On 1/5/21 4:35 PM, Maarten Lankhorst wrote:
We get a lockdep splat when the reset mutex is held, because it can be
taken from fence_wait. This conflicts with the mmu notifier we have,
because we recurse between reset mutex and mmap lock -> mmu notifier.
Remove this recursion by calling revoke_mmaps before taking the lock.
Hmm. Is the mmap se taken from gt_revoke()?
If so, isn't the real problem that the mmap_sem is taken in the
dma_fence critical path (where the reset code sits)?
/Thomas
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_reset.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
index 9d177297db79..3c0807d9a86e 100644
--- a/drivers/gpu/drm/i915/gt/intel_reset.c
+++ b/drivers/gpu/drm/i915/gt/intel_reset.c
@@ -975,8 +975,6 @@ static int do_reset(struct intel_gt *gt, intel_engine_mask_t stalled_mask)
{
int err, i;
- gt_revoke(gt);
-
err = __intel_gt_reset(gt, ALL_ENGINES);
for (i = 0; err && i < RESET_MAX_RETRIES; i++) {
msleep(10 * (i + 1));
@@ -1031,6 +1029,9 @@ void intel_gt_reset(struct intel_gt *gt,
might_sleep();
GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, >->reset.flags));
+
+ gt_revoke(gt);
+
mutex_lock(>->reset.mutex);
/* Clear any previous failed attempts at recovery. Time to try again. */
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