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 6481EC83F1C for ; Sun, 27 Aug 2023 17:57:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230223AbjH0R4o (ORCPT ); Sun, 27 Aug 2023 13:56:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52100 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230028AbjH0R4X (ORCPT ); Sun, 27 Aug 2023 13:56:23 -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 526A7102 for ; Sun, 27 Aug 2023 10:56:21 -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 9F72766073A1; Sun, 27 Aug 2023 18:56:18 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1693158980; bh=VhX33TYAAg+dJ/TxzMS+7aTR0gptdB20NZJfyVWD51s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hfk3k6qXwyky5OMtU3XhLc4eAo4b9Cz+rMN5Iv1Ktx+C/wIdA3tqiNvTZ3QUS7ecD E1NBnx+ZzL/xsp+j608CQaJC7Mk/8cdwCl/9Fw/l+RvbyRmo09gTLPLYE9S19J5Vxa ss0aRcZP7qO4mSzNW4+L+zutl/Rnb0jKYyAlzL00NYRcppPM6ve4mJrEjVqcDWEMb2 OrgfmwaKI/dv/FStX6lbCg0tPB/I33uxG1yx0ojJU4TJpzVotk+H8+8uchB7Hg+aaj nFRXxUvQw8NarUtb/BqH1CDPYPWd2oJ59a4CCewhjusv3S2sII6Zy7mMGkEjgYZ3as qhpMQdGVZhr8w== 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 , Will Deacon , Peter Zijlstra , Boqun Feng , Mark Rutland Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org, intel-gfx@lists.freedesktop.org Subject: [PATCH v15 17/23] drm/shmem-helper: Add and use drm_gem_shmem_resv_assert_held() helper Date: Sun, 27 Aug 2023 20:54:43 +0300 Message-ID: <20230827175449.1766701-18-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230827175449.1766701-1-dmitry.osipenko@collabora.com> References: <20230827175449.1766701-1-dmitry.osipenko@collabora.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In a preparation of adding drm-shmem memory shrinker, move all reservation locking lockdep checks to use new drm_gem_shmem_resv_assert_held() that will resolve spurious lockdep warning about wrong locking order vs fs_reclam code paths during freeing of shmem GEM, where lockdep isn't aware that it's impossible to have locking contention with the fs_reclam at this special time. Signed-off-by: Dmitry Osipenko --- drivers/gpu/drm/drm_gem_shmem_helper.c | 37 +++++++++++++++++--------- 1 file changed, 25 insertions(+), 12 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index d96fee3d6166..ca5da976aafa 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -128,6 +128,23 @@ struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t } EXPORT_SYMBOL_GPL(drm_gem_shmem_create); +static void drm_gem_shmem_resv_assert_held(struct drm_gem_shmem_object *shmem) +{ + /* + * Destroying the object is a special case.. drm_gem_shmem_free() + * calls many things that WARN_ON if the obj lock is not held. But + * acquiring the obj lock in drm_gem_shmem_free() can cause a locking + * order inversion between reservation_ww_class_mutex and fs_reclaim. + * + * 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, we pretend it is already locked. + */ + if (kref_read(&shmem->base.refcount)) + drm_gem_shmem_resv_assert_held(shmem); +} + /** * drm_gem_shmem_free - Free resources associated with a shmem GEM object * @shmem: shmem GEM object to free @@ -142,8 +159,6 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) if (obj->import_attach) { drm_prime_gem_destroy(obj, shmem->sgt); } else if (!shmem->imported_sgt) { - dma_resv_lock(shmem->base.resv, NULL); - drm_WARN_ON(obj->dev, kref_read(&shmem->vmap_use_count)); if (shmem->sgt) { @@ -156,8 +171,6 @@ void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem) drm_gem_shmem_put_pages_locked(shmem); drm_WARN_ON(obj->dev, kref_read(&shmem->pages_use_count)); - - dma_resv_unlock(shmem->base.resv); } drm_gem_object_release(obj); @@ -170,7 +183,7 @@ static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem) struct drm_gem_object *obj = &shmem->base; struct page **pages; - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); if (kref_get_unless_zero(&shmem->pages_use_count)) return 0; @@ -228,7 +241,7 @@ static void drm_gem_shmem_kref_release_pages(struct kref *kref) */ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) { - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); kref_put(&shmem->pages_use_count, drm_gem_shmem_kref_release_pages); } @@ -252,7 +265,7 @@ static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) { int ret; - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); if (kref_get_unless_zero(&shmem->pages_pin_count)) return 0; @@ -276,7 +289,7 @@ static void drm_gem_shmem_kref_unpin_pages(struct kref *kref) static void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem) { - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); kref_put(&shmem->pages_pin_count, drm_gem_shmem_kref_unpin_pages); } @@ -357,7 +370,7 @@ int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, } else { pgprot_t prot = PAGE_KERNEL; - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); if (kref_get_unless_zero(&shmem->vmap_use_count)) { iosys_map_set_vaddr(map, shmem->vaddr); @@ -426,7 +439,7 @@ void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem, if (obj->import_attach) { dma_buf_vunmap(obj->import_attach->dmabuf, map); } else { - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); kref_put(&shmem->vmap_use_count, drm_gem_shmem_kref_vunmap); } @@ -462,7 +475,7 @@ drm_gem_shmem_create_with_handle(struct drm_file *file_priv, */ int drm_gem_shmem_madvise_locked(struct drm_gem_shmem_object *shmem, int madv) { - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); if (shmem->madv >= 0) shmem->madv = madv; @@ -478,7 +491,7 @@ void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem) struct drm_gem_object *obj = &shmem->base; struct drm_device *dev = obj->dev; - dma_resv_assert_held(shmem->base.resv); + drm_gem_shmem_resv_assert_held(shmem); drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem)); -- 2.41.0