From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755509AbbAFOvX (ORCPT ); Tue, 6 Jan 2015 09:51:23 -0500 Received: from 8bytes.org ([81.169.241.247]:37847 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755421AbbAFOvT (ORCPT ); Tue, 6 Jan 2015 09:51:19 -0500 From: Joerg Roedel To: Ingo Molnar , Thomas Gleixner , "H. Peter Anvin" , Konrad Rzeszutek Wilk Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Joerg Roedel , Joerg Roedel Subject: [PATCH 2/3] x86, swiotlb: Try coherent allocations with __GFP_NOWARN Date: Tue, 6 Jan 2015 15:51:13 +0100 Message-Id: <1420555874-11506-3-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1420555874-11506-1-git-send-email-joro@8bytes.org> References: <1420555874-11506-1-git-send-email-joro@8bytes.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joerg Roedel When we boot a kdump kernel in high memory, there is by default only 72MB of low memory available. The swiotlb code takes 64MB of it (by default) so that there are only 8MB left to allocate from. On systems with many devices this causes page allocator warnings from dma_generic_alloc_coherent(): systemd-udevd: page allocation failure: order:0, mode:0x280d4 CPU: 0 PID: 197 Comm: systemd-udevd Tainted: G W 3.12.28-4-default #1 Hardware name: HP ProLiant DL980 G7, BIOS P66 07/30/2012 ffff8800781335e0 ffffffff8150b1db 00000000000280d4 ffffffff8113af90 0000000000000000 0000000000000000 ffff88007efdbb00 0000000100000000 0000000000000000 0000000000000000 0000000000000000 0000000000000001 Call Trace: [] dump_trace+0x7d/0x2d0 [] show_stack_log_lvl+0x94/0x170 [] show_stack+0x21/0x50 [] dump_stack+0x41/0x51 [] warn_alloc_failed+0xf0/0x160 [] __alloc_pages_slowpath+0x72f/0x796 [] __alloc_pages_nodemask+0x1ea/0x210 [] dma_generic_alloc_coherent+0x96/0x140 [] x86_swiotlb_alloc_coherent+0x1c/0x50 [] ttm_dma_pool_alloc_new_pages+0xab/0x320 [ttm] [] ttm_dma_populate+0x3ce/0x640 [ttm] [] ttm_tt_bind+0x36/0x60 [ttm] [] ttm_bo_handle_move_mem+0x55f/0x5c0 [ttm] [] ttm_bo_move_buffer+0x105/0x130 [ttm] [] ttm_bo_validate+0xc1/0x130 [ttm] [] ttm_bo_init+0x24b/0x400 [ttm] [] radeon_bo_create+0x16c/0x200 [radeon] [] radeon_ring_init+0x11e/0x2b0 [radeon] [] r100_cp_init+0x123/0x5b0 [radeon] [] r100_startup+0x194/0x230 [radeon] [] r100_init+0x223/0x410 [radeon] [] radeon_device_init+0x6af/0x830 [radeon] [] radeon_driver_load_kms+0x89/0x180 [radeon] [] drm_get_pci_dev+0x121/0x2f0 [drm] [ocal_pci_probe+0x39/0x60 [] pci_device_probe+0xa9/0x120 [] driver_probe_device+0x9d/0x3d0 [] __driver_attach+0x8b/0x90 [] bus_for_each_dev+0x5b/0x90 [] bus_add_driver+0x1f8/0x2c0 [] driver_register+0x5b/0xe0 [] do_one_initcall+0xf2/0x1a0 [] load_module+0x1207/0x1c70 [] SYSC_finit_module+0x75/0xa0 [] system_call_fastpath+0x16/0x1b [<00007fac533d2789>] 0x7fac533d2788 After these warnings the code enters a fall-back path and allocated directly from the swiotlb aperture in the end. So remove these warnings as this is not a fatal error. Signed-off-by: Joerg Roedel --- arch/x86/kernel/pci-swiotlb.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c index 77dd0ad..79b2291 100644 --- a/arch/x86/kernel/pci-swiotlb.c +++ b/arch/x86/kernel/pci-swiotlb.c @@ -20,6 +20,14 @@ void *x86_swiotlb_alloc_coherent(struct device *hwdev, size_t size, { void *vaddr; + /* + * When booting a kdump kernel in high memory these allocations are very + * likely to fail, as there are by default only 8MB of low memory to + * allocate from. So disable the warnings from the allocator when this + * happens. SWIOTLB also implements fall-backs for failed allocations. + */ + flags |= __GFP_NOWARN; + vaddr = dma_generic_alloc_coherent(hwdev, size, dma_handle, flags, attrs); if (vaddr) -- 1.9.1