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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E1B6DE81BCB for ; Mon, 9 Feb 2026 14:11:00 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 51CAD10E3FE; Mon, 9 Feb 2026 14:11:00 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="N4ASDskM"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8A33A10E3FE for ; Mon, 9 Feb 2026 14:10:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1770646258; bh=XsTT1aouWN0PI0Cgpb6lDz1G8jjSfhV7436FJ8s5GG0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=N4ASDskMiPY2popv+86n5/fBaI+hHHWoWPPwXCdlbFGLIlrriRsIxHeCUwwIL/Eu2 TDLigTyyaNj1q5chJhPcwbEupmfGnVuiHtMBK5dfAcBB95+UU6ouzABSa+tYpaDoOB pHn4cpQiSyGUo0wz6B4NncABL4NvKyvi4vqAn3mxq5gfzfsqroam4YoFGBv+5H/rV0 M0L/bKN8O/aBz7+esuH69FdPVHIqBvOJ1A5GieFxfO0RIENvnPq28HOsSiC02LvdIb kNPhdwpW/+X+SRLJwjcpJou0aXcKHGDj+r/JlmFqQoOwRtfPFSeW8K7E60myI2m8g/ ACIOlbVHSgMwA== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:d919:a6e:5ea1:8a9f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id A88B117E137B; Mon, 9 Feb 2026 15:10:57 +0100 (CET) Date: Mon, 9 Feb 2026 15:10:53 +0100 From: Boris Brezillon To: Thomas Zimmermann Cc: loic.molinari@collabora.com, willy@infradead.org, frank.binns@imgtec.com, matt.coster@imgtec.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@gmail.com, simona@ffwll.ch, dri-devel@lists.freedesktop.org, linux-mm@kvack.org Subject: Re: [PATCH v3 2/6] drm/gem-shmem: Test for existence of page in mmap fault handler Message-ID: <20260209151053.397844d9@fedora> In-Reply-To: <20260209133241.238813-3-tzimmermann@suse.de> References: <20260209133241.238813-1-tzimmermann@suse.de> <20260209133241.238813-3-tzimmermann@suse.de> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Mon, 9 Feb 2026 14:27:11 +0100 Thomas Zimmermann wrote: > Not having a page pointer in the mmap fault handler is an error. Test > for this situation and return VM_FAULT_SIGBUS if so. Also replace several > lookups of the page with a local variable. > > Signed-off-by: Thomas Zimmermann Reviewed-by: Boris Brezillon > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index 5bced7db0f1f..3ee54c24e535 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -574,31 +574,31 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > struct drm_gem_object *obj = vma->vm_private_data; > + struct drm_device *dev = obj->dev; > struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); > loff_t num_pages = obj->size >> PAGE_SHIFT; > - vm_fault_t ret; > + vm_fault_t ret = VM_FAULT_SIGBUS; > struct page **pages = shmem->pages; > - pgoff_t page_offset; > + pgoff_t page_offset = vmf->pgoff - vma->vm_pgoff; /* page offset within VMA */ > + struct page *page; > unsigned long pfn; > > - /* Offset to faulty address in the VMA. */ > - page_offset = vmf->pgoff - vma->vm_pgoff; > - > dma_resv_lock(obj->resv, NULL); > > - if (page_offset >= num_pages || > - drm_WARN_ON_ONCE(obj->dev, !shmem->pages) || > - shmem->madv < 0) { > - ret = VM_FAULT_SIGBUS; > + if (page_offset >= num_pages || drm_WARN_ON_ONCE(dev, !shmem->pages) || > + shmem->madv < 0) > + goto out; > + > + page = pages[page_offset]; > + if (drm_WARN_ON_ONCE(dev, !page)) > goto out; > - } > > - if (drm_gem_shmem_try_map_pmd(vmf, vmf->address, pages[page_offset])) { > + if (drm_gem_shmem_try_map_pmd(vmf, vmf->address, page)) { > ret = VM_FAULT_NOPAGE; > goto out; > } > > - pfn = page_to_pfn(pages[page_offset]); > + pfn = page_to_pfn(page); > ret = vmf_insert_pfn(vma, vmf->address, pfn); > > out: