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.gnu.org (lists.gnu.org [209.51.188.17]) (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 B9EC0D11183 for ; Thu, 27 Nov 2025 11:35:54 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vOaHU-0004Ri-2X; Thu, 27 Nov 2025 06:35:24 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vOaHS-0004RI-98 for qemu-devel@nongnu.org; Thu, 27 Nov 2025 06:35:22 -0500 Received: from mail-pf1-x429.google.com ([2607:f8b0:4864:20::429]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1vOaHQ-00028k-Qd for qemu-devel@nongnu.org; Thu, 27 Nov 2025 06:35:22 -0500 Received: by mail-pf1-x429.google.com with SMTP id d2e1a72fcca58-7a9cdf62d31so975475b3a.3 for ; Thu, 27 Nov 2025 03:35:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1764243317; x=1764848117; darn=nongnu.org; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=nRuf9e9htrjlcoWjm82qmYj7ZbkH7/9T0fHo1lzijoQ=; b=ip2L3KZMs40cQ6+y0mvwna5XOtQ6J+76h+QkpI7LqT8/NFkaLeibQcGQSljoNGLoHj vAhZ/OEpzAjMTpfONAd/8ibNYo1Kfh1IxtVx5tnbuGQ3HhWM5LqdqLy2mQ05/tSEvp2f BQPdPuCyossPSSKfFae7QC691CErNHmdqwYnOZDN/uNvpgsk8P0exwGIV/FD+mUEfiD9 34zeD6XBIFXxtM9nchV7EWoqjkRsM2FDgt+o9PnE+4R8utBuirX8SoZFR9MqSmncu+Ox v3VQbcY5ijDeENuh94+Y3TwNRcA7ywUyOBsiAohHqc0x6rmiqzqiwZV9wf3swg9vuSGs 2QQQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1764243317; x=1764848117; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=nRuf9e9htrjlcoWjm82qmYj7ZbkH7/9T0fHo1lzijoQ=; b=cLn3TYXGKI8/QVRNpbxi4xZjRgZ7ddnmpGnXAgweCzdV5LuEHgMZeeMk/X0r0Ac5f/ DnlOsOyDlnp9UP5h21jgArVaZE1nZjexMUVybD0KIT2sOfOKEvRjy6F6CgR97lPoqSE9 la/DKEKUylmwwbJL9h01O93vyqIGVnZfd0yE1d1MU4FkZ7BztRgXMMpZa7tKolD9HzlU JaXtVQQHyE54ZzWvHRE1tDXS6rUnY1JdU7crSPPoMo8C99RmioCI6D3SXaTs0BfSn7Sr H39GOx+iQUs47ox11j0eSAcOTrl84/t6xO/KHGdv67AkxdjQVixvAYaf7akOVPDBhwWY bjkg== X-Gm-Message-State: AOJu0YyLgQlpKNvgXgp3IOqCFfhct2UyV3xjPPfVOJYCDfbGWuJ3tQfi dAKOlx/OZ3vHBMJ1qYwLzNVOnSLKF+kDQOhxakLjGWeL61VkzTf2LgsxOye1tihQ+4RVc4bHzI4 Gndx8v3jb5nxsreVZ8nm2Yr9ASOgc5g8= X-Gm-Gg: ASbGnctKcsnfELvqIxe3WlykvDW4T9iaAcjX5He2yCl+lJk9/7YSlej6Wr0NYhTSwkd 0X9Mml0+u0AsqTDa7/meVdGq9ALHRkHkzwzEQpv86jPw1bU49ffNz2jWYr6MpR6SE3mxo4uowJS z57i4ppOprmsMbvkNb63riHf86qJUnJ9zWlcWtl0No2S+xEvGpH3isH/gHamExsIzm1Vm/QR7Z5 NxEPLJ5BWQyIoOhDLPrBnTwGY0hO9lvYH2PKJKss6DV8EGvNnv0fHXuUlAw2U55C2NFcQ== X-Google-Smtp-Source: AGHT+IEuU5IR7wgy6jCNXIg1Hn7J8V/bAIXc8BLAARXvH4oqZlZG3ue8gQWAkqDhPBu6175WvJ67d05YznMhXdrsQF0= X-Received: by 2002:a05:7022:b881:b0:11b:a8e3:8468 with SMTP id a92af1059eb24-11c9d861131mr13038689c88.33.1764243317178; Thu, 27 Nov 2025 03:35:17 -0800 (PST) MIME-Version: 1.0 References: <20251126154734.940066-1-pzmarzly0@gmail.com> In-Reply-To: From: =?UTF-8?B?UGF3ZcWCIFptYXJ6xYJ5?= Date: Thu, 27 Nov 2025 11:35:06 +0000 X-Gm-Features: AWmQ_blbvIVxuevPv2ADMrwCJMATwF3PCrp0HqD12ggWL7m_Yloz0vByq12FNy0 Message-ID: Subject: Re: [PATCH] migration: Fix writing mapped_ram + ignore_shared snapshots To: Peter Xu Cc: qemu-devel@nongnu.org, farosas@suse.de Content-Type: text/plain; charset="UTF-8" Received-SPF: pass client-ip=2607:f8b0:4864:20::429; envelope-from=pzmarzly0@gmail.com; helo=mail-pf1-x429.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, 26 Nov 2025 at 21:42, Peter Xu wrote: > Now I start to question whether I should have that other fix of yours to be > for this release or next. > > If this use case is completely broken, we shouldn't need to rush -rc > window, now I plan to merge all these fixes later when 11.0 dev window > opens. Let me know if you, or Fabiano, has any comments. It is broken if you set ignore-shared and actually have any shared block, but what could work today is if you just toggle the ignore-shared flag on without setting up any shared blocks. In that case, writing will work fine, but reading will crash. That's how I stumbled upon this rabbithole in the first place: I forgot to unset the flag and was surprised by parsing error. Whether it is worth fixing now - I don't know, setting ignore-shared when there are no shared blocks doesn't really make sense, so most likely nobody does it on purpose. In either case, I need to stop working on this for now, I thought this will be a tiny side project that'll help me get my first patches in (and get used to collaborating over email), but now it's growing in complexity and I have other things that I need to prioritize. Hopefully I'll come back to this within 11.x window. Thanks for all the help so far, Peter, Fabiano!