From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f70.google.com (mail-io1-f70.google.com [209.85.166.70]) by kanga.kvack.org (Postfix) with ESMTP id 0CD228E0001 for ; Mon, 7 Jan 2019 04:52:34 -0500 (EST) Received: by mail-io1-f70.google.com with SMTP id p21so19049234iog.0 for ; Mon, 07 Jan 2019 01:52:34 -0800 (PST) Received: from merlin.infradead.org (merlin.infradead.org. [2001:8b0:10b:1231::1]) by mx.google.com with ESMTPS id n191si1150663itn.141.2019.01.07.01.52.33 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 07 Jan 2019 01:52:33 -0800 (PST) Date: Mon, 7 Jan 2019 10:52:17 +0100 From: Peter Zijlstra Subject: Re: possible deadlock in __wake_up_common_lock Message-ID: <20190107095217.GB2861@worktop.programming.kicks-ass.net> References: <000000000000f67ca2057e75bec3@google.com> <1194004c-f176-6253-a5fd-682472dccacc@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1194004c-f176-6253-a5fd-682472dccacc@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: syzbot , aarcange@redhat.com, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux@dominikbrodowski.net, mhocko@suse.com, rientjes@google.com, syzkaller-bugs@googlegroups.com, xieyisheng1@huawei.com, zhongjiang@huawei.com, Mel Gorman , Ingo Molnar , hannes@cmpxchg.org On Wed, Jan 02, 2019 at 01:51:01PM +0100, Vlastimil Babka wrote: > > -> #3 (&base->lock){-.-.}: > > __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline] > > _raw_spin_lock_irqsave+0x99/0xd0 kernel/locking/spinlock.c:152 > > lock_timer_base+0xbb/0x2b0 kernel/time/timer.c:937 > > __mod_timer kernel/time/timer.c:1009 [inline] > > mod_timer kernel/time/timer.c:1101 [inline] > > add_timer+0x895/0x1490 kernel/time/timer.c:1137 > > __queue_delayed_work+0x249/0x380 kernel/workqueue.c:1533 > > queue_delayed_work_on+0x1a2/0x1f0 kernel/workqueue.c:1558 > > queue_delayed_work include/linux/workqueue.h:527 [inline] > > schedule_delayed_work include/linux/workqueue.h:628 [inline] > > psi_group_change kernel/sched/psi.c:485 [inline] > > psi_task_change+0x3f1/0x5f0 kernel/sched/psi.c:534 > > psi_enqueue kernel/sched/stats.h:82 [inline] > > enqueue_task kernel/sched/core.c:727 [inline] > > activate_task+0x21a/0x430 kernel/sched/core.c:751 > > wake_up_new_task+0x527/0xd20 kernel/sched/core.c:2423 > > _do_fork+0x33b/0x11d0 kernel/fork.c:2247 > > kernel_thread+0x34/0x40 kernel/fork.c:2281 > > rest_init+0x28/0x372 init/main.c:409 > > arch_call_rest_init+0xe/0x1b > > start_kernel+0x873/0x8ae init/main.c:741 > > x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:470 > > x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:451 > > secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:243 That thing is fairly new; I don't think we used to have this dependency prior to PSI. Johannes, can we move that mod_timer out from under rq->lock? At worst we can use an irq_work to self-ipi.