* [PATCH] drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
@ 2017-04-07 9:00 Joonas Lahtinen
2017-04-07 9:18 ` ✓ Fi.CI.BAT: success for " Patchwork
0 siblings, 1 reply; 3+ messages in thread
From: Joonas Lahtinen @ 2017-04-07 9:00 UTC (permalink / raw)
To: Intel graphics driver community testing & development
Cc: Andrea Arcangeli, Daniel Vetter, Jani Nikula
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>
---
drivers/gpu/drm/i915/i915_gem_shrinker.c | 26 ++++++++++++++++----------
1 file 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 2978acd..129ed30 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;
}
@@ -296,8 +304,7 @@ 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;
}
@@ -324,8 +331,8 @@ 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;
}
@@ -367,8 +374,7 @@ 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
--
2.7.4
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
^ permalink raw reply related [flat|nested] 3+ messages in thread
* ✓ Fi.CI.BAT: success for drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
2017-04-07 9:00 [PATCH] drm/i915: Don't call synchronize_rcu_expedited under struct_mutex Joonas Lahtinen
@ 2017-04-07 9:18 ` Patchwork
2017-04-07 9:34 ` Chris Wilson
0 siblings, 1 reply; 3+ messages in thread
From: Patchwork @ 2017-04-07 9:18 UTC (permalink / raw)
To: Joonas Lahtinen; +Cc: intel-gfx
== Series Details ==
Series: drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
URL : https://patchwork.freedesktop.org/series/22646/
State : success
== Summary ==
Series 22646v1 drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
https://patchwork.freedesktop.org/api/1.0/series/22646/revisions/1/mbox/
Test gem_exec_flush:
Subgroup basic-batch-kernel-default-uc:
pass -> FAIL (fi-snb-2600) fdo#100007
fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007
fi-bdw-5557u total:278 pass:267 dwarn:0 dfail:0 fail:0 skip:11 time: 434s
fi-bdw-gvtdvm total:278 pass:256 dwarn:8 dfail:0 fail:0 skip:14 time: 424s
fi-bsw-n3050 total:278 pass:242 dwarn:0 dfail:0 fail:0 skip:36 time: 575s
fi-bxt-j4205 total:278 pass:259 dwarn:0 dfail:0 fail:0 skip:19 time: 507s
fi-bxt-t5700 total:278 pass:257 dwarn:1 dfail:0 fail:0 skip:20 time: 556s
fi-byt-j1900 total:278 pass:254 dwarn:0 dfail:0 fail:0 skip:24 time: 485s
fi-byt-n2820 total:278 pass:250 dwarn:0 dfail:0 fail:0 skip:28 time: 476s
fi-hsw-4770 total:278 pass:262 dwarn:0 dfail:0 fail:0 skip:16 time: 411s
fi-hsw-4770r total:278 pass:262 dwarn:0 dfail:0 fail:0 skip:16 time: 406s
fi-ilk-650 total:278 pass:228 dwarn:0 dfail:0 fail:0 skip:50 time: 420s
fi-ivb-3520m total:278 pass:260 dwarn:0 dfail:0 fail:0 skip:18 time: 493s
fi-ivb-3770 total:278 pass:260 dwarn:0 dfail:0 fail:0 skip:18 time: 464s
fi-kbl-7500u total:278 pass:260 dwarn:0 dfail:0 fail:0 skip:18 time: 458s
fi-kbl-7560u total:278 pass:268 dwarn:0 dfail:0 fail:0 skip:10 time: 660s
fi-skl-6260u total:278 pass:268 dwarn:0 dfail:0 fail:0 skip:10 time: 455s
fi-skl-6700hq total:278 pass:261 dwarn:0 dfail:0 fail:0 skip:17 time: 570s
fi-skl-6700k total:278 pass:256 dwarn:4 dfail:0 fail:0 skip:18 time: 454s
fi-skl-6770hq total:278 pass:268 dwarn:0 dfail:0 fail:0 skip:10 time: 486s
fi-skl-gvtdvm total:278 pass:265 dwarn:0 dfail:0 fail:0 skip:13 time: 429s
fi-snb-2520m total:278 pass:250 dwarn:0 dfail:0 fail:0 skip:28 time: 530s
fi-snb-2600 total:278 pass:248 dwarn:0 dfail:0 fail:1 skip:29 time: 396s
60e3f75dfa48d8943d4d4d57bbd7ef7c1d037d85 drm-tip: 2017y-04m-07d-07h-32m-05s UTC integration manifest
536e14a drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
== Logs ==
For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4437/
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: ✓ Fi.CI.BAT: success for drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
2017-04-07 9:18 ` ✓ Fi.CI.BAT: success for " Patchwork
@ 2017-04-07 9:34 ` Chris Wilson
0 siblings, 0 replies; 3+ messages in thread
From: Chris Wilson @ 2017-04-07 9:34 UTC (permalink / raw)
To: intel-gfx
On Fri, Apr 07, 2017 at 09:18:17AM -0000, Patchwork wrote:
> == Series Details ==
>
> Series: drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
> URL : https://patchwork.freedesktop.org/series/22646/
> State : success
>
> == Summary ==
>
> Series 22646v1 drm/i915: Don't call synchronize_rcu_expedited under struct_mutex
> https://patchwork.freedesktop.org/api/1.0/series/22646/revisions/1/mbox/
Slow mbox. So reply here instead.
Hmm, so that fixes the immediate problem with struct_mutex, but there is
still a danger that we are underneath some other mutex that is being
waited upon. I think it is too dangerous to live and that kswapd should
have the role of expediting the RCU cleanup.
Since the patch improves the situation,
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
But please do follow up with a
- synchronize_rcu_expedited();
+ /* We rely on the system flushing the RCU slabs to free our structs */
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2017-04-07 9:35 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-04-07 9:00 [PATCH] drm/i915: Don't call synchronize_rcu_expedited under struct_mutex Joonas Lahtinen
2017-04-07 9:18 ` ✓ Fi.CI.BAT: success for " Patchwork
2017-04-07 9:34 ` Chris Wilson
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.