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Tue, 14 Apr 2026 10:26:56 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Date: Tue, 14 Apr 2026 16:26:36 +0200 From: "Pierre Barre" To: v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org Cc: ericvh@kernel.org, lucho@ionkov.net, asmadeus@codewreck.org, linux_oss@crudebyte.com Message-Id: Subject: [RFC] net/9p: raise MAX_SOCK_BUF beyond 1 MiB for fd/tcp/unix transports? Content-Type: text/plain Content-Transfer-Encoding: 7bit Hi all, MAX_SOCK_BUF in net/9p/trans_fd.c currently caps msize at 1 MiB for the fd/tcp/unix transports. The commit that introduced this ceiling (22bb3b79290e, "net/9p: increase tcp max msize to 1MB") noted that a further bump would need the allocator moved off contiguous slab chunks. That prerequisite appears to be met now: p9_fcall_init() in net/9p/client.c uses kvmalloc() when the transport sets supports_vmalloc = true, which fd/tcp/unix all do. So the original slab fragmentation argument against raising the cap no longer applies to these transports. Before I put together a patch, I wanted to check: 1. Are there other reasons that the 1 MiB cap should stay? 2. If a bump is welcome, is there a target value you'd prefer (e.g. 16 MiB, 32 MiB)? Thanks, Pierre