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Chris Wilson authored
Before we instantiate/pin the backing store for our use, we can prepopulate the shmemfs filp efficiently using a write into the pagecache. We avoid the penalty of instantiating all the pages, important if the user is just writing to a few and never uses the object on the GPU, and using a direct write into shmemfs allows it to avoid the cost of retrieving a page (mostly the clear-before-use, but in theory we could curtail swapin) before it is overwritten. This can be extended later to provide additional specialisation for other backends (other than shmemfs). For now it provides a defense against very large write-only allocations from exhausting all of system memory. v2: Smelling fixes. Fixes: fe115628 ("drm/i915: Implement pwrite without struct-mutex") References: https://bugs.freedesktop.org/show_bug.cgi?id=99107Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Cc: Matthew Auld <matthew.william.auld@gmail.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: <stable@vger.kernel.org> # v4.10+ Reviewed-by:
Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Reviewed-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20170307120338.7277-2-chris@chris-wilson.co.uk
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