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
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