RE: [PATCH 1/6] ACPI/EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag.

From: Zheng, Lv
Date: Thu Nov 20 2014 - 19:44:08 EST

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Hi, Shutemov

> From: Kirill A. Shutemov [mailto:kirill@xxxxxxxxxxxxx]
> Sent: Friday, November 21, 2014 5:34 AM
>
> On Thu, Nov 20, 2014 at 02:20:53AM +0000, Zheng, Lv wrote:
> > Since you have environment to trigger this.
> > Could you also help to check if the fix can work?
> > I've just sent them as RFC to this thread.
>
> With these two patchse on top of my -next snapshot I still see the issue:
>
> [ 0.324119] ======================================================
> [ 0.324125] [ INFO: possible circular locking dependency detected ]
> [ 0.324132] 3.18.0-rc5-next-20141119-07477-g4c45e54745b2 #80 Not tainted
> [ 0.324138] -------------------------------------------------------
> [ 0.324144] swapper/3/0 is trying to acquire lock:
> [ 0.324149] (&(&ec->lock)->rlock){-.....}, at: [<ffffffff814cb803>] acpi_ec_gpe_handler+0x21/0xfc
> [ 0.324165]
> but task is already holding lock:
> [ 0.324171] (&(*(&acpi_gbl_gpe_lock))->rlock){-.....}, at: [<ffffffff814c3b3e>] acpi_os_acquire_lock+0xe/0x10
> [ 0.324185]
> which lock already depends on the new lock.
>
> [ 0.324193]
> the existing dependency chain (in reverse order) is:
> [ 0.324200]
> -> #1 (&(*(&acpi_gbl_gpe_lock))->rlock){-.....}:
> [ 0.324209] [<ffffffff81158f0f>] lock_acquire+0xdf/0x2d0
> [ 0.324218] [<ffffffff81b004c0>] _raw_spin_lock_irqsave+0x50/0x70
> [ 0.324228] [<ffffffff814c3b3e>] acpi_os_acquire_lock+0xe/0x10
> [ 0.324235] [<ffffffff814d9945>] acpi_enable_gpe+0x27/0x75
> [ 0.324244] [<ffffffff814cc960>] acpi_ec_start+0x67/0x88
> [ 0.324251] [<ffffffff81af4ca9>] ec_install_handlers+0x41/0xa4
> [ 0.324258] [<ffffffff823e4134>] acpi_ec_ecdt_probe+0x1a9/0x1ea
> [ 0.324267] [<ffffffff823e395e>] acpi_init+0x8b/0x26e
> [ 0.324275] [<ffffffff81002148>] do_one_initcall+0xd8/0x210
> [ 0.324283] [<ffffffff8239c1dc>] kernel_init_freeable+0x1f5/0x282
> [ 0.324293] [<ffffffff81aea0fe>] kernel_init+0xe/0xf0
> [ 0.324300] [<ffffffff81b011bc>] ret_from_fork+0x7c/0xb0
> [ 0.324307]
> -> #0 (&(&ec->lock)->rlock){-.....}:
> [ 0.324315] [<ffffffff811585af>] __lock_acquire+0x210f/0x2220
> [ 0.324323] [<ffffffff81158f0f>] lock_acquire+0xdf/0x2d0
> [ 0.324330] [<ffffffff81b004c0>] _raw_spin_lock_irqsave+0x50/0x70
> [ 0.324338] [<ffffffff814cb803>] acpi_ec_gpe_handler+0x21/0xfc
> [ 0.324346] [<ffffffff814d68e0>] acpi_ev_gpe_dispatch+0xb9/0x12e
> [ 0.324353] [<ffffffff814d6a5a>] acpi_ev_gpe_detect+0x105/0x227
> [ 0.324360] [<ffffffff814d8af5>] acpi_ev_sci_xrupt_handler+0x22/0x38
> [ 0.324368] [<ffffffff814c2dae>] acpi_irq+0x16/0x31
> [ 0.324375] [<ffffffff8116ecbf>] handle_irq_event_percpu+0x6f/0x540
> [ 0.324384] [<ffffffff8116f1d1>] handle_irq_event+0x41/0x70
> [ 0.324392] [<ffffffff81171ee6>] handle_fasteoi_irq+0x86/0x140
> [ 0.324399] [<ffffffff81075a22>] handle_irq+0x22/0x40
> [ 0.324408] [<ffffffff81b0436f>] do_IRQ+0x4f/0xf0
> [ 0.324416] [<ffffffff81b02072>] ret_from_intr+0x0/0x1a
> [ 0.324423] [<ffffffff8107e7a3>] default_idle+0x23/0x260
> [ 0.324430] [<ffffffff8107f37f>] arch_cpu_idle+0xf/0x20
> [ 0.324438] [<ffffffff8114a95b>] cpu_startup_entry+0x36b/0x5b0
> [ 0.324445] [<ffffffff810a8d24>] start_secondary+0x1a4/0x1d0
> [ 0.324454]
> other info that might help us debug this:
>
> [ 0.324462] Possible unsafe locking scenario:
>
> [ 0.324468] CPU0 CPU1
> [ 0.324473] ---- ----
> [ 0.324477] lock(&(*(&acpi_gbl_gpe_lock))->rlock);
> [ 0.324483] lock(&(&ec->lock)->rlock);
> [ 0.324490] lock(&(*(&acpi_gbl_gpe_lock))->rlock);
> [ 0.324498] lock(&(&ec->lock)->rlock);
> [ 0.324503]

Let me convert this into call stack:
CPU0 CPU1
acpi_irq
+GPE acpi_ev_gpe_dispatch
acpi_bus_init
acpi_ec_ecdt_probe
acpi_install_gpe_handler()
+EC acpi_ec_start
+GPE acpi_enable_gpe
-GPE
-EC
+EC acpi_ec_gpe_handler
-EC
-GPE

I used + to indicate spin_lock() and - to indicate spin_unlock().
GPE to indicate acpi_gbl_gpe_lock, EC to indicate ec->lock.

Are you sure you still can see this?
Please help to check the [RFC PATCH 2] to see if the following code is exactly applied:
+ /*
+ * There is no protection around the namespace node
+ * and the GPE handler to ensure a safe destruction
+ * because:
+ * 1. The namespace node is expected to always
+ * exist after loading a table.
+ * 2. The GPE handler is expected to be flushed by
+ * acpi_os_wait_events_complete() before the
+ * destruction.
+ */
+ acpi_os_release_lock
+ (acpi_gbl_gpe_lock, flags);
+ int_status |=
+ gpe_handler_info->
+ address(gpe_device,
+ gpe_number,
+ gpe_handler_info->
+ context);

This is where acpi_ec_gpe_handler() will be invoked.

+ flags =
+ acpi_os_acquire_lock
+ (acpi_gbl_gpe_lock);

So when acpi_ec_gpe_handler() is invoked, GPE lock is release.
There should be no reason you can see this warning, because the call stack will be:

CPU0 CPU1
CPU0 CPU1
acpi_irq
+GPE acpi_ev_gpe_dispatch
acpi_bus_init
acpi_ec_ecdt_probe
acpi_install_gpe_handler()
+EC acpi_ec_start
+GPE acpi_enable_gpe
-GPE
-EC
-GPE
+EC acpi_ec_gpe_handler
-EC
+GPE
-GPE

When acpi_ec_gpe_handler() is invoked, there is no acpi_gbl_gpe_lock locked.
So I really cannot understand your test result.
Could you confirm this again?

Maybe I just don't understand how this warning is generated, and this is just a kind of warning that we can ignore.
Let me ask Peter and Ingo to check if this is just a limitation of lockdep.

Thanks and best regards
-Lv

> *** DEADLOCK ***
>
> [ 0.324510] 1 lock held by swapper/3/0:
> [ 0.324514] #0: (&(*(&acpi_gbl_gpe_lock))->rlock){-.....}, at: [<ffffffff814c3b3e>] acpi_os_acquire_lock+0xe/0x10
> [ 0.324528]
> stack backtrace:
> [ 0.324535] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 3.18.0-rc5-next-20141119-07477-g4c45e54745b2 #80
> [ 0.324543] Hardware name: LENOVO 3460CC6/3460CC6, BIOS G6ET93WW (2.53 ) 02/04/2013
> [ 0.324550] ffffffff82cae120 ffff88011e2c3ba8 ffffffff81af484e 0000000000000011
> [ 0.324560] ffffffff82cae120 ffff88011e2c3bf8 ffffffff81af3361 0000000000000001
> [ 0.324569] ffff88011e2c3c58 ffff88011e2c3bf8 ffff8801193f92b0 ffff8801193f9b00
> [ 0.324579] Call Trace:
> [ 0.324582] <IRQ> [<ffffffff81af484e>] dump_stack+0x4c/0x6e
> [ 0.324593] [<ffffffff81af3361>] print_circular_bug+0x2b2/0x2c3
> [ 0.324601] [<ffffffff811585af>] __lock_acquire+0x210f/0x2220
> [ 0.324609] [<ffffffff81158f0f>] lock_acquire+0xdf/0x2d0
> [ 0.324616] [<ffffffff814cb803>] ? acpi_ec_gpe_handler+0x21/0xfc
> [ 0.324624] [<ffffffff81b004c0>] _raw_spin_lock_irqsave+0x50/0x70
> [ 0.324631] [<ffffffff814cb803>] ? acpi_ec_gpe_handler+0x21/0xfc
> [ 0.324640] [<ffffffff814e08f7>] ? acpi_hw_write+0x4b/0x52
> [ 0.324646] [<ffffffff814cb803>] acpi_ec_gpe_handler+0x21/0xfc
> [ 0.324653] [<ffffffff814d68e0>] acpi_ev_gpe_dispatch+0xb9/0x12e
> [ 0.324660] [<ffffffff814d6a5a>] acpi_ev_gpe_detect+0x105/0x227
> [ 0.324668] [<ffffffff814d8af5>] acpi_ev_sci_xrupt_handler+0x22/0x38
> [ 0.324675] [<ffffffff814c2dae>] acpi_irq+0x16/0x31
> [ 0.324683] [<ffffffff8116ecbf>] handle_irq_event_percpu+0x6f/0x540
> [ 0.324691] [<ffffffff8116f1d1>] handle_irq_event+0x41/0x70
> [ 0.324698] [<ffffffff81171e88>] ? handle_fasteoi_irq+0x28/0x140
> [ 0.324705] [<ffffffff81171ee6>] handle_fasteoi_irq+0x86/0x140
> [ 0.324712] [<ffffffff81075a22>] handle_irq+0x22/0x40
> [ 0.324719] [<ffffffff81b0436f>] do_IRQ+0x4f/0xf0
> [ 0.324725] [<ffffffff81b02072>] common_interrupt+0x72/0x72
> [ 0.324731] <EOI> [<ffffffff810b8986>] ? native_safe_halt+0x6/0x10
> [ 0.324743] [<ffffffff81154efd>] ? trace_hardirqs_on+0xd/0x10
> [ 0.324750] [<ffffffff8107e7a3>] default_idle+0x23/0x260
> [ 0.324757] [<ffffffff8107f37f>] arch_cpu_idle+0xf/0x20
> [ 0.324763] [<ffffffff8114a95b>] cpu_startup_entry+0x36b/0x5b0
> [ 0.324771] [<ffffffff810a8d24>] start_secondary+0x1a4/0x1d0
>
>
> >
> > Thanks and best regards
> > -Lv
> >
> > > From: Kirill A. Shutemov [mailto:kirill@xxxxxxxxxxxxx]
> > > Sent: Wednesday, November 19, 2014 8:16 PM
> > > To: Rafael J. Wysocki
> > > Cc: Zheng, Lv; Wysocki, Rafael J; Brown, Len; Lv Zheng; linux-kernel@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx
> > > Subject: Re: [PATCH 1/6] ACPI/EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag.
> > >
> > > On Tue, Nov 18, 2014 at 10:20:11PM +0100, Rafael J. Wysocki wrote:
> > > > On Tuesday, November 18, 2014 03:23:28 PM Kirill A. Shutemov wrote:
> > > > > On Wed, Nov 05, 2014 at 02:52:36AM +0000, Zheng, Lv wrote:
> > > >
> > > > [cut]
> > > >
> > > > >
> > > > > Here's lockdep warning I see on -next:
> > > >
> > > > Is patch [1/6] sufficient to trigger this or do you need all [1-4/6]?
> > >
> > > I only saw it on -next. I've tried to apply patches directly on -rc5 and
> > > don't see the warning. I don't have time for proper bisecting, sorry.
> > >
> > > --
> > > Kirill A. Shutemov
>
> --
> Kirill A. Shutemov
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Next message: Thomas Gleixner: "Re: frequent lockups in 3.18rc4"
Previous message: ethan zhao: "Re: [PATCH 1/3] intel_pstate: skip the driver if Sun server has ACPI _PPC method"
In reply to: Kirill A. Shutemov: "Re: [PATCH 1/6] ACPI/EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag."
Next in thread: Zheng, Lv: "RE: [PATCH 1/6] ACPI/EC: Introduce STARTED/STOPPED flags to replace BLOCKED flag."
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