From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 31AC1112584E for ; Wed, 11 Mar 2026 16:01:47 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4fWFqY4pWHz3bf8; Thu, 12 Mar 2026 03:01:45 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip="2a00:1450:4864:20::649" ARC-Seal: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1773244905; cv=none; b=WOZeiU8yKE0gYf39CzPEt9fERBiXioY98IBnNiPqnwJ4eq8Sacbt2kcwp+F9sznlFTsY15aeBLGhcKtOQ+cgpriZ0LRav+cmxmS2cbU/z/t/BUiPeL+aHQknzsf5SuCrBKD9VmzuH5oFkfnS+fuRV4R2LpIBfFzpL4TKgM7Z2wW7WEqvoiJVL0lF6j35SBOt+n3a80/cAkn0t2kbxiSsztG4KagJbyiatO7a0esH+3ptCL9pwyQNnb5mv/kfIK99P7swvAE9mqobnNLc/AqSx+us7cvUvcqxGkm5YrRw+uZUR24EFiBZwajw5g0WI6oIvC+3vZ6NAJS06syyikM/hg== ARC-Message-Signature: i=1; a=rsa-sha256; d=lists.ozlabs.org; s=201707; t=1773244905; c=relaxed/relaxed; bh=FZ9wJHN98p2eqW+aluFwwdS4VIjV0bOaQ4w+79zBhNs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=EQqSueDq5M6a62EovPoPCTD8th7oAVI0U/YyUCYGhp9oYYwy4HryVUc4Zf9uup1RDIJBNrhwtXdK6xVmwPrfZJCWICt2qzxcAHM5rG35VNsaNFQz4BPqXK1u/HhFRzHEsdJ+TEM5LEYieaEa3yx8abZ2S6VquZPdOiWtJGrj3R0brF4PSgpaS6P7rYkTo6ptvmZgth/AFt4MeyGRhOt6HgGIL3BNvJH2J4wrARXHfHc/o7fvdSFRAqqHrfEf3nG88sXxVvXot5DwrMv/3Xua8W3PovNr1g+mOCHhMaR/j9LbAa8EK5Q0H34V5xJ8frD5/CjzrpkWo8KwsrffG4v9gg== ARC-Authentication-Results: i=1; lists.ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=3deXfe43; dkim-atps=neutral; spf=pass (client-ip=2a00:1450:4864:20::649; helo=mail-ej1-x649.google.com; envelope-from=34pgxaqkkdce7if9boveidlldib.9ljifkrumm9-absifpqp.lwi78p.lod@flex--aliceryhl.bounces.google.com; receiver=lists.ozlabs.org) smtp.mailfrom=flex--aliceryhl.bounces.google.com Authentication-Results: lists.ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20230601 header.b=3deXfe43; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--aliceryhl.bounces.google.com (client-ip=2a00:1450:4864:20::649; helo=mail-ej1-x649.google.com; envelope-from=34pgxaqkkdce7if9boveidlldib.9ljifkrumm9-absifpqp.lwi78p.lod@flex--aliceryhl.bounces.google.com; receiver=lists.ozlabs.org) Received: from mail-ej1-x649.google.com (mail-ej1-x649.google.com [IPv6:2a00:1450:4864:20::649]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4fWFqW4B5jz2yFm for ; Thu, 12 Mar 2026 03:01:42 +1100 (AEDT) Received: by mail-ej1-x649.google.com with SMTP id a640c23a62f3a-b8ff07df5e4so1253814466b.3 for ; Wed, 11 Mar 2026 09:01:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1773244899; x=1773849699; darn=lists.ozlabs.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=FZ9wJHN98p2eqW+aluFwwdS4VIjV0bOaQ4w+79zBhNs=; b=3deXfe43m8ZrOBZt1I55Gplo9zQySbykXRXwddAUypDVVcO8jLyBcURcRLZlv3dUUz +l0cBSews7ljlNGu5u4R2de2gEgePIaWlEH7mOMykDd3NfVxy0IcxF27cnqPS4OL1YO6 pui6msGl6K0ShaF/S/OueMFppxprywXkz+nyZwlRgZroXC7JMFbT60HrLO/c8Jp5wJEt R7KZUqglruOEbP/B+8XRAfo1e76KxzCqoMwrxvgcQtUEcK1CqMdkPMcKOsiICe69oG0+ CPkEM8lCkmFLa1BfF+8XJg19mwJxPWKmHfRNMS4No8thTwdjXh6yM2IyvzraXrUlkuLZ huDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773244899; x=1773849699; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=FZ9wJHN98p2eqW+aluFwwdS4VIjV0bOaQ4w+79zBhNs=; b=i5LGhQSQw84PUB0i8b/JbhPl19myYTNBiU4KE1SLwsu69GUuCNx+vI4VKvzDMcoERg Fs5QHd6F7hKzIBT4S0JNnOT7IYyFzdUqZpgRUXg8eTaQB6WeL86nunMDagHT4aOUnBrk kb38dhCz/xF8zlDM1Ie66c3/ZTMAahP9PJ8gRGovY5TPDnDhY4DqTms6nPjKBduYIXzj ArfeentYeq59dMJMhsdoBFlDqq0NOWD0nB5XngeOV+EG9Tcv0N9DvNNfDoAuKAFao6Jm w2xvXRtaeR/sm9vjNZ5Bkfe8ok24EYZIg8FdChVNzIX+Re3QkAi/niWeYcsD9Ls5P+47 Nv9Q== X-Forwarded-Encrypted: i=1; AJvYcCUS4mpo+fRwp0j4XSmF8Td/9Nmxc4Z4RFAv0YJ3JAEGS67AczTqlAqHEk/taboMc1tPQcXcXpEExDrkuN4=@lists.ozlabs.org X-Gm-Message-State: AOJu0YxZjzmd5SESKBw8a5KR7Syfs2WFUlfEm+E72bWNcpf463qinmbj 458VVbg8IRVxR68Jjwxg/MX55vjKtQGZoLLG2mYhe0LAtcAutXu32xC9WBSQ69UT1aJIghOtYP/ hPq7kWZy2/0CNcUWvbQ== X-Received: from wrbgw30.prod.google.com ([2002:a05:6000:40de:b0:439:ac29:98cb]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a17:907:6d22:b0:b93:3792:4b03 with SMTP id a640c23a62f3a-b972e4f775amr187595066b.32.1773244898034; Wed, 11 Mar 2026 09:01:38 -0700 (PDT) Date: Wed, 11 Mar 2026 16:01:36 +0000 In-Reply-To: <20260311120418.GU1687929@ziepe.ca> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list Mime-Version: 1.0 References: <20260227200848.114019-1-david@kernel.org> <20260227200848.114019-17-david@kernel.org> <20260309142954.GM1687929@ziepe.ca> <61df6369-333c-430a-bd18-c5b1acae68ea@kernel.org> <20260311120418.GU1687929@ziepe.ca> Message-ID: Subject: Re: [PATCH v1 16/16] mm/memory: support VM_MIXEDMAP in zap_special_vma_range() From: Alice Ryhl To: Jason Gunthorpe Cc: "David Hildenbrand (Arm)" , linux-kernel@vger.kernel.org, "linux-mm @ kvack . org" , Andrew Morton , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , David Rientjes , Shakeel Butt , "Matthew Wilcox (Oracle)" , Madhavan Srinivasan , Michael Ellerman , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Jarkko Sakkinen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Greg Kroah-Hartman , "Arve =?utf-8?B?SGrDuG5uZXbDpWc=?=" , Todd Kjos , Christian Brauner , Carlos Llamas , Ian Abbott , H Hartley Sweeten , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Leon Romanovsky , Dimitri Sivanich , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Peter Zijlstra , Arnaldo Carvalho de Melo , Namhyung Kim , Andy Lutomirski , Vincenzo Frascino , Eric Dumazet , Neal Cardwell , "David S. Miller" , David Ahern , Jakub Kicinski , Paolo Abeni , Miguel Ojeda , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, linux-sgx@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-fsdevel@vger.kernel.org, netdev@vger.kernel.org, rust-for-linux@vger.kernel.org, x86@kernel.org Content-Type: text/plain; charset="utf-8" On Wed, Mar 11, 2026 at 09:04:18AM -0300, Jason Gunthorpe wrote: > On Wed, Mar 11, 2026 at 09:38:45AM +0000, Alice Ryhl wrote: > > It doesn't really make sense to have multiple binder VMAs. What happens > > with Rust Binder is that process A is receiving transactions and has the > > VMA mapped once. > > IIRC the problem is the kernel doesn't guarentee singleton VMAs, > userspace can always clone them with fork or something. Did binder > solve this somehow? The Binder VMA is DONTCOPY, so it will not be present after fork. > Since you can't assume there is only one VMA the locking becomes a > mess to cover all the cases where userspace can trigger a VMA clone. > > address space deals with this internally. > > Thus, zap_special_vma_range() is extremely hard to use. I mean, the hard part about the locking is keeping them in sync. Binder just doesn't do that. Only the original VMA gets pages inserted or zapped. If you create a second VMA, you just get a useless read-only VMA that you can't do anything with. Alice