From nobody Thu Feb 12 06:32:08 2026 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 55113EEAA7A for ; Thu, 14 Sep 2023 23:29:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231263AbjINX3l (ORCPT ); Thu, 14 Sep 2023 19:29:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48942 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230412AbjINX3Z (ORCPT ); Thu, 14 Sep 2023 19:29:25 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5EEEE271E for ; Thu, 14 Sep 2023 16:29:16 -0700 (PDT) Received: from workpc.. (109-252-153-31.dynamic.spd-mgts.ru [109.252.153.31]) (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: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id 03814660736A; Fri, 15 Sep 2023 00:29:13 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1694734155; bh=AJfzXqUuOYq/YDCQsWCWT/OFILNeW+U2Pu7qFD8Rn7I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bYsnFvCSoJdnB1sQ5AHNHoF9SF+NkuVcL3ObKLbyd39R20SBhLLImZyGjbrPqHP0D gsdyfIZ0WYvH7zrCYPe2G34ozAngjZig0asn/qVfn7xjLn4J//0UcL+BdJymVlibh9 rAceDCcSs8ROfoz1KzHrDRhYPkZwa3doq+3YEkmHzAzgiOw587OYaoqCir44jOXs+1 AHNRGwZpIjssbrXWvXrmRrsxcOiKm6e0shaN+Pxf918KUs9f0W4wDgLhH+oydc/VbR aoz8gxaBDMyky4sSqjQtMXZ7u+6JA6MrKir1Im5GcZlnyVXzjCMiRVffbFSVf5eLYT 8HkdP2qp/My+A== From: Dmitry Osipenko To: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , =?UTF-8?q?Christian=20K=C3=B6nig?= , Qiang Yu , Steven Price , Boris Brezillon , Emma Anholt , Melissa Wen Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org Subject: [PATCH v17 12/18] drm/shmem-helper: Prepare drm_gem_shmem_free() to shrinker addition Date: Fri, 15 Sep 2023 02:27:15 +0300 Message-ID: <20230914232721.408581-13-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230914232721.408581-1-dmitry.osipenko@collabora.com> References: <20230914232721.408581-1-dmitry.osipenko@collabora.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Prepare drm_gem_shmem_free() to addition of memory shrinker support to drm-shmem by adding and using variant of put_pages() that doesn't touch reservation lock. Reservation shouldn't be touched because lockdep will trigger a bogus warning about locking contention with fs_reclaim code paths that can't happen during the time when GEM is freed and lockdep doesn't know about that. Signed-off-by: Dmitry Osipenko --- drivers/gpu/drm/drm_gem_shmem_helper.c | 55 +++++++++++++++++--------- 1 file changed, 37 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_g= em_shmem_helper.c index 8a8eab4d0332..4959f51b647a 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -128,6 +128,41 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(stru= ct drm_device *dev, size_t } EXPORT_SYMBOL_GPL(drm_gem_shmem_create); =20 +static void +__drm_gem_shmem_release_pages(struct drm_gem_shmem_object *shmem) +{ + struct drm_gem_object *obj =3D &shmem->base; + +#ifdef CONFIG_X86 + if (shmem->map_wc) + set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT); +#endif + + drm_gem_put_pages(obj, shmem->pages, + shmem->pages_mark_dirty_on_put, + shmem->pages_mark_accessed_on_put); + shmem->pages =3D NULL; +} + +static void +__drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem) +{ + /* + * Destroying the object is a special case. Acquiring the obj + * lock in drm_gem_shmem_put_pages_locked() can cause a locking + * order inversion between reservation_ww_class_mutex and fs_reclaim + * when called from drm_gem_shmem_free(). + * + * This deadlock is not actually possible, because no one should + * be already holding the lock when drm_gem_shmem_free() is called. + * Unfortunately lockdep is not aware of this detail. So when the + * refcount drops to zero, make sure that the reservation lock + * isn't touched here. + */ + if (refcount_dec_and_test(&shmem->pages_use_count)) + __drm_gem_shmem_release_pages(shmem); +} + /** * drm_gem_shmem_free - Free resources associated with a shmem GEM object * @shmem: shmem GEM object to free @@ -142,8 +177,6 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *sh= mem) if (obj->import_attach) { drm_prime_gem_destroy(obj, shmem->sgt); } else { - dma_resv_lock(shmem->base.resv, NULL); - drm_WARN_ON(obj->dev, refcount_read(&shmem->vmap_use_count)); =20 if (shmem->sgt) { @@ -153,11 +186,9 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *s= hmem) kfree(shmem->sgt); } if (shmem->pages) - drm_gem_shmem_put_pages_locked(shmem); + __drm_gem_shmem_put_pages(shmem); =20 drm_WARN_ON(obj->dev, refcount_read(&shmem->pages_use_count)); - - dma_resv_unlock(shmem->base.resv); } =20 drm_gem_object_release(obj); @@ -207,21 +238,9 @@ static int drm_gem_shmem_get_pages_locked(struct drm_g= em_shmem_object *shmem) */ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) { - struct drm_gem_object *obj =3D &shmem->base; - dma_resv_assert_held(shmem->base.resv); =20 - if (refcount_dec_and_test(&shmem->pages_use_count)) { -#ifdef CONFIG_X86 - if (shmem->map_wc) - set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT); -#endif - - drm_gem_put_pages(obj, shmem->pages, - shmem->pages_mark_dirty_on_put, - shmem->pages_mark_accessed_on_put); - shmem->pages =3D NULL; - } + __drm_gem_shmem_put_pages(shmem); } EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); =20 --=20 2.41.0