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 EE459C5DF81 for ; Mon, 24 Aug 2026 14:24:04 +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=T71NLirH3jm6znHdMrOBeJ29wllbXsTfJ6mU2Kw+zNw=; b=EGLFqNZboEDtwojMNClMmeRvh8 EJ5f9rHAyNosFIw9pke9Vz497OSLHB7bxjqTQmbRLfcyvfZs/Uw1LcYRQ1SpsPACPqurTtlXYtp3A 3HjS2SPkq7jrBijhZ6GTLS+Qpvy9NacPuuk6OeFzxhV/PmR6OE4tZT/LrMopxoaKwC6myHLxMnPC5 BANpVAVLB+oe6stJoEGNr+6cHfw5OLYLXQUkMlrmsL32sklpG+1fKitkLZLG2q15S/P8nIshRiFH6 iAA0xErwzIALI5+2D3u9Dj94g/D6VJuhNypVgVTn8IXjqZ0ztnEs6SA/JwxWZMlzQ3pZOQb4XQlff mIJ9UrHA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wyVak-0000000GlnO-2Mu5; Mon, 24 Aug 2026 14:24:02 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wyVaj-0000000Gln0-24lf for linux-nvme@bombadil.infradead.org; Mon, 24 Aug 2026 14:24:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=T71NLirH3jm6znHdMrOBeJ29wllbXsTfJ6mU2Kw+zNw=; b=rFI8iiVTimTRlQNvitqLvVDsRl F2rjwcCSzmLvzKvoutMkxwvqtUCKc1pYazQ5YpWWz7CL+Q2BzWLiyKU0HrjZGyAaU/rVDZfhhz2Px XLVTAAzjun5QRcugTD1L9MRRBo0Fa6VSZDLFcqxP6ypZAglGWKzE86HtqX9gd7dDY13+gNecRUuzc RlWSnBl3OxSXKTszNim/eeJtwbzyDTP8yyD4SLhlq6ai9mh3cmozZHAb6KlCjcNJ62eNhYBPSJWBR +4+vsPyx6UwXDOWzSUhj31ZRz0fqbmVjOkDqC4/WJqwndRA84/vYY+5I0yJ6wiNyVLk1t+DZD+iAN +9J4hZBg==; Received: from sagi by casper.infradead.org with local (Exim 4.99.1 #2 (Red Hat Linux)) id 1wyVah-00000007LQY-0Y4r; Mon, 24 Aug 2026 14:23:59 +0000 Date: Mon, 24 Aug 2026 15:23:59 +0100 From: Sagi Grimberg To: Hannes Reinecke Cc: linux-nvme@lists.infradead.org, Christoph Hellwig , Keith Busch , Chaitanya Kulkarni , Daniel Wagner , Shinichiro Kawasaki Subject: Re: [PATCH 4/6] nvme-mpath: support controller crd when failing over request Message-ID: References: <20260823084903.193188-1-sagi@grimberg.me> <20260823084903.193188-5-sagi@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 > > + /* no CRD or timer allocation failed, fallback to immediate failover */ > > + if (!fot) { > > + spin_lock_irqsave(&ns->head->requeue_lock, flags); > > + blk_steal_bios(&ns->head->requeue_list, req); > > + spin_unlock_irqrestore(&ns->head->requeue_lock, flags); > > + kblockd_schedule_work(&ns->head->requeue_work); > > + } > > Yikes. Allocation during failover is not going to make you friends. Well, it is a fairly rare event, and the fallback is exactly what we do today... > > And this whole mechanism looks pretty similar what we did over at > implementing CCR. Can you use the mechanism from there? How is this similar? It is effectively creating a container for bio_list and timer to requeue them when the timer expires...