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Mon, 19 Oct 2026 12:32:34 -0700 (PDT) Received: from localhost ([153.61.198.247]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ea151a2a06sm4758725ad.73.2026.10.19.12.32.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Oct 2026 12:32:34 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Mon, 19 Oct 2026 19:32:33 +0000 Message-Id: From: "Alexei Starovoitov" To: "Andrea Righi" Cc: "Daniel Borkmann" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Ihor Solodrai" , "John Fastabend" , "Josh Don" , "Vineeth Pillai" , "Balbir Singh" , "Shameer Kolothum" , "Himadri Chhaya-Shailesh" , "NchangRoy" , , Subject: Re: [PATCH bpf-next 0/5] bpf: Expose pinned arenas as sized bpffs files In-Reply-To: References: <20261010224902.1232178-1-arighi@nvidia.com> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Mon, Oct 19, 2026 at 01:44 AM Andrea Righi wrote: > That's fine for a single long-running guest, but with VMs coming and > going the host arena would only grow (this was also Josh's concern about > the high watermark). Would it be ok with an explicit release of an > imported range (clear the ptes, flush, set rt_own back, unpin the > folios)? A BPF prog touching a released range would then hit the usual > arena fault handling, like any unallocated page. make sense to me. In my prototype arena_free_pages() sees the imported range in rt_own. Instead of returning early it can do the above and give the range back to rt.