From c071ab8c20748873183d5f210aa105d6a3e2d56a Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 27 Oct 2020 18:47:59 +0000 Subject: [PATCH] drm/i915/gem: Avoid synchronous binds deep within locks On bxt, we require a VT'd w/a to serialise all GGTT updates with memory transfers, and use stop_machine() for this purpose. stop_machine() is a global serialisation barrier and so dangerous to use from within critical sections, as the stop_machine() will wait for all cpus to enter the stop_machine callback, and those cpus may be waiting for the critical section already held. Fixes: d7085b0faac8 ("drm/i915/gem: Poison stolen pages before use") Signed-off-by: Chris Wilson Cc: Mika Kuoppala Reviewed-by: Mika Kuoppala Link: https://patchwork.freedesktop.org/patch/msgid/20201027184759.29888-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c index 78f64a2724e2a..69a37a1fcff2d 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c @@ -505,6 +505,9 @@ static void dbg_poison(struct i915_ggtt *ggtt, if (!drm_mm_node_allocated(&ggtt->error_capture)) return; + if (ggtt->vm.bind_async_flags & I915_VMA_GLOBAL_BIND) + return; /* beware stop_machine() inversion */ + GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE)); mutex_lock(&ggtt->error_mutex); -- 2.39.5