From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 AB8322BE031; Fri, 6 Feb 2026 06:43:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770360199; cv=none; b=mckTTQajLBrIsCEX+GNt2/+6GcNH/FR8+p1B+cmQFRKclveHkldTNDF8FDZnGY2YZOhF+1H4vIUpKI2g0nGue5xxdV0LuhP9iVotfVSm41/qvlBOEIy7x6JUszGEL3TQX7ZkKsq9GWPpnGufEd/JhPbm9XPPU1X2VCZZ451TcZA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770360199; c=relaxed/simple; bh=pKtN8WnCuYXwkWzFvsMQJ/HMrJxyfv9Zg9vpPy/V71o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hGZOmQFCV6sBzQDvZt0166hjGPHt+UkLqkUyYqMlR53+BxFWQVjz1FLzAvR0PME3RsxK7vpV1QWAe9JJG9J7hp3+AY1sVNelUWTf/JsUdJZi2OvhlrR5WQGUHxM2Mm7q8lhB5293HihghnZnNgBM307qZjpFsgRYFZetfhrLeVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=SEBPOHA6; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="SEBPOHA6" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=ZXrRBnmDZKOWe4vfrMf+XXsjZ5+XXZ/4HO8NGf3/PuQ=; b=SEBPOHA6XebvRYRnQLAZyfY3O0 zPgcE8UITkCIrubNX3UJsMfaL1pPelcPlLCKLo73ZVN96QqfN32iy1MC5ZYXF958Yj9Q2old4HIEi 1TV4YE/P9Tj1n/qGlBghMeCbH7JWGBsgv2IPuo0QtPJI0cWFDHprPwz0f8c9vMMg8jSdST8HM6Qij odQZ2OXIY6KN3lFGy/VVAIZX7e1mPRDKx58DaMQdO70CEs+ex3K4cv3608i5BBvMVFLwftdYFXtOV UTRR2I9un++/dXClFjqA+/EZ1/+lFRp4PynD9G0emzYtnTJUr9AZ8AQPaoA16Pgl7IvLsTBazwBg6 LjifVnwg==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1voFYk-0000000AxLL-49gg; Fri, 06 Feb 2026 06:43:19 +0000 Date: Thu, 5 Feb 2026 22:43:18 -0800 From: Christoph Hellwig To: Christoph =?iso-8859-1?Q?B=F6hmwalder?= Cc: Jens Axboe , drbd-dev@lists.linbit.com, linux-kernel@vger.kernel.org, Lars Ellenberg , Philipp Reisner , linux-block@vger.kernel.org Subject: Re: [PATCH] drbd: always set BLK_FEAT_STABLE_WRITES Message-ID: References: <20260205173928.3166880-2-christoph.boehmwalder@linbit.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260205173928.3166880-2-christoph.boehmwalder@linbit.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Thu, Feb 05, 2026 at 06:39:29PM +0100, Christoph Böhmwalder wrote: > DRBD requires stable pages because it may read the same bio data > multiple times for local disk I/O and network transmission, and in > some cases for calculating checksums. > > The BLK_FEAT_STABLE_WRITES flag is set when the device is first > created, but blk_set_stacking_limits() clears it whenever a > backing device is attached. In some cases the flag may be > inherited from the backing device, but we want it to be enabled > at all times. This looks like a bug. If an underlying device requires BLK_FEAT_STABLE_WRITES, the upper device needs to inherit it. > Note: this commit is based on the for-6.19/block tree in case it is > still possible to take it into the 6.19 release as this *could* lead > to silent data corruption. However, due to other protection > mechanisms in DRBD, this is relatively unlikely to happen in the > real world and we have not seen any corresponding reports from users. > So if this only lands in 6.20/7.0, it is also fine. I'm fine with this as a hot fix for 6.19 and -stable: Reviewed-by: Christoph Hellwig But can you please also do the proper block layer fix and then revert the drbd one?