![]() 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: |
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drm | ||
host1x | ||
ipu-v3 | ||
vga | ||
Makefile |