From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-m155116.qiye.163.com (mail-m155116.qiye.163.com [101.71.155.116]) (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 DAB0B526A82; Tue, 29 Sep 2026 13:06:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=101.71.155.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790687176; cv=none; b=pHYg+E1+alSW1Ei2HhSEP9lXAoDOmZ4n9feGE9xGHEiH9nw2EIEhYXnt1tkhNyICRICoaYu9HrP5VUc/HrpK6LVMJSsIhA3b2WzCWRjx0ArnPGg3XgsYuvFG8hxj8FO5pYpEi1h9JxNdjmNSxQ06wElKrqNVQHOk24buEbLBuyM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790687176; c=relaxed/simple; bh=4URAN5FNzJqUrmdB2RD2kXH3bcqOZ15omLjrDbZ/OsM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=c34Z+k30l18cYw2DjvtBErrc9JWUoG4KtJeOPhPiO6x1r/FBxD3IAC0Ya9V2XsfIPP0+ZHxK7V18VuHyelZl5RB6AOosC49YXSM15DjPPMpaeFGE3szxJo31c+DPy/KhZ+xjIb8S8pkhrlrRH8d/g0kWI9XxnaIVohphDjsS0qo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deepseek.com; spf=pass smtp.mailfrom=deepseek.com; dkim=pass (1024-bit key) header.d=deepseek.com header.i=@deepseek.com header.b=XQeEEh97; arc=none smtp.client-ip=101.71.155.116 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=deepseek.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=deepseek.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=deepseek.com header.i=@deepseek.com header.b="XQeEEh97" Received: from deepseek.com (unknown [61.164.44.162]) by smtp.qiye.163.com (Hmail) with ESMTP id 4f8281338; Tue, 29 Sep 2026 20:50:31 +0800 (GMT+08:00) From: Jialiang Huang To: xiang@kernel.org Cc: baohua@kernel.org, damon@lists.linux.dev, david@kernel.org, huang-jl@deepseek.com, kunwu.chan@gmail.com, lance.yang@linux.dev, lianux.mm@gmail.com, linux-mm@kvack.org, mst@redhat.com, ryncsn@gmail.com, sj@kernel.org, virtualization@lists.linux.dev, xueyuan.chen21@gmail.com Subject: Re: [FYI] DAMON and virtio-balloon in DeepSeek's DSec paper Date: Tue, 29 Sep 2026 20:50:30 +0800 Message-ID: <20260929125030.1411980-1-huang-jl@deepseek.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: virtualization@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-HM-Tid: 0aa0ed377a8e09cekunmd46573a965f4dd X-HM-MType: 1 X-HM-Spam-Status: e1kfGhgUHx5ZQUpXWQgPGg8OCBgUHx5ZQUlOS1dZFg8aDwILHllBWSg2Ly tZV1koWUFITzdXWRgWCB1ZQUpXWS1ZQUlXWQ8JGhUIEh9ZQVkZTx1DVhpKTE1IHhoaGE5CHlYVFA kWGhdVEwETFhoSFyQUDg9ZV1kYEgtZQVlNSlVKTU9VT09VSk1JWVdZFhoPEhUdFFlBWU9LSFVCQk lOS1VKS0tVSkJLQlkG DKIM-Signature: a=rsa-sha256; b=XQeEEh97ZWY5l5j1XqrZzUlvgTzY4NwurlzEV94OlooafpzLTNgVszlbD0jU9A7ekpsCD+3QqRz9T08bOYrlo/9DD7klOyalW5AYm0SzHoUr/5K5zjc2K4xpDJDY8Ka1NNnqDlD7N0xJcdf4J1YnZpmzQUzJg1l6eTlLoiGfvcI=; s=default; c=relaxed/relaxed; d=deepseek.com; v=1; bh=4URAN5FNzJqUrmdB2RD2kXH3bcqOZ15omLjrDbZ/OsM=; h=date:mime-version:subject:message-id:from; >> Muchun's vmemmap work is also interesting to us. My understanding is >> that it allocates private backing for struct page metadata on demand, >> which could help reduce the upfront memory overhead for large images. > > Although I haven't had a chance and time to look into that, the main > concern from me is that mmap() access will call > "dax_fault_iter->vmemmap_materialize_page()", and malicious sandbox > workloads (or not malicious, just valid mmap workloads) can cause guest > memory OOMs due to "struct page balloon" for large rootfs in the worst > cases and cause the follow-up mmap access failure, because the guest > memory size may not even fulfill "struct page" for large rootfs. > > Thanks, > Gao Xiang Agreed, if a workload actually accesses a sufficiently large range of the image, allocating struct page metadata on demand could indeed exhaust guest memory. Best, Jialiang Huang