On pe, 2017-06-09 at 12:03 +0100, Chris Wilson wrote:
> I tried __GFP_NORETRY in the belief that __GFP_RECLAIM was effective. It
> struggles with handling reclaim of our dirty buffers and relies on
> reclaim via kswapd. As a result, a single pass of direct reclaim is
> unreliable when i915 occupies the majority of available memory, and the
> only means of effectively waiting on kswapd to amke progress is by not
> setting the __GFP_NORETRY flag and lopping. That leaves us with the
> dilemma of invoking the oomkiller instead of propagating the allocation
> failure back to userspace where it can be handled more gracefully (one
> hopes). In the future we may have __GFP_MAYFAIL to allow repeats up until
> we genuinely run out of memory and the oomkiller would have been invoked.
> Until then, let the oomkiller wreck havoc.
>
> v2: Stop playing with side-effects of gfp flags and await __GFP_MAYFAIL
> v3: Update comments that direct reclaim only appears to be ignoring our
> dirty buffers!
>
> Fixes: 24f8e00a8a2e ("drm/i915: Prefer to report ENOMEM rather than incur the oom for gfx allocations")
> Testcase: igt/gem_tiled_swapping
> Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Regards, Joonas
--
Joonas Lahtinen
Open Source Technology Center
Intel Corporation
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