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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E19EBC433DF for ; Tue, 23 Jun 2020 00:21:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C21B720EDD for ; Tue, 23 Jun 2020 00:21:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592871714; bh=v8L16gFdtdEwBmp5EsUutLkEAAPJcRQNFOZhQugVOR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=f9V9j5b2xj4vRgCHLBRqm6gl8fu/xBjJul2dsLpHXuNn9jLvBzA1UWm43N4LfdPDA WNYBSRRt1esAmf3dQYIW7lJUrvKMV1g3320dgJdVgWvILY66z2nmC06MvV0o5mEu5l hxg9QEEZleo0l5wZYC3RDUcNvG413ZUa+ZrpY8go= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731561AbgFWAVw (ORCPT ); Mon, 22 Jun 2020 20:21:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:48026 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730421AbgFWAVu (ORCPT ); Mon, 22 Jun 2020 20:21:50 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A095320780; Tue, 23 Jun 2020 00:21:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592871709; bh=v8L16gFdtdEwBmp5EsUutLkEAAPJcRQNFOZhQugVOR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aKcKnGJjD3+Wzb8bYF+tGmsDY+grnvXJ5JTdH/8kzqKBpHK96KSXU8UarB+Ube8+2 rbRAD/XbuBOkMkA5mQWGFADMjcr6EGSGw3uRgAp+WIvJiFkIw+feV2wgqXamBds6qs 1pv1LNQtQKd2ZsNXVYLSxsPCnLw0MuP7Ek1e7Uzc= From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" , linux-mm@kvack.org Subject: [PATCH tip/core/rcu 02/26] mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls Date: Mon, 22 Jun 2020 17:21:23 -0700 Message-Id: <20200623002147.25750-2-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200623002128.GA25456@paulmck-ThinkPad-P72> References: <20200623002128.GA25456@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" A large process running on a heavily loaded system can encounter the following RCU CPU stall warning: rcu: INFO: rcu_sched self-detected stall on CPU rcu: \x093-....: (20998 ticks this GP) idle=4ea/1/0x4000000000000002 softirq=556558/556558 fqs=5190 \x09(t=21013 jiffies g=1005461 q=132576) NMI backtrace for cpu 3 CPU: 3 PID: 501900 Comm: aio-free-ring-w Kdump: loaded Not tainted 5.2.9-108_fbk12_rc3_3858_gb83b75af7909 #1 Hardware name: Wiwynn HoneyBadger/PantherPlus, BIOS HBM6.71 02/03/2016 Call Trace: dump_stack+0x46/0x60 nmi_cpu_backtrace.cold.3+0x13/0x50 ? lapic_can_unplug_cpu.cold.27+0x34/0x34 nmi_trigger_cpumask_backtrace+0xba/0xca rcu_dump_cpu_stacks+0x99/0xc7 rcu_sched_clock_irq.cold.87+0x1aa/0x397 ? tick_sched_do_timer+0x60/0x60 update_process_times+0x28/0x60 tick_sched_timer+0x37/0x70 __hrtimer_run_queues+0xfe/0x270 hrtimer_interrupt+0xf4/0x210 smp_apic_timer_interrupt+0x5e/0x120 apic_timer_interrupt+0xf/0x20 RIP: 0010:kmem_cache_free+0x223/0x300 Code: 88 00 00 00 0f 85 ca 00 00 00 41 8b 55 18 31 f6 f7 da 41 f6 45 0a 02 40 0f 94 c6 83 c6 05 9c 41 5e fa e8 a0 a7 01 00 41 56 9d <49> 8b 47 08 a8 03 0f 85 87 00 00 00 65 48 ff 08 e9 3d fe ff ff 65 RSP: 0018:ffffc9000e8e3da8 EFLAGS: 00000206 ORIG_RAX: ffffffffffffff13 RAX: 0000000000020000 RBX: ffff88861b9de960 RCX: 0000000000000030 RDX: fffffffffffe41e8 RSI: 000060777fe3a100 RDI: 000000000001be18 RBP: ffffea00186e7780 R08: ffffffffffffffff R09: ffffffffffffffff R10: ffff88861b9dea28 R11: ffff88887ffde000 R12: ffffffff81230a1f R13: ffff888854684dc0 R14: 0000000000000206 R15: ffff8888547dbc00 ? remove_vma+0x4f/0x60 remove_vma+0x4f/0x60 exit_mmap+0xd6/0x160 mmput+0x4a/0x110 do_exit+0x278/0xae0 ? syscall_trace_enter+0x1d3/0x2b0 ? handle_mm_fault+0xaa/0x1c0 do_group_exit+0x3a/0xa0 __x64_sys_exit_group+0x14/0x20 do_syscall_64+0x42/0x100 entry_SYSCALL_64_after_hwframe+0x44/0xa9 And on a PREEMPT=n kernel, the "while (vma)" loop in exit_mmap() can run for a very long time given a large process. This commit therefore adds a cond_resched() to this loop, providing RCU any needed quiescent states. Cc: Andrew Morton Cc: Signed-off-by: Paul E. McKenney --- mm/mmap.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/mmap.c b/mm/mmap.c index 59a4682..972f839 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3159,6 +3159,7 @@ void exit_mmap(struct mm_struct *mm) if (vma->vm_flags & VM_ACCOUNT) nr_accounted += vma_pages(vma); vma = remove_vma(vma); + cond_resched(); } vm_unacct_memory(nr_accounted); } -- 2.9.5