On Fri, May 13, 2016 at 7:22 AM, dann frazier
<email address hidden> wrote:
> I used ftrace to do some duration measuring of the timer function
> fb_flashcursor(). I noticed several places where this timer takes around
> 98 ms to complete. This time seems to be due to multiple calls to
> __memcpy_toio() in ast_dirty_update():
>
>         for (i = y; i <= y2; i++) {
>                 /* assume equal stride for now */
>                 src_offset = dst_offset = i * afbdev->afb.base.pitches[0] + (x * bpp);
>                 memcpy_toio(bo->kmap.virtual + src_offset, afbdev->sysram + src_offset, (x2 - x + 1) * bpp);
>
>
> My theory is that this is causing mod_timer() to block on the other CPU, resulting in the soft lockup.
>
> Also - I built a custom d-i using pristine 4.6-rc7, and I am able to
> easily reproduce this. I think the next step here is to report this to
> upstream.

Hi Dann,

Andrew asked me to take a look at the issue, and from my tracing,
most of times, the cpu 'hangs' in the following line of code:

__mod_timer():
....
out_unlock:
     spin_unlock_irqrestore(&base->lock, flags);

If I added two trace points around the above line, most of times only
the trace point before the line is dumped, and the one after the line
can't dumped.

Thanks,

>
> --
> You received this bug notification because you are subscribed to linux
> in Ubuntu.
> https://bugs.launchpad.net/bugs/1574814
>
> Title:
>   ThunderX: soft lockup in cursor_timer_handler() Edit
>
> Status in linux package in Ubuntu:
>   Confirmed
>
> Bug description:
>   I booted a Cavium ThunderX crb1s 2.0 system using the netboot mini iso via virtual media:
>     http://ports.ubuntu.com/ubuntu-ports/dists/xenial/main/installer-arm64/20101020ubuntu451/images/netboot/mini.iso
>
>   During boot I observed the following lockup on the serial console:
>
>   [ 28.128327] usb 1-1.1: reset high-speed USB device number 3 using xhci_hcd
>   [ 84.912299] NMI watchdog: BUG: soft lockup - CPU#14 stuck for 23s! [swapper/14:0]
>   [ 84.922718] Modules linked in: hid_generic(E) usbhid(E) hid(E) usb_storage(E) mdio_thunder(E) nicvf(E) ast(E) i2c_algo_bit(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) sysimgblt(E) fb_sys_fops(E) ttm(E) drm(E) nicpf(E) thunder_bgx(E) mdio_cavium(E)
>   [ 84.922749]
>   [ 84.922754] CPU: 14 PID: 0 Comm: swapper/14 Tainted: G E 4.4.0-21-generic #37-Ubuntu
>   [ 84.922757] Hardware name: Cavium ThunderX CN88XX board (DT)
>   [ 84.922761] task: ffff801f6c9d4100 ti: ffff801f6c9e8000 task.ti: ffff801f6c9e8000
>   [ 84.922771] PC is at cursor_timer_handler+0x30/0x58
>   [ 84.922775] LR is at cursor_timer_handler+0x30/0x58
>   [ 84.922778] pc : [<ffff8000004ec4f0>] lr : [<ffff8000004ec4f0>] pstate: 00400145
>   [ 84.922781] sp : ffff801f6c9ebc20
>   [ 84.922784] x29: ffff801f6c9ebc20 x28: ffff8000f94398d8
>   [ 84.922789] x27: ffff801f6c9ebd00 x26: ffff801f7b3bebb8
>   [ 84.922793] x25: ffff801f6c9e8000 x24: ffff800000e5ec00
>   [ 84.922798] x23: ffff801f667d9800 x22: ffff8000004ec4c0
>   [ 84.922802] x21: 0000000000000100 x20: ffff8000f94398d8
>   [ 84.922807] x19: ffff8000f9439800 x18: 0000ffffc76a5358
>   [ 84.922811] x17: 0000ffff97bbd2a8 x16: ffff8000002a5040
>   [ 84.922816] x15: 000000003e4cf1e0 x14: 0000000000000008
>   [ 84.922820] x13: 0000000000000000 x12: 003d090000000000
>   [ 84.922824] x11: 00000000003d0900 x10: ffff80000090f200
>   [ 84.922829] x9 : 00003d0900000000 x8 : 000000000000000e
>   [ 84.922833] x7 : ffff801f7b3c5008 x6 : 00000000ffffffff
>   [ 84.922837] x5 : 0000000000000000 x4 : 0000000000000001
>   [ 84.922842] x3 : 0000000000000000 x2 : ffff801f6c899e05
>   [ 84.922846] x1 : ffff801f667d99e0 x0 : 0000000000000000
>   [ 84.922850]
>   [ 101.008387] usb 1-1.1: reset high-speed USB device number 3 using xhci_hcd
>   [ 101.180375] usb 1-1.1: reset high-speed USB device number 3 using xhci_hcd
>   [ 101.342677] random: nonblocking pool is initialized
>
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