Killing context before taking ctx->mutex fixes a hang in
gem_ctx_persistence.close-replace-race, where lut_close
takes obj->resv.lock which is already held by execbuf,
causing a stalling indefinitely.
[ 1904.342847] 2 locks held by gem_ctx_persist/11520:
[ 1904.342849] #0: ffff8882188e4968 (&ctx->mutex){+.+.}-{3:3}, at: context_close+0xe6/0x850 [i915]
[ 1904.342941] #1: ffff88821c58a5a8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: lut_close+0x2c2/0xba0 [i915]
[ 1904.343033] 3 locks held by gem_ctx_persist/11521:
[ 1904.343035] #0: ffffc900008ff938 (reservation_ww_class_acquire){+.+.}-{0:0}, at: i915_gem_do_execbuffer+0x103d/0x54c0 [i915]
[ 1904.343157] #1: ffff88821c58a5a8 (reservation_ww_class_mutex){+.+.}-{3:3}, at: eb_validate_vmas+0x602/0x2010 [i915]
[ 1904.343267] #2: ffff88820afd9200 (&vm->mutex/1){+.+.}-{3:3}, at: i915_vma_pin_ww+0x335/0x2300 [i915]
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 24 ++++++++++-----------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index b9d38e8edb5b..3c89150f7262 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -623,6 +623,18 @@ static void context_close(struct i915_gem_context *ctx)
i915_gem_context_set_closed(ctx);
mutex_unlock(&ctx->engines_mutex);
+ /*
+ * If the user has disabled hangchecking, we can not be sure that
+ * the batches will ever complete after the context is closed,
+ * keeping the context and all resources pinned forever. So in this
+ * case we opt to forcibly kill off all remaining requests on
+ * context close.
+ */
+ if (!i915_gem_context_is_persistent(ctx) ||
+ !i915_modparams.enable_hangcheck)
+ kill_context(ctx);
+
+
mutex_lock(&ctx->mutex);
set_closed_name(ctx);
@@ -641,18 +653,6 @@ static void context_close(struct i915_gem_context *ctx)
lut_close(ctx);
mutex_unlock(&ctx->mutex);
-
- /*
- * If the user has disabled hangchecking, we can not be sure that
- * the batches will ever complete after the context is closed,
- * keeping the context and all resources pinned forever. So in this
- * case we opt to forcibly kill off all remaining requests on
- * context close.
- */
- if (!i915_gem_context_is_persistent(ctx) ||
- !i915_modparams.enable_hangcheck)
- kill_context(ctx);
-
i915_gem_context_put(ctx);
}
--
2.27.0
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