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 44098C55160 for ; Thu, 30 Jul 2026 11:37:29 +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=ruTePSnnSCvYyFByfbakbG1f3IFNsDvcH5EG7c//Tf4=; b=lOP3Ox75jDB6kluOrU8dO0Tykx gOfe4/Wzm4YglgpkG8UjmQ2EuE1fAKrsb4SIN0gryXwmGMQhTpjNVK1QWEmc5GkHS+NgNBHWJcodB e4jLE7Xs0seoBhIH6H/NeQwRoN3VxaAPATV+/N3hv442t1LfBctvk7mrk6Ve6H7OEKmYPBeyYRQRF 1sRQxHM2d/Woe0HVxYeRnz7fAwO7Wyy985J0jQ/CSG2hQo8MGrJ5D6/w0fNoAnRwRU6IJLgOWKdv9 ibxaty2Sk2XX3ZAGzCB5PGWz2aQoqN3sLd8Xtl3sVb/WIm1CZDpFmae9czUp06efbLaq/9u6CGNmk Kge9AQlQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wpP4q-0000000AMbX-3kXS; Thu, 30 Jul 2026 11:37:28 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wpP4o-0000000AMax-1A1H for linux-nvme@lists.infradead.org; Thu, 30 Jul 2026 11:37:27 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id CEAD268C4E; Thu, 30 Jul 2026 13:37:22 +0200 (CEST) Date: Thu, 30 Jul 2026 13:37:22 +0200 From: Christoph Hellwig To: Kanchan Joshi Cc: Guixin Liu , Keith Busch , Jens Axboe , Christoph Hellwig , Sagi Grimberg , Hannes Reinecke , Nilay Shroff , Chaitanya Kulkarni , linux-nvme@lists.infradead.org Subject: Re: [PATCH 4/4] nvme: clamp FDP placement handle count to the buffer size Message-ID: <20260730113722.GD25454@lst.de> References: <20260730043105.3071328-1-kanie@linux.alibaba.com> <20260730043105.3071328-5-kanie@linux.alibaba.com> <749b4476-6d8c-4573-b51b-662b0ff57db3@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <749b4476-6d8c-4573-b51b-662b0ff57db3@samsung.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260730_043726_468653_D2918FCD X-CRM114-Status: GOOD ( 15.13 ) 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 Thu, Jul 30, 2026 at 03:10:59PM +0530, Kanchan Joshi wrote: > But I feel the need to improve (what we have) with a follow-up patch: > 1. Revise the cap, from S8_MAX - 1 to U8_MAX; since bio->bi_write_hint > is u8. Signed 8-bit -1 is indeed a really odd value, and from looking at the original commit I'm not really sure how we arrived there. > 2. And a dev_warn() to know if head->nr_plids go above the > kernel-defined cap. It's possible/fine for device to have more placement > ids, and if that happens, this can tell. Yeah.