From patchwork Mon Jan 16 11:46:33 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 9518541 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id F365B6020B for ; Mon, 16 Jan 2017 11:46:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D2E03283FF for ; Mon, 16 Jan 2017 11:46:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C7B072844A; Mon, 16 Jan 2017 11:46:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5E3CE283FF for ; Mon, 16 Jan 2017 11:46:51 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cT5kO-0007iA-QP; Mon, 16 Jan 2017 11:46:48 +0000 Received: from mx2.suse.de ([195.135.220.15]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cT5kK-0007eF-R7 for linux-arm-kernel@lists.infradead.org; Mon, 16 Jan 2017 11:46:46 +0000 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (charybdis-ext.suse.de [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 6AFA1ABDF; Mon, 16 Jan 2017 11:46:20 +0000 (UTC) From: Alexander Graf To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] arm64: Fix swiotlb fallback allocation Date: Mon, 16 Jan 2017 12:46:33 +0100 Message-Id: <1484567193-71258-1-git-send-email-agraf@suse.de> X-Mailer: git-send-email 1.8.5.6 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170116_034645_085239_5CB2C60F X-CRM114-Status: GOOD ( 11.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jisheng Zhang , Geert Uytterhoeven , Konrad Rzeszutek Wilk , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Commit b67a8b29df introduced logic to skip swiotlb allocation when all memory is DMA accessible anyway. While this is a great idea, __dma_alloc still calls swiotlb code unconditionally to allocate memory when there is no CMA memory available. The swiotlb code is called to ensure that we at least try get_free_pages(). Without initialization, swiotlb allocation code tries to access io_tlb_list which is NULL. That results in a stack trace like this: Unable to handle kernel NULL pointer dereference at virtual address 00000000 [...] [] swiotlb_tbl_map_single+0xd0/0x2b0 [] swiotlb_alloc_coherent+0x10c/0x198 [] __dma_alloc+0x68/0x1a8 [] drm_gem_cma_create+0x98/0x108 [drm] [] drm_fbdev_cma_create_with_funcs+0xbc/0x368 [drm_kms_helper] [] drm_fbdev_cma_create+0x2c/0x40 [drm_kms_helper] [] drm_fb_helper_initial_config+0x238/0x410 [drm_kms_helper] [] drm_fbdev_cma_init_with_funcs+0x98/0x160 [drm_kms_helper] [] drm_fbdev_cma_init+0x40/0x58 [drm_kms_helper] [] vc4_kms_load+0x90/0xf0 [vc4] [] vc4_drm_bind+0xec/0x168 [vc4] [...] Thankfully swiotlb code just learned how to not do allocations with the FORCE_NO option. This patch configures the swiotlb code to use that if we decide not to initialize the swiotlb framework. Fixes: b67a8b29df ("arm64: mm: only initialize swiotlb when necessary") Signed-off-by: Alexander Graf CC: Catalin Marinas CC: Jisheng Zhang CC: Geert Uytterhoeven CC: Konrad Rzeszutek Wilk --- arch/arm64/mm/init.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 716d122..380ebe7 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -404,6 +404,8 @@ void __init mem_init(void) if (swiotlb_force == SWIOTLB_FORCE || max_pfn > (arm64_dma_phys_limit >> PAGE_SHIFT)) swiotlb_init(1); + else + swiotlb_force = SWIOTLB_NO_FORCE; set_max_mapnr(pfn_to_page(max_pfn) - mem_map);