From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794682711; b=UBpKyFgaO+Y5FrnEqmPaZ4t7DhsHDZyU8XuZbpPpdV83KDkpLwy3RNyfGeMb4qFmTc9F ZZxpt/A0q0N/CXr9zT7rI/yBPdu3vpProVozUjl8o6VpDa+24NHIr/PsSnA2R9XX5BG6K TZ1y8BW00MDBkZp3xSIziFEvhdrbQmKJmzIiYDo1H0oVVfjYNTWKwCbpTZcOmMtfke2hw zE9AbPXD9QomGIkEmnw+xhsDr2ncJchqyXeuGSJxu0HpEOOzXVVnTEcpTNWFvT5Mqa2nq CZQ1Lx+ovXBQN3CeskD/KVQLHUv6KEXVFocReyXQ4YLuyZELp5yLl7fDJ928Icutz7w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794682711; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=fbMRE2X5e/AHLMS1eoGd56ly9fU3NIj/Z6Js5YflNNw=; b=3GrOt6v73UYy8RA5FnEb07L6lsrkwcEJ4ktEUsAcILjxZgicM6RLkbp3bR3uyd/syrD/ c1+5DSO3TJauTkzMLVE+ySu6VunhgohbdNvBDhjmPa+6OVzzSMxWuztDqv4LMmG6c1FO7 yYaX8UzchRRela1KwlCwNV0ZdKsAJhwptj89yLQBGJR2qrpGk/GNPqPL/wT769J6EZFXO ZsMSgb4ikK+i+7mDroNevy3+5PkoWwVX+zc0AvJqb9bFxFol6DsJKkoAJo+v1i5PmImGQ /cTtouF7IgdB6wcbf3vI0amXgom8zDu80uo/4pi5WITfscd9EdPUUjBwtsY83v6CH5Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=QrNKwZwA; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 782B0606A32E; Sat, 14 Nov 2026 18:58:31 +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: 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-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list 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> 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