Commit e339c6d6 authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Rodrigo Vivi

drm/i915: Retry gtt fault when out of fence registers

If we can't find a free fence register to handle a fault in the GMADR
range just return VM_FAULT_NOPAGE without populating the PTE so that
userspace will retry the access and trigger another fault. Eventually
we should find a free fence and the fault will get properly handled.

A further improvement idea might be to reserve a fence (or one per CPU?)
for the express purpose of handling faults without having to retry. But
that would require some additional work.

Looks like this may have gotten broken originally by
commit 39965b37 ("drm/i915: don't trash the gtt when running out of fences")
as that changed the errno to -EDEADLK which wasn't handle by the gtt
fault code either. But later in commit 2feeb528 ("drm/i915/gt: Fix
-EDEADLK handling regression") I changed it again to -ENOBUFS as -EDEADLK
was now getting used for the ww mutex dance. So this fix only makes
sense after that last commit.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/9479
Fixes: 2feeb528 ("drm/i915/gt: Fix -EDEADLK handling regression")
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231012132801.16292-1-ville.syrjala@linux.intel.comReviewed-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
(cherry picked from commit 7f403caa)
Signed-off-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
parent 5e4c16fe
......@@ -235,6 +235,7 @@ static vm_fault_t i915_error_to_vmf_fault(int err)
case 0:
case -EAGAIN:
case -ENOSPC: /* transient failure to evict? */
case -ENOBUFS: /* temporarily out of fences? */
case -ERESTARTSYS:
case -EINTR:
case -EBUSY:
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment