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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE795C43217 for ; Sat, 19 Feb 2022 00:52:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240496AbiBSAxF (ORCPT ); Fri, 18 Feb 2022 19:53:05 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:57196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239657AbiBSAxF (ORCPT ); Fri, 18 Feb 2022 19:53:05 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 8934C27791A for ; Fri, 18 Feb 2022 16:52:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645231965; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc; bh=BuTnFWUhBBRMiJESbdOS+zm0fZMoAD6VWeIUETzvR9Q=; b=cEUASDxBCp2cvXMRNkHNhAx1fBxs0IeBD3D6wH9JTiWBoO2Iq5B3dAXZUJ5ovAO779BEIP xTi4A4Cw02S7y5o0uQRpiijsQ1uNT4RIDHREi4kbGM1YdoAjqGoCawc9ffNHsfvbcoQN03 mVPFWeGjxJH54MJXHcyhGLtsJ5NU8I4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-672-de9sK9NhMqaxxLEalV_5JQ-1; Fri, 18 Feb 2022 19:52:42 -0500 X-MC-Unique: de9sK9NhMqaxxLEalV_5JQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C908A2F45; Sat, 19 Feb 2022 00:52:38 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-39.pek2.redhat.com [10.72.12.39]) by smtp.corp.redhat.com (Postfix) with ESMTP id A173C62D4E; Sat, 19 Feb 2022 00:52:22 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hch@lst.de, cl@linux.com, 42.hyeyoo@gmail.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, vbabka@suse.cz, David.Laight@ACULAB.COM, david@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net, linux-crypto@vger.kernel.org, steffen.klassert@secunet.com, netdev@vger.kernel.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, linux-s390@vger.kernel.org, michael@walle.cc, linux-i2c@vger.kernel.org, wsa@kernel.org Subject: [PATCH 00/22] Don't use kmalloc() with GFP_DMA Date: Sat, 19 Feb 2022 08:51:59 +0800 Message-Id: <20220219005221.634-1-bhe@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org Let's replace it with other ways. This is the first step towards removing dma-kmalloc support in kernel (Means that if everyting is going well, we can't use kmalloc(GFP_DMA) to allocate buffer in the future). This series includes below changes which are easier to recognise and make. 1) Remove GFP_DMA from dma_alloc_wc/noncoherent(), dma_pool_alloc(), and dmam_alloc_coherent() which are redundant to specify GFP_DMA when calling. 2) Replace kmalloc(GFP_DMA)/dma_map_xxxx() pair with dma_alloc_noncoherent(). Next, plan to investigate how we should handle places as below. We firstly need figure out whether they really need buffer from ZONE_DMA. If yes, how to change them with other ways. This need help from maintainers, experts from sub-components and code contributors or anyone knowing them well. E.g s390 and crypyto, we need guidance and help. 1) Kmalloc(GFP_DMA) in s390 platform, under arch/s390 and drivers/s390; 2) Kmalloc(GFP_DMA) in drivers/crypto; 3) Kmalloc(GFP_DMA) in network drivers under drivers/net, e.g skb buffer requested from DMA zone. 4) Kmalloc(GFP_DMA) in device register control, e.g using regmap, devres to read/write register, while memory from ZONE_DMA is required, e.g i2c, spi. For this first patch series, thanks to Hyeonggon for helping reviewing and great suggestions on patch improving. We will work together to continue the next steps of work. Any comment, thought, or suggestoin is welcome and appreciated, including but not limited to: 1) whether we should remove dma-kmalloc support in kernel(); 3) why kmalloc(GFP_DMA) is needed in a certain place. why memory from ZONE_DMA has to be requested in the case. 2) how to replace it with other ways in any place which you are familiar with; ===========================Background information======================= Prelusion: Earlier, allocation failure was observed when calling kmalloc() with GFP_DMA. It requests to allocate slab page from DMA zone while no managed pages at all in there. Because in the current kernel, dma-kmalloc will be created as long as CONFIG_ZONE_DMA is enabled. However, kdump kernel of x86_64 doesn't have managed pages on DMA zone since below commit. The details of this kdump issue can be found in reference link (a). commit 6f599d84231f ("x86/kdump: Always reserve the low 1M when the crashkernel option is specified") To make clear the root cause and fix, many reviewers contributed their thoughts and suggestions in the thread of the patchset v3 (a). Finally Hyeonggon concluded what we can do to fix the kdump issue for now as a workaround, and further action to get rid of dma-kmalloc which is not a reasonable existence. (Please see Hyeonggon's reply in refernce (b)). Quote Hyeonggon's words here: ~~~~ What about one of those?: 1) Do not call warn_alloc in page allocator if will always fail to allocate ZONE_DMA pages. 2) let's check all callers of kmalloc with GFP_DMA if they really need GFP_DMA flag and replace those by DMA API or just remove GFP_DMA from kmalloc() 3) Drop support for allocating DMA memory from slab allocator (as Christoph Hellwig said) and convert them to use DMA32 and see what happens ~~~~ Then Christoph acked Hyeonggon's conclusion, and said "This is the right thing to do, but it will take a while." (See reference link (c)) ==========Reference links======= (a) v4 post including the details of kdump issue: https://lore.kernel.org/all/20211223094435.248523-1-bhe@redhat.com/T/#u (b) v3 post including many reviewers' comments: https://lore.kernel.org/all/20211213122712.23805-1-bhe@redhat.com/T/#u (c) Hyeonggon's mail concluding the solution: https://lore.kernel.org/all/20211215044818.GB1097530@odroid/T/#u (d) Christoph acked the plan in this mail: https://lore.kernel.org/all/20211215072710.GA3010@lst.de/T/#u Baoquan He (21): parisc: pci-dma: remove stale code and comment gpu: ipu-v3: Don't use GFP_DMA when calling dma_alloc_coherent() drm/sti: Don't use GFP_DMA when calling dma_alloc_wc() sound: n64: Don't use GFP_DMA when calling dma_alloc_coherent() fbdev: da8xx: Don't use GFP_DMA when calling dma_alloc_coherent() fbdev: mx3fb: Don't use GFP_DMA when calling dma_alloc_wc() usb: gadget: lpc32xx_udc: Don't use GFP_DMA when calling dma_alloc_coherent() usb: cdns3: Don't use GFP_DMA when calling dma_alloc_coherent() uio: pruss: Don't use GFP_DMA when calling dma_alloc_coherent() staging: emxx_udc: Don't use GFP_DMA when calling dma_alloc_coherent() staging: emxx_udc: Don't use GFP_DMA when calling dma_alloc_coherent() spi: atmel: Don't use GFP_DMA when calling dma_alloc_coherent() spi: spi-ti-qspi: Don't use GFP_DMA when calling dma_alloc_coherent() usb: cdns3: Don't use GFP_DMA when calling dma_pool_alloc() usb: udc: lpc32xx: Don't use GFP_DMA when calling dma_pool_alloc() net: marvell: prestera: Don't use GFP_DMA when calling dma_pool_alloc() net: ethernet: mtk-star-emac: Don't use GFP_DMA when calling dmam_alloc_coherent() ethernet: rocker: Use dma_alloc_noncoherent() for dma buffer HID: intel-ish-hid: Use dma_alloc_noncoherent() for dma buffer mmc: wbsd: Use dma_alloc_noncoherent() for dma buffer mtd: rawnand: Use dma_alloc_noncoherent() for dma buffer Hyeonggon Yoo (1): net: moxa: Don't use GFP_DMA when calling dma_alloc_coherent() arch/parisc/kernel/pci-dma.c | 8 --- drivers/gpu/drm/sti/sti_cursor.c | 4 +- drivers/gpu/drm/sti/sti_hqvdp.c | 2 +- drivers/gpu/ipu-v3/ipu-image-convert.c | 2 +- drivers/hid/intel-ish-hid/ishtp-fw-loader.c | 23 +++----- drivers/mmc/host/wbsd.c | 45 +++----------- drivers/mtd/nand/raw/marvell_nand.c | 55 ++++++++++------- .../ethernet/marvell/prestera/prestera_rxtx.c | 2 +- drivers/net/ethernet/mediatek/mtk_star_emac.c | 2 +- drivers/net/ethernet/moxa/moxart_ether.c | 4 +- drivers/net/ethernet/rocker/rocker_main.c | 59 ++++++++----------- drivers/spi/spi-atmel.c | 4 +- drivers/spi/spi-ti-qspi.c | 2 +- drivers/staging/emxx_udc/emxx_udc.c | 2 +- drivers/staging/media/imx/imx-media-utils.c | 2 +- drivers/uio/uio_pruss.c | 2 +- drivers/usb/cdns3/cdns3-gadget.c | 4 +- drivers/usb/gadget/udc/lpc32xx_udc.c | 4 +- drivers/video/fbdev/da8xx-fb.c | 4 +- drivers/video/fbdev/fsl-diu-fb.c | 2 +- drivers/video/fbdev/mx3fb.c | 2 +- sound/mips/snd-n64.c | 2 +- 22 files changed, 97 insertions(+), 139 deletions(-) -- 2.17.2