When iterating over the bound list, we expect all objects there to have
their pages pinned (by the bound VMA). So only report those objects with
additional pin count on their pages as "pinned". These should be those
objects used for display and hardware access.
Reported-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Akash Goel <akash.goel@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461150592-27818-1-git-send-email-chris@chris-wilson.co.uk

When called because we have run out of vmap address space, we only need
to recover objects that have vmappings and not all.

v2: Start using is_vmalloc_addr()
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1460113874-17366-5-git-send-email-chris@chris-wilson.co.ukReviewed-by: NTvrtko Ursulin <tvrtko.ursulin@linux.intel.com>

Both the oom and vmap notifier callbacks have a loop to acquire the
struct_mutex and set the device as uninterruptible, within a certain
time. Refactor the common code into a pair of functions.
Suggested-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459848145-24042-1-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

If the core runs out of vmap address space, it will call a notifier in
case any driver can reap some of its vmaps. As i915.ko is possibily
holding onto vmap address space that could be recovered, hook into the
notifier chain and try and reap objects holding onto vmaps.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Roman Pen <r.peniaev@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kahola <mika.kahola@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459777603-23618-4-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Since we only attempt to purge an object if can_release_pages() report
true, we should also only add it to the count of potential recoverable
pages when can_release_pages() is true.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Akash Goel <akash.goel@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1459777603-23618-2-git-send-email-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com>

Elsewhere we have adopted the convention of using '_link' to denote
elements in the list (and '_list' for the actual list_head itself), and
that the name should indicate which list the link belongs to (and
preferrably not just where the link is being stored).

s/vma_link/obj_link/ (we iterate over obj->vma_list)
s/mm_list/vm_link/ (we iterate over vm->[in]active_list)
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: NTvrtko Ursulin <tvrtko.ursulin@intel.com>

Factor out the common GEM shrinker clean-up code and call the shrinker
init function from the same function from where the corresponding
shrinker clean-up function is called. Also add sanity checking to the
shrinker and OOM registration calls.
Signed-off-by: NImre Deak <imre.deak@intel.com>
Reviewed-by: NDavid Weinehall <david.weinehall@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1453209992-25995-4-git-send-email-imre.deak@intel.com

If the system has no available swap pages, we cannot make forward
progress in the shrinker by releasing active pages, only by releasing
purgeable pages which are immediately reaped. Take total_swap_pages into
account when counting up available objects to be shrunk and subsequently
shrinking them. By doing so, we avoid unbinding objects that cannot be
shrunk and so wasting CPU cycles flushing those objects from the GPU to
the system and then immediately back again (as they will more than
likely be reused shortly after).

Based on a patch by Akash Goel.

v2: frontswap registers extra swap pages available for the system, so it
is already include in the count of available swap pages.

v3: Use get_nr_swap_pages() to query the currently available amount of
swap space. This should also stop us from shrinking the GPU buffers if
we ever run out of swap space. Though at that point, we would expect the
oom-notifier to be running and failing miserably...
Reported-by: NAkash Goel <akash.goel@intel.com>
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: linux-mm@kvack.org
Cc: Akash Goel <akash.goel@intel.com>
Cc: sourab.gupta@intel.com
Link: http://patchwork.freedesktop.org/patch/msgid/1449244734-25733-2-git-send-email-chris@chris-wilson.co.ukAcked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I've botched this in

commit eb0b44ad
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Mar 18 14:47:59 2015 +0100

    drm/i915: kerneldoc for i915_gem_shrinker.c

so let's fix it.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>

Exclude active GPU pages from the purview of the background shrinker
(kswapd), as these cause uncontrollable GPU stalls. Given that the
shrinker is rerun until the freelists are satisfied, we should have
opportunity in subsequent passes to recover the pages once idle. If the
machine does run out of memory entirely, we have the forced idling in the
oom-notifier as a means of releasing all the pages we can before an oom
is prematurely executed.

Note that this relies upon an up-front retire_requests to keep the
inactive list in shape, which was added in a previous patch, mostly as
execlist ctx pinning band-aids.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
[danvet: Add note about retire_requests.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

We can forgo an evict-everything here as the shrinker operation itself
will unbind any vma as required. If we explicitly idle the GPU through a
switch to the default context, we not only create a request in an
illegal context (e.g. whilst shrinking during execbuf with a request
already allocated), but switching to the default context will not free
up the memory backing the active contexts - unless in the unlikely
situation that context had already been closed (and just kept arrive by
being the current context). The saving is near zero and the danger real.

To compensate for the loss of the forced retire, add a couple of
retire-requests to i915_gem_shirnk() - this should help free up any
transitive cache from the requests.

Note that the second retire_requests is for the benefit of the
hand-rolled execlist ctx active tracking: We need to manually kick
requests to get those unpinned again. Once that's fixed we can try to
remove this again.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Add summary of why we need a pile of retire_requests.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Often it is very useful to know why we suddenly purge vast tracts of
memory and surprisingly up until now we didn't even have a tracepoint
for when we shrink our memory.

Note that there are slab_start/end tracepoints already, but those
don't cover the internal recursion when we directly call into our
shrinker code. Hence a separate tracepoint seems justified. Also note
that we don't really need a separate tracepoint for the actual amount
of pages freed since we already have an unbind tracpoint for that.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
[danvet: Add a note that there's also slab_start/end and why they're
insufficient.]
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

As the shrinker_control now passes us unsigned long targets, update our
shrinker functions to match.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

I've botched this, so let's fix it.

Botched in

commit eb0b44ad
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed Mar 18 14:47:59 2015 +0100

    drm/i915: kerneldoc for i915_gem_shrinker.c

v2: Be a good citizen^Wmaintainer and add the proper commit citation.
Noticed by Jani.
Reviewed-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>

When looking for viable candidates to shrink, we only want objects that
are not pinned. However to do so we performed a double iteration over
the vma in the objects, first looking for the pin-count, then looking
for allocations. We can do both at once and be slightly more explicit in
our validity test.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

And remove one bogus * from i915_gem_gtt.c since that's not a
kerneldoc there.

v2: Review from Chris:
- Clarify memory space to better distinguish from address space.
- Add note that shrink doesn't guarantee the freed memory and that
  users must fall back to shrink_all.
- Explain how pinning ties in with eviction/shrinker.

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

Two code changes:
- Extract i915_gem_shrinker_init.
- Inline i915_gem_object_is_purgeable since we open-code it everywhere
  else too.

This already has the benefit of pulling all the shrinker code
together, next patch adds a bit of kerneldoc.
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>