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 4F3C8C77B72 for ; Fri, 14 Apr 2023 12:56:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229799AbjDNM4t (ORCPT ); Fri, 14 Apr 2023 08:56:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40056 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229689AbjDNM4s (ORCPT ); Fri, 14 Apr 2023 08:56:48 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6ED93AD24 for ; Fri, 14 Apr 2023 05:55:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681476951; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=T997QlX8ulRak2Xfd7UnKYdetFcqQN7kWdIRh6IkroE=; b=Le59vJFeScCLIQ5si5heeVOuSrBFGJc+NUwT9CV6DEjyuUrGE2gQ6tABMRMjDRxfdBdZAl Y+2TyVdW1ZouL9VYqxKkShC7GfCEN9fKZnrwD0fmo45at7luXQZQUjrx19mA8mLW1oHYCI JcDKHzGRD0ClZ2f+7YGw2z9Fs/+zE8U= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-423-WmKRPv8DMrCu00hGWtGdsw-1; Fri, 14 Apr 2023 08:55:49 -0400 X-MC-Unique: WmKRPv8DMrCu00hGWtGdsw-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id ECF8D88F479; Fri, 14 Apr 2023 12:55:45 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.9.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1793406AA66; Fri, 14 Apr 2023 12:55:37 +0000 (UTC) From: Wander Lairson Costa To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , Will Deacon , Waiman Long , Boqun Feng , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , "Eric W. Biederman" , Wander Lairson Costa , Andrew Morton , Guo Ren , Kefeng Wang , Oleg Nesterov , "Liam R. Howlett" , Vlastimil Babka , Christian Brauner , Andrei Vagin , Shakeel Butt , linux-kernel@vger.kernel.org (open list), linux-perf-users@vger.kernel.org (open list:PERFORMANCE EVENTS SUBSYSTEM) Subject: [PATCH v6 0/3] Introduce put_task_struct_atomic_sleep() Date: Fri, 14 Apr 2023 09:55:26 -0300 Message-Id: <20230414125532.14958-1-wander@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-perf-users@vger.kernel.org The put_task_struct() function reduces a usage counter and invokes __put_task_struct() when the counter reaches zero. In the case of __put_task_struct(), it indirectly acquires a spinlock, which operates as a sleeping lock under the PREEMPT_RT configuration. As a result, invoking put_task_struct() within an atomic context is not feasible for real-time (RT) kernels. To address this issue, this patch series introduces a new function called put_task_struct_atomic_safe(). When compiled with the PREEMPT_RT configuration, this function defers the call to __put_task_struct() to a process context. Additionally, the patch series rectifies known problematic call sites to ensure smooth functioning. Changelog ========= v1: * Initial implementation fixing the splat. v2: * Isolate the logic in its own function. * Fix two more cases caught in review. v3: * Change __put_task_struct() to handle the issue internally. v4: * Explain why call_rcu() is safe to call from interrupt context. v5: * Explain why __put_task_struct() doesn't conflict with put_task_sruct_rcu_user. v6: * As per Sebastian's review, revert back the implementation of v2 with a distinct function. * Add a check in put_task_struct() to warning when called from a non-sleepable context. * Address more call sites. Wander Lairson Costa (3): sched/core: warn on call put_task_struct in invalid context sched/task: Add the put_task_struct_atomic_safe() function treewide: replace put_task_struct() witht the atomic safe version include/linux/sched/task.h | 45 ++++++++++++++++++++++++++++++++++++++ kernel/events/core.c | 6 ++--- kernel/fork.c | 8 +++++++ kernel/locking/rtmutex.c | 10 ++++----- kernel/sched/core.c | 6 ++--- kernel/sched/deadline.c | 16 +++++++------- kernel/sched/rt.c | 4 ++-- 7 files changed, 74 insertions(+), 21 deletions(-) -- 2.39.2