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drm/i915: Report -EFAULT before pwrite fast path into shmemfs 

When pwriting into shmemfs, the fast path pagecache_write does not
notice when it is writing to beyond the end of the truncated shmemfs
inode. Report -EFAULT directly when we try to use pwrite into the
!I915_MADV_WILLNEED object.

Fixes: 7c55e2c577 ("drm/i915: Use pagecache write to prepopulate shmemfs from pwrite-ioctl")
Testcase: igt/gem_madvise/dontneed-before-pwrite
Signed-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>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171016202732.25459-1-chris@chris-wilson.co.uk
(cherry picked from commit a6d65e451c)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
This commit is contained in:
Chris Wilson 2017-10-16 21:27:32 +01:00 committed by Rodrigo Vivi
parent 038daf5556
commit ca8d782205
1 changed files with 3 additions and 0 deletions
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3
drivers/gpu/drm/i915/i915_gem.c
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@ -2657,6 +2657,9 @@ i915_gem_object_pwrite_gtt(struct drm_i915_gem_object *obj,
if (READ_ONCE(obj->mm.pages))
return -ENODEV;
if (obj->mm.madv != I915_MADV_WILLNEED)
return -EFAULT;
/* Before the pages are instantiated the object is treated as being
* in the CPU domain. The pages will be clflushed as required before
* use, and we can freely write into the pages directly. If userspace