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 BB07ECD4F54 for ; Tue, 19 May 2026 06:53:18 +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=q9aV0Ct8j8x+VbvsXPKmm/pmXIO0lpmi8IIp1arRQRw=; b=yanu5f+8DnxVld/AeNE26OuetJ xSeKiLhTUu5oSGo/Bt5XKnz55QT6srwYLGQD/0mXH5NbI4W5fyxOEN2oP6EEuLv2aJ7HTW/ZXeNMh mHTbjCKV9dzQ7W7AjJ9AV7/on5tS8J0F8KqhrpACkioWA1Mnbx7gjsWkPiaTZKvUeMwFvmMtbP8e+ YwUbbs8txl7rKh0jUxjmI2mM/ZjqFH01ekTD/SCmnnJ+AgAsH3663/2UAR3rsXj88tNA963vhHwhg MFQ5MknrjjP68mfxyDdcOAUSAhLpfVsq4AtD4RmJJEYjNCoxHVnnEOqHQkjU5rkSPxFMhAbnQ/5qP 06fFZ4Jw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wPEKK-00000000PlJ-0syV; Tue, 19 May 2026 06:53:16 +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 1wPEKH-00000000Pjo-2At9 for linux-nvme@lists.infradead.org; Tue, 19 May 2026 06:53:15 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id EE7C668CFE; Tue, 19 May 2026 08:53:03 +0200 (CEST) Date: Tue, 19 May 2026 08:53:03 +0200 From: "hch@lst.de" To: Keith Busch Cc: "Achkinazi, Igor" , "hch@lst.de" , "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: <20260519065303.GA7918@lst.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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-20260518_235313_700731_C70DC7F3 X-CRM114-Status: GOOD ( 17.36 ) 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 Mon, May 18, 2026 at 01:23:17PM -0600, Keith Busch wrote: > On Mon, May 18, 2026 at 02:52:56PM +0000, Achkinazi, Igor wrote: > > @@ -511,6 +511,13 @@ static void nvme_ns_head_submit_bio(struct bio *bio) > > ns = nvme_find_path(head); > > if (likely(ns)) { > > bio_set_dev(bio, ns->disk->part0); > > + /* > > + * Mark the bio as remapped to the per-path namespace disk so > > + * that bio_check_eod() is skipped on resubmission (e.g. from > > + * bio splitting in blk_mq_submit_bio). The EOD check already > > + * passed on the multipath head disk. > > + */ > > + bio_set_flag(bio, BIO_REMAPPED); > > 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.