From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F29B1606A327 for ; Sat, 14 Nov 2026 18:58:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QrNKwZwA Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 423DE10E7FA; Sat, 14 Nov 2026 18:58:38 +0000 (UTC) Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2140210E7FA; Sat, 14 Nov 2026 18:58:32 +0000 (UTC) Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 5E86760E15; Sat, 14 Nov 2026 18:58:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 705CF1F000C4; Sat, 14 Nov 2026 18:58:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794682711; bh=fbMRE2X5e/AHLMS1eoGd56ly9fU3NIj/Z6Js5YflNNw=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=QrNKwZwAQuneaTtIjhUo4EUrUSYJ0Tgqq+BeI6i3EclcZg5Aj0cKdFRA2jWkaRwVM o89/ZYvAdf+R+m4hwUnNiti7YkwNBxWtmrgYa16vUWoUKDg2kwR8Pyn2ppXAWGc1rE Odhrb3oyldEOoXHE8VirjW40E7ouLZcuaBg2Uvct+GTJGPFpgY/zNGoh4D1P7J8bcn b2LWJ3PKD+DMr0cigxJqKKOi4hps0f2zLWEdtnX4RYGDbBO2mJSQHrkOmPTL9ujpE7 VFFpA6W+fv+gE1ajgBImOn3GCzZXx606MCvodl4cErNAR6jXS0Okksz/7gb8sBZdSa 6cOWGRzdkaSmg== Date: Sat, 14 Nov 2026 18:58:21 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Andrew Morton , Willy Tarreau , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Simona Vetter , Chris Wilson , Matthew Auld , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Rik van Riel , Benjamin Herrenschmidt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linuxppc-dev@lists.ozlabs.org, stable@vger.kernel.org Subject: Re: [PATCH 2/5] drm/i915: consider vm_pgoff in vm_access() Message-ID: References: <20261112-access_shite-v1-0-988a5c470db2@kernel.org> <20261112-access_shite-v1-2-988a5c470db2@kernel.org> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261112-access_shite-v1-2-988a5c470db2@kernel.org> X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Intel-gfx" X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 12, 2026 at 11:08:58PM +0100, David Hildenbrand (Arm) wrote: > vm_access() treats the start of every VMA as the beginning of the GEM > object. After a VMA split, vm_pgoff identifies a later part of the > object. Debugger reads and writes through ptrace or /proc//mem then > access the wrong bytes. > > Properly consider vm_pgoff just like the fault handlers already do. > > Fixes: 9f909e215fea ("drm/i915: Implement vm_ops->access for gdb access into mmaps") > Cc: stable@vger.kernel.org > Signed-off-by: David Hildenbrand (Arm) And since this is an mmap-an-fd driver thing there's no need to worry about anon pgoff etc. Looks sensible to me so: Acked-by: Lorenzo Stoakes (ARM) > --- > drivers/gpu/drm/i915/gem/i915_gem_mman.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c > index 6b337684dbfe8..e3b24dc8e94f5 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c > @@ -511,13 +511,15 @@ vm_access(struct vm_area_struct *area, unsigned long addr, > struct i915_mmap_offset *mmo = area->vm_private_data; > struct drm_i915_gem_object *obj = mmo->obj; > struct i915_gem_ww_ctx ww; > + unsigned long obj_offset; > void *vaddr; > int err = 0; > > if (i915_gem_object_is_readonly(obj) && write) > return -EACCES; > > - addr -= area->vm_start; > + obj_offset = area->vm_pgoff - drm_vma_node_start(&mmo->vma_node); > + addr += (obj_offset << PAGE_SHIFT) - area->vm_start; > if (range_overflows_t(u64, addr, len, obj->base.size)) > return -EINVAL; > > > -- > 2.43.0 > -- Cheers, Lorenzo