From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 BB2193EFFDB; Tue, 19 May 2026 19:10:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779217859; cv=none; b=PBgidtvmHDQ2tAR6MWU3bWSl3WUCMlXL+rRqS7RwI4VBcEFcyBxsK5chRoS61gzPOFfqGvNpZszFoiDdpkH7sYkdH60Dz1P8KDwAiM3/6ON2FKJzVXcCXyyuD7wCwuVzxAzvrEb8B3Jcc3xfWvQIlJMH0r+4jGfYOWEg4K81Dvw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779217859; c=relaxed/simple; bh=lOS4FERTMq4vPG4lfTuFavSqzq0sytE+5bCfPQw4rKA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=HWHFxgtdBCDc5G+7YKZzMzWAfM1pIjvixhReH48+rjhyoSVzOUJ00AjMx800QiOwcg9UBnU3S8uJEXJzj6JxVY6rGGDpGnT6V2tp5qHMoesO9lWO4I2mbbGxD1E4BMTnPuqW0dGdmXjE5sHmVCNOFakV0PRGexdWFiFiwzjB5jI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EOYL5y6d; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="EOYL5y6d" 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> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260519065303.GA7918@lst.de> 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/