From patchwork Tue Apr 25 11:43:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wander Lairson Costa X-Patchwork-Id: 8632 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp3344514vqo; Tue, 25 Apr 2023 04:50:28 -0700 (PDT) X-Google-Smtp-Source: AKy350baAg2Xn5pVHBlZ0Ol4mlVq4neaI03LsgzbAT2hRo0bRr4JWVE2H5tb3rmzrHCx3LEa3Ve3 X-Received: by 2002:a17:90a:134b:b0:24b:8221:5bb4 with SMTP id y11-20020a17090a134b00b0024b82215bb4mr12028963pjf.4.1682423428039; Tue, 25 Apr 2023 04:50:28 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1682423428; cv=none; d=google.com; s=arc-20160816; b=J8pRn+fPLT/Nyhf6baL2ubqJjUC5kX565DKw9tqbblWYcRGgSUbmscxVASiZVkcoce tni0gPflnSaUZydrI1JYbfechQqGaG8YD6wMOLWp7i4yDV0B7tG2ZY4GSALX86nexi60 KhlDeVJ+D3/H3Ej+7jxdQ5uTTgHWdzxyQmNR0Spztkb0feh/oJGhbvcxSc0Z2750XruX kJojXlGPLGjKV4yN5KOYu7x/hwBkUJAjSswCwYE3izJ+6Kw9Oh9GiTZZ4exgkYsHKmwb YYhMF0+EhFPWhVjTwJTZ4pUzllksBgvhl3KlalIJy/g9QTyAp/hupdB27FzA/mYo88fk J2Ag== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:to:from:dkim-signature; bh=UaWpsXpa/AF5G4pTpImmB8IVb55RNgXy+3d4orrYfrY=; b=U38k44/0ZFzfkH2jyq+T0SGHVZsECv+rZLPZRqSYutSLVMd3YTbOA1PsCGvS3hR59b vMuGNdPzo7irTJR710JmdhNQF8nFQ2lcuhO+F2v/kX3a0sRKfmcbYWg2875ktmCoUSYU r5lQdpqi7+6RzWLuXA+DU5zDiCxM2xQUduXzNFLp51Q9Xp4g9ltmmkJqdq8tbBfAfxKv yGKI81QuWhisRa6dfnDgLKjzcRiPIOzW09dyVMMIkdKNRrFfqTz23EqmVmjMVTs/jmBt vfs2c1JRta8hjT7Gg2JQ5et/eL773KP/R+V84x0n7ORhzlMATKH7rA1N1Wlh9VNhdmCO ysPQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=fvxhwhKl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id i12-20020a17090adc0c00b002474560207csi13099825pjv.189.2023.04.25.04.50.13; Tue, 25 Apr 2023 04:50:28 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=fvxhwhKl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233853AbjDYLo1 (ORCPT + 99 others); Tue, 25 Apr 2023 07:44:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45196 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232851AbjDYLoY (ORCPT ); Tue, 25 Apr 2023 07:44:24 -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 317604236 for ; Tue, 25 Apr 2023 04:43:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1682423019; 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=UaWpsXpa/AF5G4pTpImmB8IVb55RNgXy+3d4orrYfrY=; b=fvxhwhKlf25sjClxMDN5Wl8wa69jYUjjD8lZ4mnKOuZjh8dbK9s8sFqXDAhTP55JQAg/bH NAk/aLRnbxKcsYW1+XTK0qDLUgRhIJWEw3qSXW1slNmEG83a07LzamrD2H4/ZaWXg6iK7W eJRZLGX7WNnlmQUmh69eY6nd6G5d1B0= 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-447-Oq304pwpOIezhthgFGV7-A-1; Tue, 25 Apr 2023 07:43:33 -0400 X-MC-Unique: Oq304pwpOIezhthgFGV7-A-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 01E0D101A531; Tue, 25 Apr 2023 11:43:32 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.32.181]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B225C15BA0; Tue, 25 Apr 2023 11:43:24 +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 , Huacai Chen , Geert Uytterhoeven , Oleg Nesterov , Kefeng Wang , Andrew Morton , "Liam R. Howlett" , Christian Brauner , Kees Cook , Andrei Vagin , Shakeel Butt , linux-kernel@vger.kernel.org (open list), linux-perf-users@vger.kernel.org (open list:PERFORMANCE EVENTS SUBSYSTEM) Subject: [PATCH v7 0/3] Introduce put_task_struct_atomic_sleep() Date: Tue, 25 Apr 2023 08:43:00 -0300 Message-Id: <20230425114307.36889-1-wander@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.8 X-Spam-Status: No, score=-2.3 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1764148828226492211?= X-GMAIL-MSGID: =?utf-8?q?1764148828226492211?= 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. One practical example is a splat inside inactive_task_timer(), which is called in a interrupt context: CPU: 1 PID: 2848 Comm: life Kdump: loaded Tainted: G W --------- Hardware name: HP ProLiant DL388p Gen8, BIOS P70 07/15/2012 Call Trace: dump_stack_lvl+0x57/0x7d mark_lock_irq.cold+0x33/0xba ? stack_trace_save+0x4b/0x70 ? save_trace+0x55/0x150 mark_lock+0x1e7/0x400 mark_usage+0x11d/0x140 __lock_acquire+0x30d/0x930 lock_acquire.part.0+0x9c/0x210 ? refill_obj_stock+0x3d/0x3a0 ? rcu_read_lock_sched_held+0x3f/0x70 ? trace_lock_acquire+0x38/0x140 ? lock_acquire+0x30/0x80 ? refill_obj_stock+0x3d/0x3a0 rt_spin_lock+0x27/0xe0 ? refill_obj_stock+0x3d/0x3a0 refill_obj_stock+0x3d/0x3a0 ? inactive_task_timer+0x1ad/0x340 kmem_cache_free+0x357/0x560 inactive_task_timer+0x1ad/0x340 ? switched_from_dl+0x2d0/0x2d0 __run_hrtimer+0x8a/0x1a0 __hrtimer_run_queues+0x91/0x130 hrtimer_interrupt+0x10f/0x220 __sysvec_apic_timer_interrupt+0x7b/0xd0 sysvec_apic_timer_interrupt+0x4f/0xd0 ? asm_sysvec_apic_timer_interrupt+0xa/0x20 asm_sysvec_apic_timer_interrupt+0x12/0x20 RIP: 0033:0x7fff196bf6f5 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. v7: * Fix typos. * Add an explanation why the new function doesn't conflict with delayed_free_task(). 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() with the atomic safe version include/linux/sched/task.h | 49 ++++++++++++++++++++++++++++++++++++++ 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, 78 insertions(+), 21 deletions(-) Reviewed-by: Valentin Schneider Acked-by: Waiman Long