drm/i915/gem: Store mmap_offsets in an rbtree rather than a plain list

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Currently we create a new mmap_offset for every call to
mmap_offset_ioctl. This exposes ourselves to an abusive client that may
simply create new mmap_offsets ad infinitum, which will exhaust physical
memory and the virtual address space. In addition to the exhaustion, a
very long linear list of mmap_offsets causes other clients using the
object to incur long list walks -- these long lists can also be
generated by simply having many clients generate their own mmap_offset.

However, we can simply use the drm_vma_node itself to manage the file
association (allow/revoke) dropping our need to keep an mmo per-file.
Then if we keep a small rbtree of per-type mmap_offsets, we can lookup
duplicate requests quickly.

Fixes: cc662126b4 ("drm/i915: Introduce DRM_I915_GEM_MMAP_OFFSET")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Reviewed-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200120104924.4000706-3-chris@chris-wilson.co.uk
(cherry picked from commit 7865559872)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

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Chris Wilson 2020-01-20 10:49:22 +00:00 • committed by Jani Nikula

parent a754012b9f

commit 07ccd6bdaf

3 changed files with 85 additions and 29 deletions

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90

drivers/gpu/drm/i915/gem/i915_gem_mman.c

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18

drivers/gpu/drm/i915/gem/i915_gem_object.c

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6

drivers/gpu/drm/i915/gem/i915_gem_object_types.h

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