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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F308BC83F18 for ; Mon, 28 Aug 2023 10:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232339AbjH1K4e (ORCPT ); Mon, 28 Aug 2023 06:56:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49072 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232403AbjH1K4U (ORCPT ); Mon, 28 Aug 2023 06:56:20 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 440C1CFF for ; Mon, 28 Aug 2023 03:55:26 -0700 (PDT) Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:5cf4:84a1:2763:fe0d]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by madras.collabora.co.uk (Postfix) with ESMTPSA id 7620966003AF; Mon, 28 Aug 2023 11:55:21 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1693220122; bh=Y7Xrnk37ffMwXDwhIRgKCNKpNEyURXK76bZ+LzfgfJU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MPiXj4Dfk5SQk9okZJLs4FFEgbmsCH+Ofpf9s5uOSQ+2Hglnf69hWQ3QDk0kzlimG ZyABf43UGCrYR3vWBsYQJFl8oMMxcbJ4cRaUqyHAidpFv3HEcHM6qsdXJrEz92lK2e DKo+BLfmEI8k8rGRj1zyB2yO3ij0HO7xp5/PZLdtZeOEldKanV/O4dbkIPTUFEsqPr aS2mj0tOQuwG9hIIra+CJeabSiilp//N9n4emdtuEKqlG1bMv3YVV67h9n0o81i+JL awXZ15YqYk1iey6l99RiKDegI6Vtxtu43LgaD7cdR7A8oBEVIBKov1TNsaVQrWOFVw ZWAn5Z1jUZNBA== Date: Mon, 28 Aug 2023 12:55:18 +0200 From: Boris Brezillon To: Dmitry Osipenko Cc: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Christian =?UTF-8?B?S8O2bmln?= , Qiang Yu , Steven Price , Emma Anholt , Melissa Wen , Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org, intel-gfx@lists.freedesktop.org Subject: Re: [PATCH v15 02/23] drm/shmem-helper: Use flag for tracking page count bumped by get_pages_sgt() Message-ID: <20230828125518.7b926fc6@collabora.com> In-Reply-To: <20230827175449.1766701-3-dmitry.osipenko@collabora.com> References: <20230827175449.1766701-1-dmitry.osipenko@collabora.com> <20230827175449.1766701-3-dmitry.osipenko@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 27 Aug 2023 20:54:28 +0300 Dmitry Osipenko wrote: > Use separate flag for tracking page count bumped by shmem->sgt to avoid > imbalanced page counter during of drm_gem_shmem_free() time. It's fragile > to assume that populated shmem->pages at a freeing time means that the > count was bumped by drm_gem_shmem_get_pages_sgt(), using a flag removes > the ambiguity. > > Signed-off-by: Dmitry Osipenko > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 3 ++- > drivers/gpu/drm/lima/lima_gem.c | 1 + > include/drm/drm_gem_shmem_helper.h | 7 +++++++ > 3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index 78d9cf2355a5..db20b9123891 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -152,7 +152,7 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) > sg_free_table(shmem->sgt); > kfree(shmem->sgt); > } > - if (shmem->pages) > + if (shmem->got_sgt) > drm_gem_shmem_put_pages(shmem); Can't we just move this drm_gem_shmem_put_pages() call in the if (shmem->sgt) block? > > drm_WARN_ON(obj->dev, shmem->pages_use_count); > @@ -687,6 +687,7 @@ static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_ > if (ret) > goto err_free_sgt; > > + shmem->got_sgt = true; > shmem->sgt = sgt; > > return sgt; > diff --git a/drivers/gpu/drm/lima/lima_gem.c b/drivers/gpu/drm/lima/lima_gem.c > index 4f9736e5f929..28602302c281 100644 > --- a/drivers/gpu/drm/lima/lima_gem.c > +++ b/drivers/gpu/drm/lima/lima_gem.c > @@ -89,6 +89,7 @@ int lima_heap_alloc(struct lima_bo *bo, struct lima_vm *vm) > } > > *bo->base.sgt = sgt; > + bo->base.got_sgt = true; > > if (vm) { > ret = lima_vm_map_bo(vm, bo, old_size >> PAGE_SHIFT); > diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h > index ec70a98a8fe1..f87124629bb5 100644 > --- a/include/drm/drm_gem_shmem_helper.h > +++ b/include/drm/drm_gem_shmem_helper.h > @@ -73,6 +73,13 @@ struct drm_gem_shmem_object { > */ > unsigned int vmap_use_count; > > + /** > + * @got_sgt: > + * > + * True if SG table was retrieved using drm_gem_shmem_get_pages_sgt() > + */ > + bool got_sgt : 1; > + > /** > * @imported_sgt: > *