From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-io1-f53.google.com (mail-io1-f53.google.com [209.85.166.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E11762857C7 for ; Wed, 27 Aug 2025 19:55:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756324533; cv=none; b=ACwsAkBfzDogFi5mxihjov2ma1p8p9GfLVqXuw/6Gjov5ifiCF37xjUswhQiZyomvZnCgNGR0mTBsasJqcZLhG/kZ6CzaB5Tjmy53VW5QQ0+aE60J5/zKEv3tC75qE2Y5EkhPbbz5Jv+OcpTAqt1yyAnXYdCeEBVfcvvBOlLS1E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756324533; c=relaxed/simple; bh=N09Lggw+BrEhUebvMDbNZVCFYWU967lqapi7gcfd2XY=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=KAuMiDTXfy8yMlg9Vl4tgqbylpLnb1/7h3ZOFdGBT7aVbbHLRTDHNkC1fbwe6hC2Gy9JYFTGr0Sk0z028+ZFcLBctCbvnKlNa+ViGEKRZj8CzddzqH/GRMcc3RFZBXfKLoW40qMAiyLXv1jIlH4fT3kbbOMNTQIMrzPE1wsc4/U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk; spf=pass smtp.mailfrom=kernel.dk; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b=opw7qt1N; arc=none smtp.client-ip=209.85.166.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.dk Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=kernel.dk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20230601.gappssmtp.com header.i=@kernel-dk.20230601.gappssmtp.com header.b="opw7qt1N" Received: by mail-io1-f53.google.com with SMTP id ca18e2360f4ac-88432e27c77so10497739f.2 for ; Wed, 27 Aug 2025 12:55:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20230601.gappssmtp.com; s=20230601; t=1756324530; x=1756929330; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id:from :to:cc:subject:date:message-id:reply-to; bh=8MUZaQIYG6BL6uW/+MzW11iO+Nd9sV80O7ktOqXKopk=; b=opw7qt1NRQvuclajfZ9250Of9XAJs1f3vCgXtI8j10KdNTDwr4BfDVWMRtYSpEsYkP poQ6WN1s7ycRvhTaz9pakzJYcKd1Vm4Yajclrlu6FwZIwDNvktSU11iCBK1/qjCG765i zhgvKObK+wPuUr4tPBXLkmuLbPVyQvRY2SRIXPkHZBSks38uxOQ3wEX/AoYS2ItOmDGH 5IAGfQpBY/3HVXpQI/OfiG0gGb5UgCsbZGkWV0Hu2kFjE5T1SMLUIW+37VRQqEKqL+a6 qe9zotoiuYnddG7MhRQT4CepUNW+Q+Dvz0369eO74b1ZJIbdkXM96v4FSq8VT6c8ApY9 Wf2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1756324530; x=1756929330; h=content-transfer-encoding:in-reply-to:from:content-language :references:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=8MUZaQIYG6BL6uW/+MzW11iO+Nd9sV80O7ktOqXKopk=; b=SS5qvJurXscvw8GzyKrm1/fKr4hQF6gFa/S8uZvVLb18wUC/4BlVPVmyMhLFHEOejz EHMQNwUit4YAEz7sP8+4MPh/fVtpY5cWk2YtBnMEPAuMNV3+5XlVjmtnrzkVYmzuDiv3 zl7TGSxt1PCgkEJvg5gC6mwDXHMdqcDb7LVsEhFgj01RJdv/STsefJCdnU/ZVFFT1Xpm 8tVZjKaDPpJX8WWEqbAZmpowit61iR4xi27Os6lW9wzAcIqfGUxALlyPRAsPQent5U0G Px+GaohK8tgcDu7yRigyGTerVwDp8gsGbpQj7SFhjf/YMuPhw3b0gtUKcbOXD2UmK1i7 Dugw== X-Forwarded-Encrypted: i=1; AJvYcCVk6oDEWtkpV9O/JvM6Z+l4RitKm3etGVJ+vN3mRvpM3QpQKHJLSslEC6ALbwn65XmwfXnzu0b8ijVatOY=@vger.kernel.org X-Gm-Message-State: AOJu0Yztm5Lv6YJvVs2es/we5xPgrhgrq4uED5dUbJEHMtkWKylwHGzu E26wFAiT8b3MAlLRA59ewcQ0kvsw6M5O0fTgb8CmzbUL06w58mokYgYy2a8NMg8QFw8= X-Gm-Gg: ASbGncuQRqFJycSYRRMrUL5LdIQAODYDrsuoG6P4Isf+fsTEKDaw6DDflJiFWfZeOzz 5kyMh17H8TXzRmRTKQuSI9RlTzwOnobA8aRZJ94NydpdHqDOD2SAyoef3vvQd0N9e6EgfQngKjH 8SfKIiRfEiDpdPMxvEa46rX5s4CeJAllNrlKzuEpTB8e4xGpkRckNNtCqLGF6/RNLZuvlRmZXhn 542TJiWWI9SjiCulbgnMACqS2XSOzh07YIpMjV1sHR5gxmLvTCcoDhbBwn5ShQQy2PcXY+6vlp+ xGIX1IvXt1e1ZfdPo+AZ3IDcaT/mDT1uU4idqD5blx4zASc0MWcrj7FhWyAlydxE7K1/LX+GQdT COI3uPXC6iWHolT1DKtKdUCacyJQFOw== X-Google-Smtp-Source: AGHT+IEsQmmJ+nFf1MkiGe++IkZlgHN6eqs940thF8/gYFel04yO1dSdjxBZQMNe5eKew3zIP+O6Ug== X-Received: by 2002:a05:6e02:1a0f:b0:3eb:8e5a:8fd7 with SMTP id e9e14a558f8ab-3eb8e5a9145mr192453505ab.11.1756324529861; Wed, 27 Aug 2025 12:55:29 -0700 (PDT) Received: from [192.168.1.116] ([96.43.243.2]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3ea4c191550sm97846035ab.14.2025.08.27.12.55.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Aug 2025 12:55:29 -0700 (PDT) Message-ID: <1182267c-d291-47bc-8e5f-2e11aa93421b@kernel.dk> Date: Wed, 27 Aug 2025 13:55:28 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] loopback block device on top of block devices don't work anymore To: Lennart Poettering , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Rajeev Mishra References: Content-Language: en-US From: Jens Axboe In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/27/25 1:30 PM, Lennart Poettering wrote: > Heya! > > Recent kernels fail if it is attempted to create a loopback block > device on top of a block device (rather than a regular file), which is a > feature long supported on Linux kernels, and that systemd relies on > (specifically, systemd-repart does). > > For example, this used to work: > > losetup --find --show --offset=4096 --sizelimit=409600 /dev/nvme0n1 > > But now it doesn't anymore... > > This is on 6.17rc3. My educated guess is that this is caused by > Rajeev's 8aa5a3b68ad144da49a3d17f165e6561255e3529, which tightened the > screws on validating the backing file's size, which now fails if the > backing file isn't actually a file, but a block device. > > (But I didn't spend more time tracking this down.) Yeah sorry about that, the problem is the followup to the commit you mentioned, and the fix for that is here: https://web.git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git/commit/?h=block-6.17&id=d14469ed7c00314fe8957b2841bda329e4eaf4ab and will land in -rc4. -- Jens Axboe