From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx3.molgen.mpg.de (mx3.molgen.mpg.de [141.14.17.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 07C69343D84 for ; Wed, 17 Dec 2025 07:34:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=141.14.17.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956847; cv=none; b=Fon1xo+gyA28u1TQA35lEoZSvkh3xP3kQepfKr7dkmApIxUJ27KIaRPe1jpsljIfRCsL6BOmoiqn4rmrYvqHB/KRVsUupYJACCWv9BDx+X6uF2nRIi6VxNhEK9FMYJpN3m+n3JFkXj1iejQtAcnS6epaOvItG3WvU8+ckrU4Jng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765956847; c=relaxed/simple; bh=FQCskBVk7oikcFZyo9nMkmMKQOPqVZdAtWwErqXLo7A=; h=Message-ID:Date:MIME-Version:Subject:To:References:Cc:From: In-Reply-To:Content-Type; b=Le1Adw3cT/LrXmqqx4sTRVaS3xGCyEGDRUJ6EnCCcg8dQvoDmeG/4WVPh/ooxggQK2UfPeBXCaAMiV0cmGGX4EWrFOXbxS54/OnstN0/A/gUVbIGCDY5+dngYGXfToACrgnAYMS9W4hD6xsd8mOtXCkdOboqQIbBfBQkn4rG6s4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=molgen.mpg.de; spf=pass smtp.mailfrom=molgen.mpg.de; arc=none smtp.client-ip=141.14.17.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=molgen.mpg.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=molgen.mpg.de Received: from [192.168.0.192] (ip5f5af75b.dynamic.kabel-deutschland.de [95.90.247.91]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: pmenzel) by mx.molgen.mpg.de (Postfix) with ESMTPSA id 25C2161E64849; Wed, 17 Dec 2025 08:33:26 +0100 (CET) Message-ID: <7cff4b89-eeff-4048-8af3-ef9d76bdedf8@molgen.mpg.de> Date: Wed, 17 Dec 2025 08:33:24 +0100 Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Issues with md raid 1 on kernel 6.18 after booting kernel 6.19-rc1 once To: Yu Kuai References: <8fd97a33-eb5a-4c88-ac8a-bfa1dd2ced61@fnnas.com> <619a9b00-43dd-4897-8bb0-9ff29a760f52@gmail.com> Content-Language: en-US Cc: bugreports61@gmail.com, linux-raid@vger.kernel.org, linan122@huawei.com, xni@redhat.com, regressions@lists.linux.dev, Linus Torvalds From: Paul Menzel In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Dear Kuai, Am 17.12.25 um 08:17 schrieb Yu Kuai: > 在 2025/12/17 15:13, BugReports 写道: >> >> ... >> >> We'll have to backport following patch into old kernels to make >> new arrays to assemble in old kernels. .... >> >> The md array which i am talking about was not created with kernel >> 6.19, it was created sometime in 2024. >> >> It was just used in kernel 6.19 and that broke compatibility with >> my 6.18 kernel. > > I know, I mean any array that is created or assembled in new kernels > will now have lsb field stored in metadata. This field is not > defined in old kernels and that's why array can't assembled in old > kernels, due to unknown metadata. > > This is what we have to do for new features, and we're planning to > avoid the forward compatibility issue with the above patch that I > mentioned. Is there really no way around it? Just testing a new kernel and being able to go back must be supported in my opinion, at least between one or two LTS versions. Kind regards, Paul