lkml.org 
[lkml]   [2013]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: hrtimer: one more expiry time overflow check in hrtimer_interrupt


On 06/11/2013 03:41 AM, Shinya Kuribayashi wrote:
> When executing a date command to set the system date and time to a few
> seconds before the 2038 problem expiration time, we got a WARN_ON_ONCE()
> like this:
>
> root@renesas:~# date -s "2038-1-19 3:14:00"
> Tue Jan 19 03:14:00 GMT 2038
> (then wait for 7-8 seconds)
> root@renesas:~# [ 27.662658] ------------[ cut here ]------------
> [ 27.667297] WARNING: at kernel/time/clockevents.c:209 clockevents_program_event+0x3c/0x138()
> [ 27.675720] Modules linked in:
> [ 27.678802] [<c00130ec>] (unwind_backtrace+0x0/0xe0) from [<c001f4d8>] (warn_slowpath_common+0x4c/0x64)
> [ 27.688201] [<c001f4d8>] (warn_slowpath_common+0x4c/0x64) from [<c001f508>] (warn_slowpath_null+0x18/0x1c)
> [ 27.697845] [<c001f508>] (warn_slowpath_null+0x18/0x1c) from [<c00549bc>] (clockevents_program_event+0x3c/0x138)
> [ 27.708007] [<c00549bc>] (clockevents_program_event+0x3c/0x138) from [<c005510c>] (tick_program_event+0x2c/0x34)
> [ 27.718170] [<c005510c>] (tick_program_event+0x2c/0x34) from [<c003fa98>] (hrtimer_interrupt+0x268/0x2a8)
> [ 27.727752] [<c003fa98>] (hrtimer_interrupt+0x268/0x2a8) from [<c00180c8>] (cmt_timer_interrupt+0x2c/0x34)
> [ 27.737396] [<c00180c8>] (cmt_timer_interrupt+0x2c/0x34) from [<c0066748>] (handle_irq_event_percpu+0xb0/0x2a8)
> [ 27.747467] [<c0066748>] (handle_irq_event_percpu+0xb0/0x2a8) from [<c0066998>] (handle_irq_event+0x58/0x74)
> [ 27.757293] [<c0066998>] (handle_irq_event+0x58/0x74) from [<c0068f24>] (handle_fasteoi_irq+0xc0/0x148)
> [ 27.766662] [<c0068f24>] (handle_fasteoi_irq+0xc0/0x148) from [<c0066014>] (generic_handle_irq+0x20/0x30)
> [ 27.776245] [<c0066014>] (generic_handle_irq+0x20/0x30) from [<c000ef54>] (handle_IRQ+0x60/0x84)
> [ 27.785003] [<c000ef54>] (handle_IRQ+0x60/0x84) from [<c0009334>] (gic_handle_irq+0x34/0x4c)
> [ 27.793426] [<c0009334>] (gic_handle_irq+0x34/0x4c) from [<c000e2c0>] (__irq_svc+0x40/0x70)
> [ 27.801788] Exception stack(0xc04aff68 to 0xc04affb0)
> [ 27.806823] ff60: 00000000 f0100000 00000001 00000000 c04ae000 c04ec388
> [ 27.815002] ff80: c04b604c c0840d80 40004059 412fc093 00000000 00000000 c04ce140 c04affb0
> [ 27.823150] ffa0: c000f064 c000f068 60000013 ffffffff
> [ 27.828216] [<c000e2c0>] (__irq_svc+0x40/0x70) from [<c000f068>] (default_idle+0x24/0x2c)
> [ 27.836395] [<c000f068>] (default_idle+0x24/0x2c) from [<c000f338>] (cpu_idle+0x74/0xc8)
> [ 27.844451] [<c000f338>] (cpu_idle+0x74/0xc8) from [<c048c6d4>] (start_kernel+0x248/0x288)
> [ 27.852722] ---[ end trace 9d8ad385bde80fd3 ]---


> [ 27.857330] hrtimer: interrupt took 0 ns

^^^ see below ...

>
> This is triggered with our v3.4-based custom ARM kernel, but we
> confirmed that v3.10-rc can still have the same problem.
>
> I found a similar issue fixed in v3.9 by Prarit Bhargava in commit
> 8f294b5a13 (hrtimer: Add expiry time overflow check in hrtimer_interrupt,
> 2013-04-08). It tried to resolve a overflow issue detected around 1970
> + 100 seconds.
>
> On the other hand, we have another call site of tick_program_event() at
> the bottom of hrtimer_interrupt(). The warning this time is triggered
> there, so we need to apply the same fix to it.
>
> Reported-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
> Signed-off-by: Shinya Kuribayashi <shinya.kuribayashi.px@renesas.com>
> ---
>
> Hi Prarit-san and John-san,
>
> http://git.kernel.org/linus/8f294b5a139ee4b75e890ad5b443c93d1e558a8b
> hrtimer: Add expiry time overflow check in hrtimer_interrupt
>
> I tried to fix the other case of overflow issues in hrtimer_interrupt(),
> but not sure it should be worked around like this in the first place.
>
> Any comments are appreciated, thanks in advance.
>
> diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
> index cdd5607..a42d712 100644
> --- a/kernel/hrtimer.c
> +++ b/kernel/hrtimer.c
> @@ -1368,6 +1370,8 @@ retry:
> expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
> else
> expires_next = ktime_add(now, delta);
> + if (expires_next.tv64 < 0)
> + expires_next.tv64 = KTIME_MAX;

Even with this change you will still see the warning below if delta = 0.

> tick_program_event(expires_next, 1);
> printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
> ktime_to_ns(delta));

So I'm not sure that this is the correct thing to do.

Is this reproducible on any ARM system? I'll grab an x86_64 box and give it a
shot there too. Can you dump the values of now, delta, and expires_next when
the printk_once triggers?

P.


\
 
 \ /
  Last update: 2013-06-12 15:01    [W:0.086 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site