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 X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4193BC282DA for ; Wed, 17 Apr 2019 20:48:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12B4521773 for ; Wed, 17 Apr 2019 20:48:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732989AbfDQUsW (ORCPT ); Wed, 17 Apr 2019 16:48:22 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:47984 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727013AbfDQUsW (ORCPT ); Wed, 17 Apr 2019 16:48:22 -0400 Received: from mail-it1-f197.google.com ([209.85.166.197]) by youngberry.canonical.com with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1hGrTg-0000OP-BW for linux-kernel@vger.kernel.org; Wed, 17 Apr 2019 20:48:20 +0000 Received: by mail-it1-f197.google.com with SMTP id o197so73941ito.3 for ; Wed, 17 Apr 2019 13:48:20 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition:user-agent; bh=FKs6b6RLzOW6Pz03ZnepEKUCxUG5lBr2ZKHFqCP8uyY=; b=ewuInX+FOw1AIuaS50Wc1sYSNkK/+EsWmTtMoS7PmzNtgK+0u4gtuVgRBziAvyTYMi TSFQYOm/be8CuKwdI2JtAYZPP6AE9jbgYSwDn3SVkdK0Q4k5lzJ3tSF1IoKZCFtZ+OiM APOVypppoRjSb7Tu+4TpeJ7puyq2DYsLCrpb9prWShPqvew1Ri7GCHa5Kw8/zAFrTtaR EdtdrDKIFSb+RNl6bPQEn1TPdYDVPPHaL6wrDPDDPCoye7w+OmfNyt/8q/SdqOc+KQH7 5mybXg2EIbiw2c0o0Az5DjI+U5ZaNWJY7EtQBEOmu/KAyW5TiaCrAlsaC3TD7hD6XuWy 4wDA== X-Gm-Message-State: APjAAAX5m9eUAlznqsGAXtwZxLQTK3Ftkc9ITBnLXsph/qDHmCHHnI8d DJIs218l80rWHUHH56NpNRBFjiSDFdVLQI5g06foC0AS6jcsupEb8kdaY25d12JjkxVALF9p5B4 nn/v8dCiWvG8oRv/ecGmrH+0OPxw2WmEwPVrqMul5ww== X-Received: by 2002:a05:6638:60e:: with SMTP id g14mr35030884jar.62.1555534099336; Wed, 17 Apr 2019 13:48:19 -0700 (PDT) X-Google-Smtp-Source: APXvYqxhLv8FzWKOUKRcFaZQ9Q3wrgT5tWJRdwXvjRnIIBQ9dn0sCLbXg/33/O5gcbPcDwLcpplrVg== X-Received: by 2002:a05:6638:60e:: with SMTP id g14mr35030865jar.62.1555534099071; Wed, 17 Apr 2019 13:48:19 -0700 (PDT) Received: from xps13.canonical.com (c-71-56-235-36.hsd1.co.comcast.net. [71.56.235.36]) by smtp.gmail.com with ESMTPSA id c99sm47406itd.4.2019.04.17.13.48.17 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 17 Apr 2019 13:48:18 -0700 (PDT) Date: Wed, 17 Apr 2019 14:48:17 -0600 From: dann frazier To: Christoph Hellwig Cc: Marek Szyprowski , Robin Murphy , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Xinwei Kong Subject: [RFC] arm64: swiotlb: cma_alloc error spew Message-ID: <20190417204817.GA28897@xps13.dannf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org hey, I'm seeing an issue on a couple of arm64 systems[*] where they spew ~10K "cma: cma_alloc: alloc failed" messages at boot. The errors are non-fatal, and bumping up cma to a large enough size (~128M) gets rid of them - but that seems suboptimal. Bisection shows that this started after commit fafadcd16595 ("swiotlb: don't dip into swiotlb pool for coherent allocations"). It looks like __dma_direct_alloc_pages() is opportunistically using CMA memory but falls back to non-CMA if CMA disabled or unavailable. I've demonstrated that this fallback is indeed returning a valid pointer. So perhaps the issue is really just the warning emission. The following naive patch solves the problem for me - just silence the cma errors, since it looks like a soft error. But is there a better approach? [*] APM X-Gene & HiSilicon Hi1620 w/ SMMU disabled diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 6310ad01f915b..0324aa606c173 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c @@ -112,7 +112,7 @@ struct page *__dma_direct_alloc_pages(struct device *dev, size_t size, /* CMA can be used only in the context which permits sleeping */ if (gfpflags_allow_blocking(gfp)) { page = dma_alloc_from_contiguous(dev, count, page_order, - gfp & __GFP_NOWARN); + true); if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { dma_release_from_contiguous(dev, page, count); page = NULL;