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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5BE2CC19F2D for ; Thu, 11 Aug 2022 07:27:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D94678E0003; Thu, 11 Aug 2022 03:27:31 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D45D18E0001; Thu, 11 Aug 2022 03:27:31 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C340A8E0003; Thu, 11 Aug 2022 03:27:31 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B4C578E0001 for ; Thu, 11 Aug 2022 03:27:31 -0400 (EDT) Received: from smtpin16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7DE84C0729 for ; Thu, 11 Aug 2022 07:27:31 +0000 (UTC) X-FDA: 79786481502.16.E757818 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf26.hostedemail.com (Postfix) with ESMTP id D6C1F14005F for ; Thu, 11 Aug 2022 07:27:30 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 0105468AA6; Thu, 11 Aug 2022 09:27:26 +0200 (CEST) Date: Thu, 11 Aug 2022 09:27:26 +0200 From: Christoph Hellwig To: Michal Hocko Cc: Christoph Hellwig , Andrew Morton , Baoquan He , John Donnelly , David Hildenbrand , linux-mm@kvack.org, LKML Subject: Re: [PATCH] dma/pool: do not complain if DMA pool is not allocated Message-ID: <20220811072726.GA13886@lst.de> References: <20220325122559.14251-1-mhocko@kernel.org> <20220325164856.GA16800@lst.de> 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) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1660202851; a=rsa-sha256; cv=none; b=2RlAehy1NSbQzLMZUIXIfb3kkEwcJvwwhKoTr/r5IMpyTFF46j14HD0Kzx/6WAnH8DstuX xERwTkqQjKMt42SLuxpK+raDCR3PTmbv87b2g6ivC5y26OBCCLImfM6oai1mgVeEsG5xuq sjCyEYJnYpAW+bbWM53xjHYb9yAuRPk= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=none; spf=none (imf26.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1660202851; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5NI4rtPwfNreczjiXER6PzliSmJdH5R3XzR0jms11Ek=; b=ZelZxXeTmNZftjKt1C7FPLPHnT8r1VZPrmIk7HpZWKmI+BUZoxIOAr52Vy1OCX8JPkSHYk ZgLCcDfPsBuHuxM1nYlJu3qz2nzQAlgaqmYjcFMWs3lVqPy52sa6xvSft28tCXsSiFXCmZ rdDulzIdJgAb5IrQoNQ7upc3Aeenr70= X-Rspamd-Queue-Id: D6C1F14005F Authentication-Results: imf26.hostedemail.com; dkim=none; spf=none (imf26.hostedemail.com: domain of hch@lst.de has no SPF policy when checking 213.95.11.211) smtp.mailfrom=hch@lst.de; dmarc=none X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: b7rupibb4hosez99jjc4sbsrgf9eidc9 X-HE-Tag: 1660202850-406112 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Mar 25, 2022 at 05:54:32PM +0100, Michal Hocko wrote: > > > I thought there are only few pages in the managed by the DMA zone. This > > > is still theoretically possible so I think __GFP_NOWARN makes sense here > > > but it would require to change the patch description. > > > > > > Is this really worth it? > > > > In general I think for kernels where we need the pool and can't allocate > > it, a warning is very useful. We just shouldn't spew it when there is > > no need for the pool to start with. > > Well, do we have any way to find that out during early boot? In general an architecture / configuration that selects CONFIG_ZONE_DMA needs it. We could try to reduce that dependency and/or make it boot time configurable, but there's still plenty of device with sub-32bit addessing limits around, so I'm not sure it would help much.