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 469E0C4332F for ; Mon, 13 Dec 2021 12:40:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236855AbhLMMkT (ORCPT ); Mon, 13 Dec 2021 07:40:19 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:30690 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236851AbhLMMkS (ORCPT ); Mon, 13 Dec 2021 07:40:18 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1639399217; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=NK/4X4SVplBV/d2WQkR15TolXv79Z6sovnlVcWNu2ko=; b=TgofbcQxzHgy2M2xZX1krjOO7biUbPAYwMDQpF46pnQDCpDQl95geYR/v/39siVtcd0pZr l2Jh8wlUwmcUhUGI92c2wOfN4sluv02bl+FnMjuJ/WVSIrwDxq3z3k6E5dlmT8alVWA2HV B2zN9+wtiUZlQXSxHjIMHadldaqn9zE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-23-PWbM3UJBOQmjqn3I9y3CUw-1; Mon, 13 Dec 2021 07:40:14 -0500 X-MC-Unique: PWbM3UJBOQmjqn3I9y3CUw-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3F33593925; Mon, 13 Dec 2021 12:40:13 +0000 (UTC) Received: from wcosta.com (ovpn-116-142.gru2.redhat.com [10.97.116.142]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3B79779D2; Mon, 13 Dec 2021 12:40:03 +0000 (UTC) From: Wander Lairson Costa To: linux-kernel@vger.kernel.org Cc: Steven Rostedt , Thomas Gleixner , Sebastian Andrzej Siewior , linux-rt-users@vger.kernel.org, Wander Lairson Costa Subject: [PATCH v2 2/2] blktrace: switch trace spinlock to a raw spinlock Date: Mon, 13 Dec 2021 09:37:37 -0300 Message-Id: <20211213123737.9147-3-wander@redhat.com> In-Reply-To: <20211213123737.9147-1-wander@redhat.com> References: <20211213123737.9147-1-wander@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org TRACE_EVENT disables preemption before calling the callback. Because of that blktrace triggers the following bug under PREEMPT_RT: BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:35 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 119, name: kworker/u2:2 5 locks held by kworker/u2:2/119: #0: ffff8c2e4a88f538 ((wq_completion)xfs-cil/dm-0){+.+.}-{0:0}, at: process_one_work+0x200/0x450 #1: ffffab3840ac7e68 ((work_completion)(&cil->xc_push_work)){+.+.}-{0:0}, at: process_one_work+0x200/0x450 #2: ffff8c2e4a887128 (&cil->xc_ctx_lock){++++}-{3:3}, at: xlog_cil_push_work+0xb7/0x670 [xfs] #3: ffffffffa6a63780 (rcu_read_lock){....}-{1:2}, at: blk_add_trace_bio+0x0/0x1f0 #4: ffffffffa6610620 (running_trace_lock){+.+.}-{2:2}, at: __blk_add_trace+0x3ef/0x480 Preemption disabled at: [] migrate_enable+0x45/0x140 CPU: 0 PID: 119 Comm: kworker/u2:2 Kdump: loaded Not tainted 5.14.0-25.rt21.25.light.el9.x86_64+debug #1 Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 Workqueue: xfs-cil/dm-0 xlog_cil_push_work [xfs] Call Trace: ? migrate_enable+0x45/0x140 dump_stack_lvl+0x57/0x7d ___might_sleep.cold+0xe3/0xf7 rt_spin_lock+0x3a/0xd0 ? __blk_add_trace+0x3ef/0x480 __blk_add_trace+0x3ef/0x480 blk_add_trace_bio+0x18d/0x1f0 trace_block_bio_queue+0xb5/0x150 submit_bio_checks+0x1f0/0x520 ? sched_clock_cpu+0xb/0x100 submit_bio_noacct+0x30/0x1d0 ? bio_associate_blkg+0x66/0x190 xlog_cil_push_work+0x1b6/0x670 [xfs] ? register_lock_class+0x43/0x4f0 ? xfs_swap_extents+0x5f0/0x5f0 [xfs] process_one_work+0x275/0x450 ? process_one_work+0x200/0x450 worker_thread+0x55/0x3c0 ? process_one_work+0x450/0x450 kthread+0x188/0x1a0 ? set_kthread_struct+0x40/0x40 ret_from_fork+0x22/0x30 To avoid this bug, we switch the trace lock to a raw spinlock. Signed-off-by: Wander Lairson Costa --- kernel/trace/blktrace.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index 1183c88634aa..a86e022f7155 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -34,7 +34,7 @@ static struct trace_array *blk_tr; static bool blk_tracer_enabled __read_mostly; static LIST_HEAD(running_trace_list); -static __cacheline_aligned_in_smp DEFINE_SPINLOCK(running_trace_lock); +static __cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(running_trace_lock); /* Select an alternative, minimalistic output than the original one */ #define TRACE_BLK_OPT_CLASSIC 0x1 @@ -121,12 +121,12 @@ static void trace_note_tsk(struct task_struct *tsk) struct blk_trace *bt; tsk->btrace_seq = blktrace_seq; - spin_lock_irqsave(&running_trace_lock, flags); + raw_spin_lock_irqsave(&running_trace_lock, flags); list_for_each_entry(bt, &running_trace_list, running_list) { trace_note(bt, tsk->pid, BLK_TN_PROCESS, tsk->comm, sizeof(tsk->comm), 0); } - spin_unlock_irqrestore(&running_trace_lock, flags); + raw_spin_unlock_irqrestore(&running_trace_lock, flags); } static void trace_note_time(struct blk_trace *bt) @@ -666,9 +666,9 @@ static int __blk_trace_startstop(struct request_queue *q, int start) blktrace_seq++; smp_mb(); bt->trace_state = Blktrace_running; - spin_lock_irq(&running_trace_lock); + raw_spin_lock_irq(&running_trace_lock); list_add(&bt->running_list, &running_trace_list); - spin_unlock_irq(&running_trace_lock); + raw_spin_unlock_irq(&running_trace_lock); trace_note_time(bt); ret = 0; @@ -676,9 +676,9 @@ static int __blk_trace_startstop(struct request_queue *q, int start) } else { if (bt->trace_state == Blktrace_running) { bt->trace_state = Blktrace_stopped; - spin_lock_irq(&running_trace_lock); + raw_spin_lock_irq(&running_trace_lock); list_del_init(&bt->running_list); - spin_unlock_irq(&running_trace_lock); + raw_spin_unlock_irq(&running_trace_lock); relay_flush(bt->rchan); ret = 0; } @@ -1608,9 +1608,9 @@ static int blk_trace_remove_queue(struct request_queue *q) if (bt->trace_state == Blktrace_running) { bt->trace_state = Blktrace_stopped; - spin_lock_irq(&running_trace_lock); + raw_spin_lock_irq(&running_trace_lock); list_del_init(&bt->running_list); - spin_unlock_irq(&running_trace_lock); + raw_spin_unlock_irq(&running_trace_lock); relay_flush(bt->rchan); } -- 2.27.0