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 720CAC43458 for ; Thu, 9 Jul 2026 06:18:45 +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=4xX18i9cZ41ZaKga0dRrI4tcTj8BTHIF2WZ/8NB4AUE=; b=k0c9VKRVfEAF5rkF+76jpUbNCr wCg1jZ2bqTk67tT9/sNoNIMXYWL9Zets3jnOzDGvhOJq1YFYacWPBfhBY1wmoCBEZL0tL4lpGV9FI GA007g56RU7skVwBoTKBXNQvX6Y1rrXYWtfsi64NSEhdHbJJHH2u6yeA/nZ30ll+2G1ac2VntGK1T oFaGitgIpjpQTC/l5W0cINRO1V/Bu7iR8sgqtXcltc6oqpS+jRWFCEgphNH7DUMYlUCzCSxvVteg+ q9egtav/e+VebCDDQfCANV84JI+DeG9vD7qPyHhQ6Qdy+z4XTufUrsEo39VtHPz5IZ5FJzygrJxvK WZYYK/3g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whi5s-000000018T0-32d2; Thu, 09 Jul 2026 06:18:44 +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 1whi5p-000000018SQ-25E2 for linux-nvme@lists.infradead.org; Thu, 09 Jul 2026 06:18:42 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id A266168BFE; Thu, 9 Jul 2026 08:18:37 +0200 (CEST) Date: Thu, 9 Jul 2026 08:18:37 +0200 From: Christoph Hellwig To: Yu Kuai Cc: Jens Axboe , Tejun Heo , Christoph Hellwig , Keith Busch , Sagi Grimberg , Alasdair Kergon , Benjamin Marzinski , Mike Snitzer , Mikulas Patocka , Dongsheng Yang , Zheng Gu , Coly Li , Kent Overstreet , Josef Bacik , Yu Kuai , Nilay Shroff , linux-block@vger.kernel.org, cgroups@vger.kernel.org, linux-nvme@lists.infradead.org, dm-devel@lists.linux.dev, linux-bcache@vger.kernel.org Subject: Re: [RFC PATCH v1 15/17] blk-cgroup: remove blkg radix tree preloading Message-ID: <20260709061837.GF16504@lst.de> References: <20260704195124.1375075-1-yukuai@kernel.org> <20260704195124.1375075-16-yukuai@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260704195124.1375075-16-yukuai@kernel.org> 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-20260708_231841_683259_42EBB164 X-CRM114-Status: GOOD ( 12.92 ) 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 Sun, Jul 05, 2026 at 03:51:22AM +0800, Yu Kuai wrote: > From: Yu Kuai > > blkg creation is now serialized by q->blkcg_mutex and no longer runs > under q->queue_lock. The radix tree is initialized with GFP_NOWAIT, so > radix_tree_insert() cannot sleep while blkcg->lock is held and the old > preload dance is no longer needed. > > Remove the preload calls and the associated unwind path. Isn't the GFP_NOWAIT a bit of a problem because it can fail way too easy? What about converting both the radix tree and list to an xarray using the internal xarray to deal with sleeping allocations?