ14vv7v71awaznZrOYPrhW7850vorwYbw1Da7xnUE83CpxtgavZeAREQc3E6qbPUBzd/ruqk1C7W/9AVuDyQFqLJyeQYVKrKmserP2gUKMwLRa7o4Oo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AUtlnl4j; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AUtlnl4j" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 605A3C19423; Fri, 27 Mar 2026 19:31:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774639879; bh=+3SzXS/yxWjVX5Q80XaoPY9MGqSGzroOg4bwjGy2F4c=; h=Date:Subject:Cc:To:From:References:In-Reply-To:From; b=AUtlnl4jO5rHk4LN3cdPRtT0NTkQtM7bu71WJgsbbe00t/zR0TDzeiPtUEVrnPez/ 3dsW8oL4dC4JcysU/UYcJYzLxQhwUXWBLd/oVrUCr7Su+Oem3g1z1ZouNGqKoEgdXh CF2+fAhFxILPhe5pW9deMoIdDLrJr1sL9dh3avl4qcF0mEJxCjNyYEo6ODBuotS79N /KgHnsqp5EtPPDYy7C0PFl5sK0scNlix8NQ2TRqBU2oKPpfH8yViu57q9SiNsgRB2r s+hxY7cZFRUF2rPoP3wytmzOLYPekY9ibUNOpuLgC6Cwn7bK9Admq7A9VjSrXjUO8K yX/by8BT8LNlQ== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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> 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.