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Message-ID: <1504545350.22981.16.camel@gmx.de>
Date: Mon, 04 Sep 2017 19:15:50 +0200
From: Mike Galbraith <efault@....de>
To: Peter Zijlstra <peterz@...radead.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Byungchul Park <max.byungchul.park@...il.com>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: hotplug lockdep splat (tip)
On Mon, 2017-09-04 at 16:23 +0200, Peter Zijlstra wrote:
> On Mon, Sep 04, 2017 at 09:55:02AM +0200, Peter Zijlstra wrote:
> > On Sun, Sep 03, 2017 at 08:59:35AM +0200, Mike Galbraith wrote:
> > >
> > > [ 126.626908] Unregister pv shared memory for cpu 1
> > > [ 126.631041]
> > > [ 126.631269] ======================================================
> > > [ 126.632442] WARNING: possible circular locking dependency detected
> > > [ 126.633599] 4.13.0.g06260ca-tip-lockdep #2 Tainted: G E
> > > [ 126.634380] ------------------------------------------------------
> > > [ 126.635124] stress-cpu-hotp/3156 is trying to acquire lock:
> > > [ 126.635804] ((complete)&st->done){+.+.}, at: [<ffffffff8108d19a>] takedown_cpu+0x8a/0xf0
> > > [ 126.636809]
> > > [ 126.636809] but task is already holding lock:
> > > [ 126.637567] (sparse_irq_lock){+.+.}, at: [<ffffffff81107ac7>] irq_lock_sparse+0x17/0x20
> > > [ 126.638665]
> >
> > https://lkml.kernel.org/r/20170829193416.GC32112@worktop.programming.kicks-ass.net
> >
> > I still need to write a coherent Changelog and comments for that :/
>
> How's this?
[ 138.241466] ======================================================
[ 138.242014] WARNING: possible circular locking dependency detected
[ 138.242802] 4.13.0.g90abd70-tip-lockdep #6 Tainted: G E
[ 138.243701] ------------------------------------------------------
[ 138.244540] cpuhp/0/12 is trying to acquire lock:
[ 138.245187] (cpuhp_state){+.+.}, at: [<ffffffff8108e50a>]
cpuhp_thread_fun+0x2a/0x160
[ 138.246312]
but now in release context of a crosslock acquired at
the following:
[ 138.247519] ((complete)&st->done#3){+.+.}, at: [<ffffffff8108e77f>]
cpuhp_issue_call+0x13f/0x170
[ 138.248745]
which lock already depends on the new lock.
[ 138.249861]
the existing dependency chain (in reverse order) is:
[ 138.250836]
-> #2 ((complete)&st->done#3){+.+.}:
[ 138.251732] __lock_acquire+0x116a/0x11c0
[ 138.252339] lock_acquire+0xbd/0x200
[ 138.252906] wait_for_completion+0x53/0x1a0
[ 138.253587] takedown_cpu+0x8a/0xf0
[ 138.254194] cpuhp_invoke_callback+0x1f6/0x830
[ 138.254906] cpuhp_down_callbacks+0x42/0x80
[ 138.255586] _cpu_down+0x14d/0x180
[ 138.256179] do_cpu_down+0x3e/0x60
[ 138.256774] cpu_down+0x10/0x20
[ 138.257295] cpu_subsys_offline+0x14/0x20
[ 138.257973] device_offline+0x8c/0xb0
[ 138.258548] online_store+0x40/0x80
[ 138.259094] dev_attr_store+0x18/0x30
[ 138.259668] sysfs_kf_write+0x44/0x60
[ 138.260213] kernfs_fop_write+0x113/0x1a0
[ 138.260873] __vfs_write+0x28/0x150
[ 138.261447] vfs_write+0xc7/0x1c0
[ 138.262009] SyS_write+0x49/0xa0
[ 138.262535] entry_SYSCALL_64_fastpath+0x1f/0xbe
[ 138.263276]
-> #1 (sparse_irq_lock){+.+.}:
[ 138.264070] __lock_acquire+0x116a/0x11c0
[ 138.264731] lock_acquire+0xbd/0x200
[ 138.265300] __mutex_lock+0x70/0x8e0
[ 138.265881] mutex_lock_nested+0x1b/0x20
[ 138.266515] irq_lock_sparse+0x17/0x20
[ 138.267127] irq_affinity_online_cpu+0x18/0xd0
[ 138.267813] cpuhp_invoke_callback+0x1f6/0x830
[ 138.268538] cpuhp_up_callbacks+0x37/0xb0
[ 138.269174] cpuhp_thread_fun+0x14f/0x160
[ 138.269829] smpboot_thread_fn+0x11a/0x1e0
[ 138.270490] kthread+0x152/0x190
[ 138.271055] ret_from_fork+0x2a/0x40
[ 138.271661]
-> #0 (cpuhp_state){+.+.}:
[ 138.272424] cpuhp_thread_fun+0x54/0x160
[ 138.273104] smpboot_thread_fn+0x11a/0x1e0
[ 138.273816] kthread+0x152/0x190
[ 138.274371] ret_from_fork+0x2a/0x40
[ 138.274958] 0xffffffffffffffff
[ 138.275450]
other info that might help us debug this:
[ 138.276552] Chain exists of:
cpuhp_state --> sparse_irq_lock --> (complete)&st-
>done#3
[ 138.278114] Possible unsafe locking scenario by crosslock:
[ 138.279122] CPU0 CPU1
[ 138.279777] ---- ----
[ 138.280418] lock(sparse_irq_lock);
[ 138.280936] lock((complete)&st->done#3);
[ 138.281511] lock(cpuhp_state);
[ 138.282322] unlock((complete)&st-
>done#3);
[ 138.283269]
*** DEADLOCK ***
[ 138.284147] 1 lock held by cpuhp/0/12:
[ 138.284688] #0: (&x->wait#2){-...}, at: [<ffffffff810e1b5d>]
complete+0x1d/0x60
[ 138.285734]
stack backtrace:
[ 138.286368] CPU: 0 PID: 12 Comm: cpuhp/0 Tainted:
G E 4.13.0.g90abd70-tip-lockdep #6
[ 138.287800] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.0.0-prebuilt.qemu-project.org 04/01/2014
[ 138.289324] Call Trace:
[ 138.289708] dump_stack+0x85/0xc5
[ 138.290199] print_circular_bug+0x2e9/0x2f7
[ 138.290805] check_prev_add+0x666/0x700
[ 138.291313] ? print_bfs_bug+0x40/0x40
[ 138.291866] ? trace_hardirqs_on+0xd/0x10
[ 138.292223] lock_commit_crosslock+0x410/0x5a0
[ 138.292620] complete+0x29/0x60
[ 138.292900] cpuhp_thread_fun+0xa1/0x160
[ 138.293233] ? cpuhp_thread_fun+0x2a/0x160
[ 138.293584] smpboot_thread_fn+0x11a/0x1e0
[ 138.293943] kthread+0x152/0x190
[ 138.294221] ? sort_range+0x30/0x30
[ 138.294521] ? kthread_create_on_node+0x40/0x40
[ 138.294920] ? kthread+0x10/0x190
[ 138.295203] ret_from_fork+0x2a/0x40
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