Hi Vincent,
The below patch fixed deadlock.
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -105,7 +105,7 @@ static inline bool pm_runtime_callbacks_present(struct device *dev)
static inline void pm_runtime_mark_last_busy(struct device *dev)
{
- WRITE_ONCE(dev->power.last_busy, ktime_to_ns(ktime_get()));
+ WRITE_ONCE(dev->power.last_busy, ktime_get_mono_fast_ns());
}
Regards,
Biju
> -----Original Message-----
> From: Biju Das
> Sent: 25 January 2019 14:26
> To: 'Vincent Guittot' <vincent.guittot@xxxxxxxxxx>
> Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>; Sergei Shtylyov
> <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>; Rob Herring
> <robh+dt@xxxxxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; Simon
> Horman <horms@xxxxxxxxxxxx>; Magnus Damm
> <magnus.damm@xxxxxxxxx>; Linux-Renesas <linux-renesas-
> soc@xxxxxxxxxxxxxxx>; open list:OPEN FIRMWARE AND FLATTENED DEVICE
> TREE BINDINGS <devicetree@xxxxxxxxxxxxxxx>; Geert Uytterhoeven
> <geert+renesas@xxxxxxxxx>; Chris Paterson
> <Chris.Paterson2@xxxxxxxxxxx>; Daniel Lezcano
> <daniel.lezcano@xxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>; John
> Stultz <john.stultz@xxxxxxxxxx>; Fabrizio Castro
> <fabrizio.castro@xxxxxxxxxxxxxx>; Samuel Holland <samuel@xxxxxxxxxxxx>
> Subject: RE: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device nodes
>
> Hi Vincent,
>
> Thanks for the update. I am still seeing the same deadlock.
>
> diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> index fb5e2b6..a96641a 100644
> --- a/drivers/base/power/runtime.c
> +++ b/drivers/base/power/runtime.c
> @@ -155,7 +155,7 @@ u64 pm_runtime_autosuspend_expiration(struct
> device *dev)
>
> expires = READ_ONCE(dev->power.last_busy);
> expires += (u64)autosuspend_delay * NSEC_PER_MSEC;
> - if (expires > ktime_to_ns(ktime_get()))
> + if (expires > ktime_get_mono_fast_ns())
> return expires; /* Expires in the future */
>
> return 0;
> @@ -921,7 +921,7 @@ static enum hrtimer_restart
> pm_suspend_timer_fn(struct hrtimer *timer)
> * If 'expires' is after the current time, we've been called
> * too early.
> */
> - if (expires > 0 && expires < ktime_to_ns(ktime_get())) {
> + if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
> dev->power.timer_expires = 0;
> rpm_suspend(dev, dev->power.timer_autosuspends ?
> (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC); @@ -940,7 +940,7
> @@ static enum hrtimer_restart pm_suspend_timer_fn(struct hrtimer
> *timer) int pm_schedule_suspend(struct device *dev, unsigned int delay) {
> unsigned long flags;
> - ktime_t expires;
> + u64 expires;
> int retval;
>
> spin_lock_irqsave(&dev->power.lock, flags); @@ -957,8 +957,8 @@ int
> pm_schedule_suspend(struct device *dev, unsigned int delay)
> /* Other scheduled or pending requests need to be canceled. */
> pm_runtime_cancel_pending(dev);
>
> - expires = ktime_add(ktime_get(), ms_to_ktime(delay));
> - dev->power.timer_expires = ktime_to_ns(expires);
> + expires = ktime_get_mono_fast_ns() + ((u64)delay *
> NSEC_PER_MSEC);
> + dev->power.timer_expires = expires;
> dev->power.timer_autosuspends = 0;
> hrtimer_start(&dev->power.suspend_timer, expires,
> HRTIMER_MODE_ABS);
>
>
> please find the logs.
>
> root@salvator-x:~# echo e60f0000.timer >
> /sys/devices/system/clocksource/clocksource0/current_clocksource
> [ 42.769260]
> [ 42.770760] ============================================
> [ 42.776068] WARNING: possible recursive locking detected
> [ 42.781378] 5.0.0-rc3-next-20190125-00001-gfa6709c-dirty #33 Not tainted
> [ 42.788076] --------------------------------------------
> [ 42.793385] migration/0/11 is trying to acquire lock:
> [ 42.798435] 00000000b43b7183 (tk_core.seq){----}, at:
> rpm_resume+0x5f0/0x7a8
> [ 42.805497]
> [ 42.805497] but task is already holding lock:
> [ 42.811326] 00000000b43b7183 (tk_core.seq){----}, at:
> multi_cpu_stop+0x8c/0x140
> [ 42.818641]
> [ 42.818641] other info that might help us debug this:
> [ 42.825165] Possible unsafe locking scenario:
> [ 42.825165]
> [ 42.831080] CPU0
> [ 42.833521] ----
> [ 42.835962] lock(tk_core.seq);
> [ 42.839185] lock(tk_core.seq);
> [ 42.842409]
> [ 42.842409] *** DEADLOCK ***
> [ 42.842409]
> [ 42.848328] May be due to missing lock nesting notation
> [ 42.848328]
> [ 42.855115] 4 locks held by migration/0/11:
> [ 42.859293] #0: 00000000a7511731 (timekeeper_lock){-.-.}, at:
> change_clocksource+0x2c/0x118
> [ 42.867738] #1: 00000000b43b7183 (tk_core.seq){----}, at:
> multi_cpu_stop+0x8c/0x140
> [ 42.875484] #2: 00000000b54c38a2 (&ch->lock){....}, at:
> sh_cmt_start+0x28/0x200
> [ 42.882887] #3: 0000000010d14eec (&(&dev->power.lock)->rlock){-...}, at:
> __rpm_callback+0xbc/0x1e8
> [ 42.891937]
> [ 42.891937] stack backtrace:
> [ 42.896294] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.0.0-rc3-next-
> 20190125-00001-gfa6709c-dirty #33
> [ 42.905860] Hardware name: Renesas Salvator-X 2nd version board based
> on r8a7796 (DT)
> [ 42.913689] Call trace:
> [ 42.916137] dump_backtrace+0x0/0x178
> [ 42.919796] show_stack+0x14/0x20
> [ 42.923111] dump_stack+0xb0/0xec
> [ 42.926425] __lock_acquire+0xfb4/0x1c08
> [ 42.930345] lock_acquire+0xd0/0x268
> [ 42.933917] ktime_get+0x5c/0x108
> [ 42.937229] rpm_resume+0x5f0/0x7a8
> [ 42.940714] __pm_runtime_resume+0x50/0x98
> [ 42.944807] sh_cmt_start+0x84/0x200
> [ 42.948380] sh_cmt_clocksource_enable+0x28/0x48
> [ 42.952995] change_clocksource+0x84/0x118
> [ 42.957087] multi_cpu_stop+0x8c/0x140
> [ 42.960834] cpu_stopper_thread+0xac/0x120
> [ 42.964931] smpboot_thread_fn+0x1ac/0x2c8
> [ 42.969024] kthread+0x12c/0x130
> [ 42.972249] ret_from_fork+0x10/0x18
>
> Regards,
> Biju
>
> > -----Original Message-----
> > From: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
> > Sent: 25 January 2019 14:06
> > Subject: Re: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device
> > nodes
> >
> > Hi Biju,
> >
> > It seems that the call of mark_last_busy in rpm_resume raises this
> problem.
> > We have the sequence:
> > change_clocksource
> >
> > write_seqcount_begin
> > ...
> > timekeeping_update
> > ...
> > sh_cmt_clocksource_enable
> > ...
> > rpm_resume
> > pm_runtime_mark_last_busy
> > ktime_get
> > do
> > read_seqcount_begin
> > while read_seqcount_retry
> > ....
> > write_seqcount_end
> >
> > In fact, we should be safe because we haven't yet changed the
> > clocksource as we are enabling the clocksource that will be used for the
> switch.
> >
> > Can you try the patch below ?
> > It uses ktime_get_mono_fast_ns instead which is lock safe for such
> > case
> >
> > ---
> > drivers/base/power/runtime.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/base/power/runtime.c
> > b/drivers/base/power/runtime.c index 457be03..708a13f 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -130,7 +130,7 @@ u64 pm_runtime_autosuspend_expiration(struct
> > device *dev) {
> > int autosuspend_delay;
> > u64 last_busy, expires = 0;
> > -u64 now = ktime_to_ns(ktime_get());
> > +u64 now = ktime_get_mono_fast_ns();
> >
> > if (!dev->power.use_autosuspend)
> > goto out;
> > @@ -909,7 +909,7 @@ static enum hrtimer_restart
> > pm_suspend_timer_fn(struct hrtimer *timer)
> > * If 'expires' is after the current time, we've been called
> > * too early.
> > */
> > -if (expires > 0 && expires < ktime_to_ns(ktime_get())) {
> > +if (expires > 0 && expires < ktime_get_mono_fast_ns()) {
> > dev->power.timer_expires = 0;
> > rpm_suspend(dev, dev->power.timer_autosuspends ?
> > (RPM_ASYNC | RPM_AUTO) : RPM_ASYNC); @@ -928,7
> > +928,7 @@ static enum hrtimer_restart pm_suspend_timer_fn(struct
> > hrtimer *timer) int pm_schedule_suspend(struct device *dev, unsigned
> > int
> > delay) {
> > unsigned long flags;
> > -ktime_t expires;
> > +u64 expires;
> > int retval;
> >
> > spin_lock_irqsave(&dev->power.lock, flags); @@ -945,8 +945,8 @@
> int
> > pm_schedule_suspend(struct device *dev, unsigned int delay)
> > /* Other scheduled or pending requests need to be canceled. */
> > pm_runtime_cancel_pending(dev);
> >
> > -expires = ktime_add(ktime_get(), ms_to_ktime(delay));
> > -dev->power.timer_expires = ktime_to_ns(expires);
> > +expires = ktime_get_mono_fast_ns() + (u64)delay *
> > NSEC_PER_MSEC);
> > +dev->power.timer_expires = expires;
> > dev->power.timer_autosuspends = 0;
> > hrtimer_start(&dev->power.suspend_timer, expires,
> HRTIMER_MODE_ABS);
> >
> > --
> > 2.7.4
> >
> > Le Friday 25 Jan 2019 à 12:26:54 (+0000), Biju Das a écrit :
> > > Hi All,
> > >
> > > I have enabled lock debugging and it is showing "possible recursive
> > > locking
> > detected "with the patch ("8234f6734c5d74ac794e5517437f51c57d65f865"
> > PM-runtime: Switch autosuspend over to using hrtimers)
> > >
> > > root@salvator-x:~# echo e60f0000.timer >
> > /sys/devices/system/clocksource/clocksource0/current_clocksource
> > > [ 67.995854]
> > > [ 67.997354] ============================================
> > > [ 68.002663] WARNING: possible recursive locking detected
> > > [ 68.007974] 5.0.0-rc3-next-20190125-00005-g382822b #31 Not tainted
> > > [ 68.014150] --------------------------------------------
> > > [ 68.019459] migration/0/11 is trying to acquire lock:
> > > [ 68.024509] 0000000065de5fdf (tk_core.seq){----}, at:
> > rpm_resume+0x5f0/0x7a8
> > > [ 68.031570]
> > > [ 68.031570] but task is already holding lock:
> > > [ 68.037399] 0000000065de5fdf (tk_core.seq){----}, at:
> > multi_cpu_stop+0x8c/0x140
> > > [ 68.044714]
> > > [ 68.044714] other info that might help us debug this:
> > > [ 68.051237] Possible unsafe locking scenario:
> > > [ 68.051237]
> > > [ 68.057153] CPU0
> > > [ 68.059594] ----
> > > [ 68.062034] lock(tk_core.seq);
> > > [ 68.065258] lock(tk_core.seq);
> > > [ 68.068482]
> > > [ 68.068482] *** DEADLOCK ***
> > > [ 68.068482]
> > > [ 68.074402] May be due to missing lock nesting notation
> > > [ 68.074402]
> > > [ 68.081188] 4 locks held by migration/0/11:
> > > [ 68.085366] #0: 00000000463b6446 (timekeeper_lock){-.-.}, at:
> > change_clocksource+0x2c/0x118
> > > [ 68.093812] #1: 0000000065de5fdf (tk_core.seq){----}, at:
> > multi_cpu_stop+0x8c/0x140
> > > [ 68.101558] #2: 0000000098b45550 (&ch->lock){....}, at:
> > sh_cmt_start+0x28/0x200
> > > [ 68.108961] #3: 00000000da0f4e80 (&(&dev->power.lock)->rlock){-...},
> at:
> > __rpm_callback+0xbc/0x1e8
> > > [ 68.118011]
> > > [ 68.118011] stack backtrace:
> > > [ 68.122368] CPU: 0 PID: 11 Comm: migration/0 Not tainted 5.0.0-rc3-
> next-
> > 20190125-00005-g382822b #31
> > > [ 68.131412] Hardware name: Renesas Salvator-X 2nd version board
> based
> > on r8a7796 (DT)
> > > [ 68.139240] Call trace:
> > > [ 68.141687] dump_backtrace+0x0/0x178
> > > [ 68.145346] show_stack+0x14/0x20
> > > [ 68.148661] dump_stack+0xb0/0xec
> > > [ 68.151975] __lock_acquire+0xfb4/0x1c08
> > > [ 68.155894] lock_acquire+0xd0/0x268
> > > [ 68.159467] ktime_get+0x5c/0x108
> > > [ 68.162779] rpm_resume+0x5f0/0x7a8
> > > [ 68.166265] __pm_runtime_resume+0x50/0x98
> > > [ 68.170358] sh_cmt_start+0x84/0x200
> > > [ 68.173931] sh_cmt_clocksource_enable+0x28/0x48
> > > [ 68.178546] change_clocksource+0x84/0x118
> > > [ 68.182639] multi_cpu_stop+0x8c/0x140
> > > [ 68.186385] cpu_stopper_thread+0xac/0x120
> > > [ 68.190481] smpboot_thread_fn+0x1ac/0x2c8
> > > [ 68.194574] kthread+0x12c/0x130
> > > [ 68.197800] ret_from_fork+0x10/0x18
> > >
> > > Regards,
> > > Biju
> > >
> > > > -----Original Message-----
> > > > From: Biju Das
> > > > Sent: 25 January 2019 11:27
> > > > To: 'Geert Uytterhoeven' <geert@xxxxxxxxxxxxxx>; Vincent Guittot
> > > > <vincent.guittot@xxxxxxxxxx>; Sergei Shtylyov
> > > > <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>
> > > > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Mark Rutland
> > > > <mark.rutland@xxxxxxx>; Simon Horman <horms@xxxxxxxxxxxx>;
> > Magnus
> > > > Damm <magnus.damm@xxxxxxxxx>; Linux-Renesas <linux-renesas-
> > > > soc@xxxxxxxxxxxxxxx>; open list:OPEN FIRMWARE AND FLATTENED
> > DEVICE
> > > > TREE BINDINGS <devicetree@xxxxxxxxxxxxxxx>; Geert Uytterhoeven
> > > > <geert+renesas@xxxxxxxxx>; Chris Paterson
> > > > <Chris.Paterson2@xxxxxxxxxxx>; Daniel Lezcano
> > > > <daniel.lezcano@xxxxxxxxxx>; Thomas Gleixner <tglx@xxxxxxxxxxxxx>;
> > > > John Stultz <john.stultz@xxxxxxxxxx>; Fabrizio Castro
> > > > <fabrizio.castro@xxxxxxxxxxxxxx>; Samuel Holland
> > > > <samuel@xxxxxxxxxxxx>
> > > > Subject: RE: [PATCH] arm64: dts: renesas: r8a7796: Add CMT device
> > > > nodes
> > > >
> > > > Hi Geert,
> > > >
> > > > Thanks for the feedback. I started testing CMT on latest
> > > > kernel(Linux-next-
> > > > 20190125 and also renesas-dev) and found that it is broken on
> > > > R-Car M3-W device.
> > > >
> > > > On further investigation the patch ("
> > > > 8234f6734c5d74ac794e5517437f51c57d65f865" PM-runtime: Switch
> > > > autosuspend over to using hrtimers) is causing the issue.
> > > >
> > > > During clock source switching, It calls the function "sh_cmt_enable"
> > > > which calls " pm_runtime_get_sync(&ch->cmt->pdev->dev);" and
> > > > after that console freezes.
> > > >
> > > > Sergei: Have you noticed this issue on R-Car V3M and V3H boards
> > > > with latest kernel?
> > > >
> > > > Regards,
> > > > Biju
> > > >
> > > > > -----Original Message-----
> > > > > From: linux-renesas-soc-owner@xxxxxxxxxxxxxxx
> > > > > <linux-renesas-soc- owner@xxxxxxxxxxxxxxx> On Behalf Of Geert
> > > > > Uytterhoeven
> > > > > Sent: 24 January 2019 10:16
> > > > > To: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > > > > Cc: Rob Herring <robh+dt@xxxxxxxxxx>; Mark Rutland
> > > > > <mark.rutland@xxxxxxx>; Simon Horman <horms@xxxxxxxxxxxx>;
> > > > Magnus Damm
> > > > > <magnus.damm@xxxxxxxxx>; Linux-Renesas <linux-renesas-
> > > > > soc@xxxxxxxxxxxxxxx>; open list:OPEN FIRMWARE AND FLATTENED
> > DEVICE
> > > > > TREE BINDINGS <devicetree@xxxxxxxxxxxxxxx>; Geert Uytterhoeven
> > > > > <geert+renesas@xxxxxxxxx>; Chris Paterson
> > > > > <Chris.Paterson2@xxxxxxxxxxx>; Daniel Lezcano
> > > > > <daniel.lezcano@xxxxxxxxxx>; Thomas Gleixner
> > > > > <tglx@xxxxxxxxxxxxx>; John Stultz <john.stultz@xxxxxxxxxx>;
> > > > > Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>; Samuel Holland
> > > > <samuel@xxxxxxxxxxxx>
> > > > > Subject: Re: [PATCH] arm64: dts: renesas: r8a7796: Add CMT
> > > > > device nodes
> > > > >
> > > > > Hi Biju,
> > > > >
> > > > > On Fri, Oct 26, 2018 at 10:32 AM Biju Das
> > > > > <biju.das@xxxxxxxxxxxxxx>
> > > > wrote:
> > > > > > This patch adds CMT{0|1|2|3} device nodes for r8a7796 SoC.
> > > > > >
> > > > > > Signed-off-by: Biju Das <biju.das@xxxxxxxxxxxxxx>
> > > > > > ---
> > > > > > This patch is tested against renesas-dev
> > > > > >
> > > > > > I have executed on inconsistency-check, nanosleep and
> > > > > > clocksource_switch selftests on this arm64 SoC. The
> > > > > > inconsistency-check and nanosleep tests are working fine.The
> > > > > > clocksource_switch asynchronous test is failing due to
> > > > > > inconsistency-check
> > > > > failure on "arch_sys_counter".
> > > > > >
> > > > > > But if i skip the clocksource_switching of "arch_sys_counter",
> > > > > > the asynchronous test is passing for CMT0/1/2/3 timer.
> > > > > >
> > > > > > Has any one noticed this issue?
> > > > >
> > > > > clockevents/next now has commit 7cd6dca3600d8d71
> > > > > ("clocksource/drivers/arch_timer: Workaround for Allwinner A64
> > > > > timer instability"). Perhaps this is related, and the same test
> > > > > program may indicate similar issues?
> > > > >
> > > > > See also https://lore.kernel.org/lkml/20190113021719.46457-2-
> > > > > samuel@xxxxxxxxxxxx/
> > > > >
> > > > > Gr{oetje,eeting}s,
> > > > >
> > > > > Geert
> > > > >
> > > > > --
> > > > > Geert Uytterhoeven -- There's lots of Linux beyond ia32 --
> > > > > geert@linux- m68k.org
> > > > >
> > > > > In personal conversations with technical people, I call myself a
> > > > > hacker. But when I'm talking to journalists I just say
> > > > > "programmer" or
> > > > something like that.
> > > > > -- Linus Torvalds
> > >
> > >
> > >
> > > Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne
> > End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under
> > Registered No. 04586709.
Renesas Electronics Europe Ltd, Dukes Meadow, Millboard Road, Bourne End, Buckinghamshire, SL8 5FH, UK. Registered in England & Wales under Registered No. 04586709.
