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win32: Leak of TimerQueueTimers #170

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Rondom opened this issue Jul 1, 2016 · 1 comment
Open

win32: Leak of TimerQueueTimers #170

Rondom opened this issue Jul 1, 2016 · 1 comment

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@Rondom
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Rondom commented Jul 1, 2016

On Windows, everytime a new TimerQueueTimers is scheduled by nt-host.c:timer_set_oneshot, a HANDLE is allocated for that timer.

Currently those timer-handles are only freed when the whole TimerQueue is freed using DeleteTimerQueueEx in nt-host.c:timer_free. This is problematic because we will accumulate those handles over the runtime of the process and crash on Win32-x86 when the process size has reached 2 GB ;-)

These handles can already be freed beforehand, by calling DeleteTimerQueueTimer. I implemented a quick (hacky) fix by freeing the previously scheduled timer using DeleteTimerQueueTimer in timer_set_oneshot, but I do not think this is a good solution and might even be prone to race conditions.

Before I waste a lot of time on this I am wondering how to fix this "properly". Allocating (and with the fix also freeing ;-) ) the handles is quite some overhead. Would it be possible to set up a periodic timer instead? Or could we somehow reuse handles using ChangeTimerQueueTimer?

I am still learning, and I would love to hear your thoughts :-)

@ghost
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ghost commented Aug 19, 2016

Unfortunately we can't use a periodic timer because the Linux timer tick is dynamic when entering idle.

I think the fix with freeing the previously scheduled timer its good. We can't have race conditions since the LKL is single threaded at the moment and the only calls to timer_set_oneshot comes from LKL threads.

thehajime pushed a commit to libos-nuse/lkl-linux that referenced this issue Feb 23, 2017
The goal of the WARN was to catch when we are still actively using the
fence as we go into the runtime suspend. However, the reg->pin_count is
too coarse as it does not distinguish between exclusive ownership of the
fence register from activity.

I've not improved on the WARN, nor have we captured this WARN in an
exact igt, but it is showing up regularly in the wild:

[ 1915.935332] WARNING: CPU: 1 PID: 10861 at drivers/gpu/drm/i915/i915_gem.c:2022 i915_gem_runtime_suspend+0x116/0x130 [i915]
[ 1915.935383] WARN_ON(reg->pin_count)[ 1915.935399] Modules linked in:
 snd_hda_intel i915 drm_kms_helper vgem netconsole scsi_transport_iscsi fuse vfat fat x86_pkg_temp_thermal coretemp intel_cstate intel_uncore snd_hda_codec_hdmi snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd mei_me mei serio_raw intel_rapl_perf intel_pch_thermal soundcore wmi acpi_pad i2c_algo_bit syscopyarea sysfillrect sysimgblt fb_sys_fops drm r8169 mii video [last unloaded: drm_kms_helper]
[ 1915.935785] CPU: 1 PID: 10861 Comm: kworker/1:0 Tainted: G     U  W       4.9.0-rc5+ lkl#170
[ 1915.935799] Hardware name: LENOVO 80MX/Lenovo E31-80, BIOS DCCN34WW(V2.03) 12/01/2015
[ 1915.935822] Workqueue: pm pm_runtime_work
[ 1915.935845]  ffffc900044fbbf0 ffffffffac3220bc ffffc900044fbc40 0000000000000000
[ 1915.935890]  ffffc900044fbc30 ffffffffac059bcb 000007e6044fbc60 ffff8801626e3198
[ 1915.935937]  ffff8801626e0000 0000000000000002 ffffffffc05e5d4e 0000000000000000
[ 1915.935985] Call Trace:
[ 1915.936013]  [<ffffffffac3220bc>] dump_stack+0x4f/0x73
[ 1915.936038]  [<ffffffffac059bcb>] __warn+0xcb/0xf0
[ 1915.936060]  [<ffffffffac059c4f>] warn_slowpath_fmt+0x5f/0x80
[ 1915.936158]  [<ffffffffc052d916>] i915_gem_runtime_suspend+0x116/0x130 [i915]
[ 1915.936251]  [<ffffffffc04f1c74>] intel_runtime_suspend+0x64/0x280 [i915]
[ 1915.936277]  [<ffffffffac0926f1>] ? dequeue_entity+0x241/0xbc0
[ 1915.936298]  [<ffffffffac36bb85>] pci_pm_runtime_suspend+0x55/0x180
[ 1915.936317]  [<ffffffffac36bb30>] ? pci_pm_runtime_resume+0xa0/0xa0
[ 1915.936339]  [<ffffffffac4514e2>] __rpm_callback+0x32/0x70
[ 1915.936356]  [<ffffffffac451544>] rpm_callback+0x24/0x80
[ 1915.936375]  [<ffffffffac36bb30>] ? pci_pm_runtime_resume+0xa0/0xa0
[ 1915.936392]  [<ffffffffac45222d>] rpm_suspend+0x12d/0x680
[ 1915.936415]  [<ffffffffac69f6d7>] ? _raw_spin_unlock_irq+0x17/0x30
[ 1915.936435]  [<ffffffffac0810b8>] ? finish_task_switch+0x88/0x220
[ 1915.936455]  [<ffffffffac4534bf>] pm_runtime_work+0x6f/0xb0
[ 1915.936477]  [<ffffffffac074353>] process_one_work+0x1f3/0x4d0
[ 1915.936501]  [<ffffffffac074678>] worker_thread+0x48/0x4e0
[ 1915.936523]  [<ffffffffac074630>] ? process_one_work+0x4d0/0x4d0
[ 1915.936542]  [<ffffffffac074630>] ? process_one_work+0x4d0/0x4d0
[ 1915.936559]  [<ffffffffac07a2c9>] kthread+0xd9/0xf0
[ 1915.936580]  [<ffffffffac07a1f0>] ? kthread_park+0x60/0x60
[ 1915.936600]  [<ffffffffac69fe62>] ret_from_fork+0x22/0x30

In the case the register is pinned, it should be present and we will
need to invalidate them to be restored upon resume as we cannot expect
the owner of the pin to call get_fence prior to use after resume.

Fixes: 7c108fd ("drm/i915: Move fence cancellation to runtime suspend")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98804
Reported-by: Lionel Landwerlin <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Imre Deak <[email protected]>
Cc: Jani Nikula <[email protected]>
Cc: <[email protected]> # v4.10-rc1+
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Joonas Lahtinen <[email protected]>
(cherry picked from commit e0ec3ec)
Signed-off-by: Jani Nikula <[email protected]>
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