From: Chris Wilson <chris@chris-wilson.co.uk>
To: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
intel-gfx@lists.freedesktop.org
Subject: Re: [Intel-gfx] [PATCH 2/6] drm/i915/gem: Avoid gem_context->mutex for simple vma lookup
Date: Thu, 19 Mar 2020 14:52:21 +0000 [thread overview]
Message-ID: <158462954105.6873.17855848411603572916@build.alporthouse.com> (raw)
In-Reply-To: <99ee9e55-1aeb-5cb7-4378-a62f671f4811@linux.intel.com>
Quoting Tvrtko Ursulin (2020-03-19 14:20:04)
>
> On 19/03/2020 09:19, Chris Wilson wrote:
> > +static struct i915_vma *eb_lookup_vma(struct i915_execbuffer *eb, u32 handle)
> > +{
> > + do {
> > + struct drm_i915_gem_object *obj;
> > struct i915_vma *vma;
> > + int err;
> >
> > - vma = radix_tree_lookup(handles_vma, handle);
> > + rcu_read_lock();
> > + vma = radix_tree_lookup(&eb->gem_context->handles_vma, handle);
>
> radix_tree_lookup is documented to be RCU safe okay. How about freeing
> VMAs - is that done after a RCU grace period?
As we are still stuck with the horrible i915_vma.kref semantics (yes, I
know I'm supposed to be fixing that), there are 3 paths which may
destroy i915_vma: the object (RCU safe), the vm (RCU safe) and
i915_vma_parked, not safe in any way shape or form.
A quick and dirty solution would be to move i915_vma_parked behind an
rcu work.
-Chris
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next prev parent reply other threads:[~2020-03-19 14:52 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 9:19 [Intel-gfx] [PATCH 1/6] drm/i915: Prefer '%ps' for printing function symbol names Chris Wilson
2020-03-19 9:19 ` [Intel-gfx] [PATCH 2/6] drm/i915/gem: Avoid gem_context->mutex for simple vma lookup Chris Wilson
2020-03-19 14:20 ` Tvrtko Ursulin
2020-03-19 14:52 ` Chris Wilson [this message]
2020-03-19 16:02 ` Chris Wilson
2020-03-19 9:19 ` [Intel-gfx] [PATCH 3/6] drm/i915/execlists: Force single submission for sentinels Chris Wilson
2020-03-19 14:31 ` Tvrtko Ursulin
2020-03-19 15:02 ` Chris Wilson
2020-03-19 15:11 ` Tvrtko Ursulin
2020-03-19 15:21 ` Chris Wilson
2020-03-19 15:31 ` Chris Wilson
2020-03-19 16:58 ` Chris Wilson
2020-03-19 9:19 ` [Intel-gfx] [PATCH 4/6] drm/i915/gem: Wait until the context is finally retired before releasing engines Chris Wilson
2020-03-19 14:36 ` Tvrtko Ursulin
2020-03-19 9:19 ` [Intel-gfx] [PATCH 5/6] drm/i915: Use explicit flag to mark unreachable intel_context Chris Wilson
2020-03-19 9:19 ` [Intel-gfx] [PATCH 6/6] drm/i915/gt: Cancel a hung context if already closed Chris Wilson
2020-03-19 14:40 ` Tvrtko Ursulin
2020-03-19 14:43 ` Tvrtko Ursulin
2020-03-19 10:20 ` [Intel-gfx] ✓ Fi.CI.BAT: success for series starting with [1/6] drm/i915: Prefer '%ps' for printing function symbol names Patchwork
2020-03-19 11:39 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2020-03-19 13:53 ` [Intel-gfx] [PATCH 1/6] " Tvrtko Ursulin
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