From 4676dc838b37ed8c6f3da4571cb4a04cbd604801 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 12 Oct 2016 12:48:26 +0100 Subject: [PATCH] drm/i915: Use fence_write() from rpm resume MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit During rpm resume we restore the fences, but we do not have the protection of struct_mutex. This rules out updating the activity tracking on the fences, and requires us to rely on the rpm as the serialisation barrier instead. [ 350.298052] [drm:intel_runtime_resume [i915]] Resuming device [ 350.308606] [ 350.310520] =============================== [ 350.315560] [ INFO: suspicious RCU usage. ] [ 350.320554] 4.8.0-rc8-bsw-rapl+ #3133 Tainted: G U W [ 350.327208] ------------------------------- [ 350.331977] ../drivers/gpu/drm/i915/i915_gem_request.h:371 suspicious rcu_dereference_protected() usage! [ 350.342619] [ 350.342619] other info that might help us debug this: [ 350.342619] [ 350.351593] [ 350.351593] rcu_scheduler_active = 1, debug_locks = 0 [ 350.358952] 3 locks held by Xorg/320: [ 350.363077] #0: (&dev->mode_config.mutex){+.+.+.}, at: [] drm_modeset_lock_all+0x3c/0xd0 [drm] [ 350.375162] #1: (crtc_ww_class_acquire){+.+.+.}, at: [] drm_modeset_lock_all+0x46/0xd0 [drm] [ 350.387022] #2: (crtc_ww_class_mutex){+.+.+.}, at: [] drm_modeset_lock+0x36/0x110 [drm] [ 350.398236] [ 350.398236] stack backtrace: [ 350.403196] CPU: 1 PID: 320 Comm: Xorg Tainted: G U W 4.8.0-rc8-bsw-rapl+ #3133 [ 350.412457] Hardware name: Intel Corporation CHERRYVIEW C0 PLATFORM/Braswell CRB, BIOS BRAS.X64.X088.R00.1510270350 10/27/2015 [ 350.425212] 0000000000000000 ffff8801680a78c8 ffffffff81332187 ffff88016c5c5000 [ 350.433611] 0000000000000001 ffff8801680a78f8 ffffffff810ca6da ffff88016cc8b0f0 [ 350.442012] ffff88016cc80000 ffff88016cc80000 ffff880177ad0000 ffff8801680a7948 [ 350.450409] Call Trace: [ 350.453165] [] dump_stack+0x67/0x90 [ 350.458931] [] lockdep_rcu_suspicious+0xea/0x120 [ 350.466002] [] fence_update+0xbd/0x670 [i915] [ 350.472766] [] i915_gem_restore_fences+0x52/0x70 [i915] [ 350.480496] [] vlv_resume_prepare+0x72/0x570 [i915] [ 350.487839] [] intel_runtime_resume+0x102/0x210 [i915] [ 350.495442] [] pci_pm_runtime_resume+0x7f/0xb0 [ 350.502274] [] ? pci_restore_standard_config+0x40/0x40 [ 350.509883] [] __rpm_callback+0x35/0x70 [ 350.516037] [] ? pci_restore_standard_config+0x40/0x40 [ 350.523646] [] rpm_callback+0x24/0x80 [ 350.529604] [] ? pci_restore_standard_config+0x40/0x40 [ 350.537212] [] rpm_resume+0x4ad/0x740 [ 350.543161] [] __pm_runtime_resume+0x51/0x80 [ 350.549824] [] intel_runtime_pm_get+0x28/0x90 [i915] [ 350.557265] [] intel_display_power_get+0x23/0x50 [i915] [ 350.565001] [] intel_atomic_commit_tail+0xdfd/0x10b0 [i915] [ 350.573106] [] ? drm_atomic_helper_swap_state+0x159/0x300 [drm_kms_helper] [ 350.582659] [] ? _raw_spin_unlock+0x31/0x50 [ 350.589205] [] ? drm_atomic_helper_swap_state+0x159/0x300 [drm_kms_helper] [ 350.598787] [] intel_atomic_commit+0x3b5/0x500 [i915] [ 350.606319] [] ? drm_atomic_set_crtc_for_connector+0xcc/0x100 [drm] [ 350.615209] [] drm_atomic_commit+0x49/0x50 [drm] [ 350.622242] [] drm_atomic_helper_set_config+0x88/0xc0 [drm_kms_helper] [ 350.631419] [] drm_mode_set_config_internal+0x6c/0x120 [drm] [ 350.639623] [] drm_mode_setcrtc+0x22c/0x4d0 [drm] [ 350.646760] [] drm_ioctl+0x209/0x460 [drm] [ 350.653217] [] ? drm_mode_getcrtc+0x150/0x150 [drm] [ 350.660536] [] ? __lock_is_held+0x4a/0x70 [ 350.666885] [] do_vfs_ioctl+0x93/0x6b0 [ 350.672939] [] ? __fget+0x113/0x200 [ 350.678797] [] ? __fget+0x5/0x200 [ 350.684361] [] SyS_ioctl+0x44/0x80 [ 350.690030] [] do_syscall_64+0x5b/0x120 [ 350.696184] [] entry_SYSCALL64_slow_path+0x25/0x25 Note we also have to remember the lesson from commit 4fc788f5ee3d ("drm/i915: Flush delayed fence releases after reset") where we have to flush any changes to the fence on restore. v2: Replace call to release user mmaps with an assertion that they have already been zapped. Fixes: 49ef5294cda2 ("drm/i915: Move fence tracking from object to vma") Reported-by: Ville Syrjälä Signed-off-by: Chris Wilson Cc: Ville Syrjälä Cc: Joonas Lahtinen Cc: Mika Kuoppala Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20161012114827.17031-1-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem_fence.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_fence.c b/drivers/gpu/drm/i915/i915_gem_fence.c index 8df1fa7234e8..2c7ba0ee127c 100644 --- a/drivers/gpu/drm/i915/i915_gem_fence.c +++ b/drivers/gpu/drm/i915/i915_gem_fence.c @@ -290,6 +290,8 @@ i915_vma_put_fence(struct i915_vma *vma) { struct drm_i915_fence_reg *fence = vma->fence; + assert_rpm_wakelock_held(to_i915(vma->vm->dev)); + if (!fence) return 0; @@ -341,6 +343,8 @@ i915_vma_get_fence(struct i915_vma *vma) struct drm_i915_fence_reg *fence; struct i915_vma *set = i915_gem_object_is_tiled(vma->obj) ? vma : NULL; + assert_rpm_wakelock_held(to_i915(vma->vm->dev)); + /* Just update our place in the LRU if our fence is getting reused. */ if (vma->fence) { fence = vma->fence; @@ -371,6 +375,12 @@ void i915_gem_restore_fences(struct drm_device *dev) struct drm_i915_private *dev_priv = to_i915(dev); int i; + /* Note that this may be called outside of struct_mutex, by + * runtime suspend/resume. The barrier we require is enforced by + * rpm itself - all access to fences/GTT are only within an rpm + * wakeref, and to acquire that wakeref you must pass through here. + */ + for (i = 0; i < dev_priv->num_fence_regs; i++) { struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i]; struct i915_vma *vma = reg->vma; @@ -379,10 +389,17 @@ void i915_gem_restore_fences(struct drm_device *dev) * Commit delayed tiling changes if we have an object still * attached to the fence, otherwise just clear the fence. */ - if (vma && !i915_gem_object_is_tiled(vma->obj)) + if (vma && !i915_gem_object_is_tiled(vma->obj)) { + GEM_BUG_ON(!reg->dirty); + GEM_BUG_ON(vma->obj->fault_mappable); + + list_move(®->link, &dev_priv->mm.fence_list); + vma->fence = NULL; vma = NULL; + } - fence_update(reg, vma); + fence_write(reg, vma); + reg->vma = vma; } } -- 2.39.5