From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi1-f200.google.com (mail-oi1-f200.google.com [209.85.167.200]) by kanga.kvack.org (Postfix) with ESMTP id F280E6B7EB0 for ; Fri, 7 Dec 2018 16:19:30 -0500 (EST) Received: by mail-oi1-f200.google.com with SMTP id p131so2480437oia.21 for ; Fri, 07 Dec 2018 13:19:30 -0800 (PST) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id h64si1865551oif.143.2018.12.07.13.19.29 for ; Fri, 07 Dec 2018 13:19:30 -0800 (PST) Subject: Re: [PATCH v3 4/9] drm/rockchip/rockchip_drm_gem.c: Convert to use vm_insert_range References: <20181206184227.GA28656@jordon-HP-15-Notebook-PC> From: Robin Murphy Message-ID: Date: Fri, 7 Dec 2018 21:19:24 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Souptick Joarder Cc: Andrew Morton , Matthew Wilcox , Michal Hocko , hjc@rock-chips.com, Heiko Stuebner , airlied@linux.ie, Linux-MM , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org On 2018-12-07 8:30 pm, Souptick Joarder wrote: > On Fri, Dec 7, 2018 at 8:20 PM Robin Murphy wrote: >> >> On 06/12/2018 18:42, Souptick Joarder wrote: >>> Convert to use vm_insert_range() to map range of kernel >>> memory to user vma. >>> >>> Signed-off-by: Souptick Joarder >>> Tested-by: Heiko Stuebner >>> Acked-by: Heiko Stuebner >>> --- >>> drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 20 ++------------------ >>> 1 file changed, 2 insertions(+), 18 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> index a8db758..2cb83bb 100644 >>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> @@ -221,26 +221,10 @@ static int rockchip_drm_gem_object_mmap_iommu(struct drm_gem_object *obj, >>> struct vm_area_struct *vma) >>> { >>> struct rockchip_gem_object *rk_obj = to_rockchip_obj(obj); >>> - unsigned int i, count = obj->size >> PAGE_SHIFT; >>> unsigned long user_count = vma_pages(vma); >>> - unsigned long uaddr = vma->vm_start; >>> - unsigned long offset = vma->vm_pgoff; >>> - unsigned long end = user_count + offset; >>> - int ret; >>> - >>> - if (user_count == 0) >>> - return -ENXIO; >>> - if (end > count) >>> - return -ENXIO; >>> >>> - for (i = offset; i < end; i++) { >>> - ret = vm_insert_page(vma, uaddr, rk_obj->pages[i]); >>> - if (ret) >>> - return ret; >>> - uaddr += PAGE_SIZE; >>> - } >>> - >>> - return 0; >>> + return vm_insert_range(vma, vma->vm_start, rk_obj->pages, >>> + user_count); >> >> We're losing vm_pgoff handling here, which given the implication in >> 57de50af162b, may well be a regression for at least some combination of >> GPU and userspace driver (I assume that commit was in the context of >> some version of the Arm Mali driver, possibly on RK3288). > > In commit 57de50af162b, vma->vm_pgoff = 0 for GEM mmap handler context > and removing it from common path which means if call stack looks like > rockchip_gem_mmap_buf() -> rockchip_drm_gem_object_mmap() -> > rockchip_drm_gem_object_mmap_iommu(), then we might have a non zero > vma->vm_pgoff context which is not handled. > > This is the problem you are pointing ? right ? Exactly - if unconditionally zeroing the offset in the PRIME mmap() path was a problem, then the implication is that there are callers of that path who expect the offset to be honoured here. Robin.