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 6D471C761A6 for ; Mon, 3 Apr 2023 14:38:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233709AbjDCOia (ORCPT ); Mon, 3 Apr 2023 10:38:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49772 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233657AbjDCOi2 (ORCPT ); Mon, 3 Apr 2023 10:38:28 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB8EC5279 for ; Mon, 3 Apr 2023 07:38:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 469B761EB3 for ; Mon, 3 Apr 2023 14:38:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5ACF8C433EF; Mon, 3 Apr 2023 14:38:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680532706; bh=V9f23WxeNQlrK7fZEVquO+gAzb4iRSIuZZBjY4E2Jt0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fj7dqId8gAJswQXDxKUkH22tzl2jl+VzCV8vM2e37d1+CHbmnStYJj0oDIPiDhz4t 89ShFOU7vwTylNV5jOUQGlIKxM297nqp7HA7+jxwEaDoxxhymh8sv/JTKpiodp/LzA skNIAVq9L31FF9Unx42Qgb7+OGGPXldZH6X6BHYM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Belanger , Felix Kuehling , Alex Deucher , Sasha Levin Subject: [PATCH 6.1 055/181] drm/amdkfd: Fixed kfd_process cleanup on module exit. Date: Mon, 3 Apr 2023 16:08:10 +0200 Message-Id: <20230403140416.942062100@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140415.090615502@linuxfoundation.org> References: <20230403140415.090615502@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: David Belanger [ Upstream commit 20bc9f76b6a2455c6b54b91ae7634f147f64987f ] Handle case when module is unloaded (kfd_exit) before a process space (mm_struct) is released. v2: Fixed potential race conditions by removing all kfd_process from the process table first, then working on releasing the resources. v3: Fixed loop element access / synchronization. Fixed extra empty lines. Signed-off-by: David Belanger Reviewed-by: Felix Kuehling Signed-off-by: Alex Deucher Signed-off-by: Sasha Levin --- drivers/gpu/drm/amd/amdkfd/kfd_module.c | 1 + drivers/gpu/drm/amd/amdkfd/kfd_priv.h | 1 + drivers/gpu/drm/amd/amdkfd/kfd_process.c | 67 +++++++++++++++++++++--- 3 files changed, 62 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_module.c b/drivers/gpu/drm/amd/amdkfd/kfd_module.c index 09b966dc37681..aee2212e52f69 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_module.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_module.c @@ -77,6 +77,7 @@ static int kfd_init(void) static void kfd_exit(void) { + kfd_cleanup_processes(); kfd_debugfs_fini(); kfd_process_destroy_wq(); kfd_procfs_shutdown(); diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h index bf610e3b683bb..6d6588b9beed7 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h +++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h @@ -928,6 +928,7 @@ bool kfd_dev_is_large_bar(struct kfd_dev *dev); int kfd_process_create_wq(void); void kfd_process_destroy_wq(void); +void kfd_cleanup_processes(void); struct kfd_process *kfd_create_process(struct file *filep); struct kfd_process *kfd_get_process(const struct task_struct *task); struct kfd_process *kfd_lookup_process_by_pasid(u32 pasid); diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c index dd351105c1bcf..7f68d51541e8e 100644 --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c @@ -1167,6 +1167,17 @@ static void kfd_process_free_notifier(struct mmu_notifier *mn) kfd_unref_process(container_of(mn, struct kfd_process, mmu_notifier)); } +static void kfd_process_notifier_release_internal(struct kfd_process *p) +{ + cancel_delayed_work_sync(&p->eviction_work); + cancel_delayed_work_sync(&p->restore_work); + + /* Indicate to other users that MM is no longer valid */ + p->mm = NULL; + + mmu_notifier_put(&p->mmu_notifier); +} + static void kfd_process_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm) { @@ -1181,17 +1192,22 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn, return; mutex_lock(&kfd_processes_mutex); + /* + * Do early return if table is empty. + * + * This could potentially happen if this function is called concurrently + * by mmu_notifier and by kfd_cleanup_pocesses. + * + */ + if (hash_empty(kfd_processes_table)) { + mutex_unlock(&kfd_processes_mutex); + return; + } hash_del_rcu(&p->kfd_processes); mutex_unlock(&kfd_processes_mutex); synchronize_srcu(&kfd_processes_srcu); - cancel_delayed_work_sync(&p->eviction_work); - cancel_delayed_work_sync(&p->restore_work); - - /* Indicate to other users that MM is no longer valid */ - p->mm = NULL; - - mmu_notifier_put(&p->mmu_notifier); + kfd_process_notifier_release_internal(p); } static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = { @@ -1200,6 +1216,43 @@ static const struct mmu_notifier_ops kfd_process_mmu_notifier_ops = { .free_notifier = kfd_process_free_notifier, }; +/* + * This code handles the case when driver is being unloaded before all + * mm_struct are released. We need to safely free the kfd_process and + * avoid race conditions with mmu_notifier that might try to free them. + * + */ +void kfd_cleanup_processes(void) +{ + struct kfd_process *p; + struct hlist_node *p_temp; + unsigned int temp; + HLIST_HEAD(cleanup_list); + + /* + * Move all remaining kfd_process from the process table to a + * temp list for processing. Once done, callback from mmu_notifier + * release will not see the kfd_process in the table and do early return, + * avoiding double free issues. + */ + mutex_lock(&kfd_processes_mutex); + hash_for_each_safe(kfd_processes_table, temp, p_temp, p, kfd_processes) { + hash_del_rcu(&p->kfd_processes); + synchronize_srcu(&kfd_processes_srcu); + hlist_add_head(&p->kfd_processes, &cleanup_list); + } + mutex_unlock(&kfd_processes_mutex); + + hlist_for_each_entry_safe(p, p_temp, &cleanup_list, kfd_processes) + kfd_process_notifier_release_internal(p); + + /* + * Ensures that all outstanding free_notifier get called, triggering + * the release of the kfd_process struct. + */ + mmu_notifier_synchronize(); +} + static int kfd_process_init_cwsr_apu(struct kfd_process *p, struct file *filep) { unsigned long offset; -- 2.39.2