[Bug 104786] [CI] [KBL-only] igt at drv_selftest@live_hangcheck - dmesg-fail - kernel stack overflow

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=104786

Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #8 from Chris Wilson <chris at chris-wilson.co.uk> ---
commit 01b8fdc5222007bdfc905941173f82576898a7f7
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Mon Feb 5 15:24:31 2018 +0000

    drm/i915: Skip post-reset request emission if the engine is not idle

    Since commit 7b6da818d86f ("drm/i915: Restore the kernel context after a
    GPU reset on an idle engine") we submit a request following the engine
    reset. The intent is that we don't submit a request if the engine is
    busy (as it will restart active by itself) but we only checked to see if
    there were remaining requests in flight on the hardware and skipped
    checking to see if there were any ready requests that would be
    immediately submitted on restart (the same time as our new request would
    be). Having convinced the engine to appear idle in the previous patch,
    we can use intel_engine_is_idle() as a better test to only submit a new
    request if there are no pending requests.

    As it happens, this is tripping up igt/drv_selftest/live_hangcheck in CI
    as we overfill the kernel_context ringbuffer trigger an infinite
    recursion from within the reset.

    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=104786
    References: 7b6da818d86f ("drm/i915: Restore the kernel context after a GPU
reset on an idle engine")
    Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
    Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
    Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Cc: Michel Thierry <michel.thierry at intel.com>
    Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
    Link:
https://patchwork.freedesktop.org/patch/msgid/20180205152431.12163-4-chris@chris-wilson.co.uk

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