From nobody Sun Sep 14 16:23:33 2025 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 859CBC25B4E for ; Fri, 20 Jan 2023 15:04:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231280AbjATPE3 (ORCPT ); Fri, 20 Jan 2023 10:04:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38504 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230024AbjATPEW (ORCPT ); Fri, 20 Jan 2023 10:04:22 -0500 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 47F0D7CCC1 for ; Fri, 20 Jan 2023 07:03:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674227013; 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: in-reply-to:in-reply-to:references:references; bh=6iRsFgdyFm9aCh9hJwwja26lzouAKLjx2fwTp+CTHC4=; b=NeBGpfJuLOkvMoRl6iRI/RQzWMebyjXrhuvP/kniEbjccQ0kxvmIiEPg5Van3hOi73TXky r74zGYPbgeIbjTC6Oq0sYQjJ9DtLtGg4nOXVvrKB36mbQ/yQRzU6U+ghvUeBVVeJmhElgN WJLn1hZL1rYbn7qflw1SbAbP40s6nsU= 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-133-0x9ArX0hPPaHNE5UgIfsEQ-1; Fri, 20 Jan 2023 10:03:26 -0500 X-MC-Unique: 0x9ArX0hPPaHNE5UgIfsEQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id ACE998588E7; Fri, 20 Jan 2023 15:03:25 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.32.187]) by smtp.corp.redhat.com (Postfix) with ESMTP id A5AA8492B03; Fri, 20 Jan 2023 15:03:20 +0000 (UTC) From: Wander Lairson Costa To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Valentin Schneider , "Eric W. Biederman" , Geert Uytterhoeven , Andrew Morton , Catalin Marinas , Kefeng Wang , Wander Lairson Costa , Oleg Nesterov , Thomas Gleixner , Sebastian Andrzej Siewior , Andy Lutomirski , "Liam R. Howlett" , Fenghua Yu , Andrei Vagin , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v2 2/4] sched/deadline: fix inactive_task_timer splat Date: Fri, 20 Jan 2023 12:02:40 -0300 Message-Id: <20230120150246.20797-3-wander@redhat.com> In-Reply-To: <20230120150246.20797-1-wander@redhat.com> References: <20230120150246.20797-1-wander@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" inactive_task_timer() executes in interrupt (atomic) context. It calls put_task_struct(), which indirectly acquires sleeping locks under PREEMPT_RT. Below is an example of a splat that happened in a test environment: 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 Use put_task_struct_atomic_safe() instead. Signed-off-by: Wander Lairson Costa Cc: Thomas Gleixner --- kernel/sched/deadline.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 0d97d54276cc..03400c61a994 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1442,7 +1442,7 @@ static enum hrtimer_restart inactive_task_timer(struc= t hrtimer *timer) dl_se->dl_non_contending =3D 0; unlock: task_rq_unlock(rq, p, &rf); - put_task_struct(p); + put_task_struct_atomic_safe(p); =20 return HRTIMER_NORESTART; } --=20 2.39.0