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authorJoonas Lahtinen <joonas.lahtinen@linux.intel.com>2017-04-07 13:49:34 +0300
committerJani Nikula <jani.nikula@intel.com>2017-04-11 13:25:18 +0300
commitc053b5a506d3afc038c485a86e3d461f6c7fb207 (patch)
tree47598d411d0ab808276ed88d8990b87cf94c32f8 /drivers
parent63987bfebd8869e00b34e2bdd12e59d71909bec0 (diff)
drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
Only call synchronize_rcu_expedited after unlocking struct_mutex to avoid deadlock because the workqueues depend on struct_mutex. >From original patch by Andrea: synchronize_rcu/synchronize_sched/synchronize_rcu_expedited() will hang until its own workqueues are run. The i915 gem workqueues will wait on the struct_mutex to be released. So we cannot wait for a quiescent state using those rcu primitives while holding the struct_mutex or it creates a circular lock dependency resulting in kernel hangs (which is reproducible but goes undetected by lockdep). kswapd0 D 0 700 2 0x00000000 Call Trace: ? __schedule+0x1a5/0x660 ? schedule+0x36/0x80 ? _synchronize_rcu_expedited.constprop.65+0x2ef/0x300 ? wake_up_bit+0x20/0x20 ? rcu_stall_kick_kthreads.part.54+0xc0/0xc0 ? rcu_exp_wait_wake+0x530/0x530 ? i915_gem_shrink+0x34b/0x4b0 ? i915_gem_shrinker_scan+0x7c/0x90 ? i915_gem_shrinker_scan+0x7c/0x90 ? shrink_slab.part.61.constprop.72+0x1c1/0x3a0 ? shrink_zone+0x154/0x160 ? kswapd+0x40a/0x720 ? kthread+0xf4/0x130 ? try_to_free_pages+0x450/0x450 ? kthread_create_on_node+0x40/0x40 ? ret_from_fork+0x23/0x30 plasmashell D 0 4657 4614 0x00000000 Call Trace: ? __schedule+0x1a5/0x660 ? schedule+0x36/0x80 ? schedule_preempt_disabled+0xe/0x10 ? __mutex_lock.isra.4+0x1c9/0x790 ? i915_gem_close_object+0x26/0xc0 ? i915_gem_close_object+0x26/0xc0 ? drm_gem_object_release_handle+0x48/0x90 ? drm_gem_handle_delete+0x50/0x80 ? drm_ioctl+0x1fa/0x420 ? drm_gem_handle_create+0x40/0x40 ? pipe_write+0x391/0x410 ? __vfs_write+0xc6/0x120 ? do_vfs_ioctl+0x8b/0x5d0 ? SyS_ioctl+0x3b/0x70 ? entry_SYSCALL_64_fastpath+0x13/0x94 kworker/0:0 D 0 29186 2 0x00000000 Workqueue: events __i915_gem_free_work Call Trace: ? __schedule+0x1a5/0x660 ? schedule+0x36/0x80 ? schedule_preempt_disabled+0xe/0x10 ? __mutex_lock.isra.4+0x1c9/0x790 ? del_timer_sync+0x44/0x50 ? update_curr+0x57/0x110 ? __i915_gem_free_objects+0x31/0x300 ? __i915_gem_free_objects+0x31/0x300 ? __i915_gem_free_work+0x2d/0x40 ? process_one_work+0x13a/0x3b0 ? worker_thread+0x4a/0x460 ? kthread+0xf4/0x130 ? process_one_work+0x3b0/0x3b0 ? kthread_create_on_node+0x40/0x40 ? ret_from_fork+0x23/0x30 Fixes: 3d3d18f086cd ("drm/i915: Avoid rcu_barrier() from reclaim paths (shrinker)") Reported-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Jani Nikula <jani.nikula@intel.com> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (cherry picked from commit 8f612d055183545070ca1009ac2eb1f2e044cc20) Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/gpu/drm/i915/i915_gem_shrinker.c26
1 files changed, 16 insertions, 10 deletions
diff --git a/drivers/gpu/drm/i915/i915_gem_shrinker.c b/drivers/gpu/drm/i915/i915_gem_shrinker.c
index d5d2b4c6ed38..70b3832a79dd 100644
--- a/drivers/gpu/drm/i915/i915_gem_shrinker.c
+++ b/drivers/gpu/drm/i915/i915_gem_shrinker.c
@@ -53,6 +53,17 @@ static bool i915_gem_shrinker_lock(struct drm_device *dev, bool *unlock)
BUG();
}
+static void i915_gem_shrinker_unlock(struct drm_device *dev, bool unlock)
+{
+ if (!unlock)
+ return;
+
+ mutex_unlock(&dev->struct_mutex);
+
+ /* expedite the RCU grace period to free some request slabs */
+ synchronize_rcu_expedited();
+}
+
static bool any_vma_pinned(struct drm_i915_gem_object *obj)
{
struct i915_vma *vma;
@@ -232,11 +243,8 @@ i915_gem_shrink(struct drm_i915_private *dev_priv,
intel_runtime_pm_put(dev_priv);
i915_gem_retire_requests(dev_priv);
- if (unlock)
- mutex_unlock(&dev_priv->drm.struct_mutex);
- /* expedite the RCU grace period to free some request slabs */
- synchronize_rcu_expedited();
+ i915_gem_shrinker_unlock(&dev_priv->drm, unlock);
return count;
}
@@ -293,8 +301,7 @@ i915_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc)
count += obj->base.size >> PAGE_SHIFT;
}
- if (unlock)
- mutex_unlock(&dev->struct_mutex);
+ i915_gem_shrinker_unlock(dev, unlock);
return count;
}
@@ -321,8 +328,8 @@ i915_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc)
sc->nr_to_scan - freed,
I915_SHRINK_BOUND |
I915_SHRINK_UNBOUND);
- if (unlock)
- mutex_unlock(&dev->struct_mutex);
+
+ i915_gem_shrinker_unlock(dev, unlock);
return freed;
}
@@ -364,8 +371,7 @@ i915_gem_shrinker_unlock_uninterruptible(struct drm_i915_private *dev_priv,
struct shrinker_lock_uninterruptible *slu)
{
dev_priv->mm.interruptible = slu->was_interruptible;
- if (slu->unlock)
- mutex_unlock(&dev_priv->drm.struct_mutex);
+ i915_gem_shrinker_unlock(&dev_priv->drm, slu->unlock);
}
static int