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 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.lore.kernel.org (Postfix) with ESMTPS id 638CECD4F3C for ; Tue, 19 May 2026 19:11:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=JMCmbCNvC+HxXHksRWStC4bWizUWQNjAyE1M9dKurnI=; b=G6t5jnPAnJYso0oBuV/BBvb84u Hf9adLUH1f+62I6q2E8zDb/GnEHdhqAPfBIu7TlZNcFj3zDK8aRTp38UeTGcapTKm/E3BWArrxmB+ ybIVAZZAZmDvKoqzbU3Ai+F8yCEMNn0OJyVE/m1irFUd7extfsfzB5E97JXeUDf4qCi0N2rvZZtvq fMctngCfkNP1XA3fNRPSvlmgNhG13TWVwonxnnuRTiP7cGtmSDxcAKu/CwrzuV05JsFmziVE42uSv o1pcYtcN6TPbgQQCoyh7CdNG1TlQ2wj3yA13IH83fJRriNszs21Ah/r4C/rx2VySlMjVeiD7Exh8q FWA7Se0g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wPPqG-00000002aY5-3WXL; Tue, 19 May 2026 19:11:00 +0000 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wPPqF-00000002aXn-09nt for linux-nvme@lists.infradead.org; Tue, 19 May 2026 19:10:59 +0000 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 7F1CD60221; Tue, 19 May 2026 19:10:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3CE91F000E9; Tue, 19 May 2026 19:10:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779217858; bh=JMCmbCNvC+HxXHksRWStC4bWizUWQNjAyE1M9dKurnI=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=EOYL5y6dMjqhCVTAWrzmYzrPfz71i1htMxoZ3O7JB/WuzmFa/T/jNfYwtWzIDl3Gq hBzVN69nn/jE2ik+W7jOtsJzkwPyeIe09HnxZ+JiGJXb1HU85akKOOPwpy0w1gLOmM SpQQRkHsHMcP19ixT5yJGODy9ByFs44ruPdoEXi0PSPQ3MrVoya3jFIawIGKJ/J1w+ 2SNkqO/c3/Vx4DL9Gwl89uB+R1uR9/lbJ2jdc1FcB4lCtD8XXowFhKAP7EDfBSu/eM Un8ukWILQ5iEO36qIjpFMXS1rYY0t8WAQ/eTNvhPeVgejQj2r6BoIujvrfjzdBlpXW dmxTjtX/5Jh8w== Date: Tue, 19 May 2026 13:10:56 -0600 From: Keith Busch To: "hch@lst.de" Cc: "Achkinazi, Igor" , "sagi@grimberg.me" , "axboe@kernel.dk" , "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: Re: [PATCH] nvme-multipath: set BIO_REMAPPED on bios remapped to per-path namespace disks Message-ID: References: <20260519065303.GA7918@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260519065303.GA7918@lst.de> X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Tue, May 19, 2026 at 08:53:03AM +0200, hch@lst.de wrote: > On Mon, May 18, 2026 at 01:23:17PM -0600, Keith Busch wrote: > > > > Any reason nvme multipath can't call submit_bio_noacct_nocheck() > > directly instead? If it's safe to skip the eod check here, then it > > looks safe to skip everything else too. > > We really shouldn't expose that, and it doesn't quite to the > right checks here. > > But I think the proper fix is to stop using bio_set_dev entirely. > We do not want to associate the bio with a new blkg as those are > basically not going to exist for the underlying devices. I'm also > not sure we want to allow another round of BPF throttling either. Simply dropping the bio_set_dev usage doesn't really fix the problem here. Sure, bio_set_dev clears the BIO_REMAPPED flag, but it's not guaranteed that flag was set in the first place. I have an alternate proposal that's part of a larger series. This can notify the driver of an early error so it can decide how to deal with the bio: https://lore.kernel.org/linux-block/20260519172326.3462354-6-kbusch@meta.com/