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=-13.1 required=3.0 tests=BAYES_00,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 44A59C433E4 for ; Mon, 10 Aug 2020 19:12:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 15A4322BEB for ; Mon, 10 Aug 2020 19:12:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597086760; bh=Nt89UCIAMnGmAbLwKElLJHQuRa2Rs0pdKFbBiIE+piY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=N7gghenS3vTaLaRHqMO1eg+bBrXLqFOjagh99+ye9iDR53TCcsKwz69RWUJCC52Nv qfLtHSDsSLikrX+S6iEOYmHrkU1xvrebCO54Xir8v/HKqYL2BWHKzpyAm655odwmbe b7/QrVqL6rNKGvjHzT4kcttFQoquuWHgZMM80jR4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729591AbgHJTMj (ORCPT ); Mon, 10 Aug 2020 15:12:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:42258 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728472AbgHJTMb (ORCPT ); Mon, 10 Aug 2020 15:12:31 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (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 58FD022BEA; Mon, 10 Aug 2020 19:12:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597086750; bh=Nt89UCIAMnGmAbLwKElLJHQuRa2Rs0pdKFbBiIE+piY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dRHHHusq7nAfz+pfPI3F8/ht54VSlOf+5LuDcfjl9n9Y7kXSOsYbZmSuoXwtlJtXD EIAzVugNAXSldKQU14gXYCFt8oW0EiZYKyuUgZtqVjF9X4dnKUH/ktsd9uNMyCFuz6 Xsp6CbPMtzZwtsRmlxsoPUjEzsIriHdyKW/E1MSI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Paul E. McKenney" , Andrew Morton , linux-mm@kvack.org, Shakeel Butt , Joel Fernandes , Sasha Levin Subject: [PATCH AUTOSEL 5.4 26/45] mm/mmap.c: Add cond_resched() for exit_mmap() CPU stalls Date: Mon, 10 Aug 2020 15:11:34 -0400 Message-Id: <20200810191153.3794446-26-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200810191153.3794446-1-sashal@kernel.org> References: <20200810191153.3794446-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" [ Upstream commit 0a3b3c253a1eb2c7fe7f34086d46660c909abeb3 ] 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: 3-....: (20998 ticks this GP) idle=4ea/1/0x4000000000000002 softirq=556558/556558 fqs=5190 (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: Reviewed-by: Shakeel Butt Reviewed-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- mm/mmap.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/mmap.c b/mm/mmap.c index ea1ba2db4f4fe..a3584a90c55c2 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3172,6 +3172,7 @@ 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); } -- 2.25.1