[Intel-gfx] [PATCH] drm/i915: Prefault before locking pages in shmem_pwrite
chris at chris-wilson.co.uk
Tue Apr 2 13:07:56 UTC 2019
Quoting Chris Wilson (2019-04-02 13:54:11)
> Quoting Matthew Auld (2019-04-02 13:39:20)
> > On Mon, 1 Apr 2019 at 14:39, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > >
> > > If the user passes in a pointer to a GGTT mmaping of the same buffer
> > > being written to, we can hit a deadlock in acquiring the shmemfs page
> > > (once as the write destination and then as the read source).
> > And also shmem_fault, so cpu mmaping?
> Possibly if I reorder the test to not deadlock on the mmap_gtt first :)
> Let's find out!
Very similar stack trace, as one would expect:
[<0>] i915_gem_object_pwrite_gtt+0xf0/0x160 [i915]
[<0>] i915_gem_pwrite_ioctl+0x145/0x4b0 [i915]
just ending shmem_fault as predicted.
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