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 03A58C2D0CD for ; Thu, 15 May 2025 08:54:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7176B10E7C9; Thu, 15 May 2025 08:54:35 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="UtnPOeib"; dkim-atps=neutral Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by gabe.freedesktop.org (Postfix) with ESMTPS id 529FE10E7C9; Thu, 15 May 2025 08:54:34 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 6990B629ED; Thu, 15 May 2025 08:54:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 993EAC4CEE7; Thu, 15 May 2025 08:54:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747299273; bh=h+VsUgSmErOy2grzt87OXyIDJW5HdE1chW0emZWQhC4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UtnPOeib6y06l+qlV9LfdW2QLTo13UdK1gBQz/g7xaT68XnvnR/KQyA3UswXqZN8C ZlBBZ5bPPyfll8IolsEuRy+E1tPBs/yBVsyDt4ijeB7GbCNnlyiW9/RGbD4rkNO1oh qNGp5nNKLC8yR+SPyCK9gzj8pwno6kweYcBc0Ne+Yf0kwetrO3J2aMZo3WfYo3uT22 qNa/cvg9R5mpyzD4uEoAl0AkmODpatVQyXOCCNswt6HsXjQK1+cf4Cuwz6RxIMO/7z yiXh0Mgui0krxVSfYz++H+cEscRoZkf3g34tv2BzauqzgXCf5XZhBdU9w/23w+ehlN dxGHp+tDs2SbA== Date: Thu, 15 May 2025 10:54:27 +0200 From: Danilo Krummrich To: Rob Clark Cc: dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Connor Abbott , Rob Clark , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , open list Subject: Re: [PATCH v4 01/40] drm/gpuvm: Don't require obj lock in destructor path Message-ID: References: <20250514175527.42488-1-robdclark@gmail.com> <20250514175527.42488-2-robdclark@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250514175527.42488-2-robdclark@gmail.com> 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" Hi Rob, Can you please CC me on patches for GPUVM? On Wed, May 14, 2025 at 10:53:15AM -0700, Rob Clark wrote: > From: Rob Clark > > See commit a414fe3a2129 ("drm/msm/gem: Drop obj lock in > msm_gem_free_object()") for justification. Please write a proper commit message that explains the problem and the solution. Please don't just refer to another commit and leave it to the reviewer of the patch to figure this out. > Signed-off-by: Rob Clark > --- > drivers/gpu/drm/drm_gpuvm.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c > index f9eb56f24bef..1e89a98caad4 100644 > --- a/drivers/gpu/drm/drm_gpuvm.c > +++ b/drivers/gpu/drm/drm_gpuvm.c > @@ -1511,7 +1511,9 @@ drm_gpuvm_bo_destroy(struct kref *kref) > drm_gpuvm_bo_list_del(vm_bo, extobj, lock); > drm_gpuvm_bo_list_del(vm_bo, evict, lock); > > - drm_gem_gpuva_assert_lock_held(obj); > + if (kref_read(&obj->refcount) > 0) > + drm_gem_gpuva_assert_lock_held(obj); > + > list_del(&vm_bo->list.entry.gem); This seems wrong. A VM_BO object keeps a reference of the underlying GEM object, so this should never happen. This function calls drm_gem_object_put() before it returns. > > if (ops && ops->vm_bo_free) > @@ -1871,7 +1873,8 @@ drm_gpuva_unlink(struct drm_gpuva *va) > if (unlikely(!obj)) > return; > > - drm_gem_gpuva_assert_lock_held(obj); > + if (kref_read(&obj->refcount) > 0) > + drm_gem_gpuva_assert_lock_held(obj); > list_del_init(&va->gem.entry); > > va->vm_bo = NULL; > -- > 2.49.0 >