1. 12 Oct, 2017 1 commit
    • Chris Wilson's avatar
      drm/i915/userptr: Drop struct_mutex before cleanup · 7c781423
      Chris Wilson authored
      Purely to silence lockdep, as we know that no bo can exist at this time
      and so the inversion is impossible. Nevertheless, lockdep currently
      warns on unload:
      
      [  137.522565] WARNING: possible circular locking dependency detected
      [  137.522568] 4.14.0-rc4-CI-CI_DRM_3209+ #1 Tainted: G     U
      [  137.522570] ------------------------------------------------------
      [  137.522572] drv_module_relo/1532 is trying to acquire lock:
      [  137.522574]  ("i915-userptr-acquire"){+.+.}, at: [<ffffffff8109a831>] flush_workqueue+0x91/0x540
      [  137.522581]
                     but task is already holding lock:
      [  137.522583]  (&dev->struct_mutex){+.+.}, at: [<ffffffffa014fb3f>] i915_gem_fini+0x3f/0xc0 [i915]
      [  137.522605]
                     which lock already depends on the new lock.
      
      [  137.522608]
                     the existing dependency chain (in reverse order) is:
      [  137.522611]
                     -> #3 (&dev->struct_mutex){+.+.}:
      [  137.522615]        __lock_acquire+0x1420/0x15e0
      [  137.522618]        lock_acquire+0xb0/0x200
      [  137.522621]        __mutex_lock+0x86/0x9b0
      [  137.522623]        mutex_lock_interruptible_nested+0x1b/0x20
      [  137.522640]        i915_mutex_lock_interruptible+0x51/0x130 [i915]
      [  137.522657]        i915_gem_fault+0x20b/0x720 [i915]
      [  137.522660]        __do_fault+0x1e/0x80
      [  137.522662]        __handle_mm_fault+0xa08/0xed0
      [  137.522664]        handle_mm_fault+0x156/0x300
      [  137.522666]        __do_page_fault+0x2c5/0x570
      [  137.522668]        do_page_fault+0x28/0x250
      [  137.522671]        page_fault+0x22/0x30
      [  137.522672]
                     -> #2 (&mm->mmap_sem){++++}:
      [  137.522677]        __lock_acquire+0x1420/0x15e0
      [  137.522679]        lock_acquire+0xb0/0x200
      [  137.522682]        down_read+0x3e/0x70
      [  137.522699]        __i915_gem_userptr_get_pages_worker+0x141/0x240 [i915]
      [  137.522701]        process_one_work+0x233/0x660
      [  137.522704]        worker_thread+0x4e/0x3b0
      [  137.522706]        kthread+0x152/0x190
      [  137.522708]        ret_from_fork+0x27/0x40
      [  137.522710]
                     -> #1 ((&work->work)){+.+.}:
      [  137.522714]        __lock_acquire+0x1420/0x15e0
      [  137.522717]        lock_acquire+0xb0/0x200
      [  137.522719]        process_one_work+0x206/0x660
      [  137.522721]        worker_thread+0x4e/0x3b0
      [  137.522723]        kthread+0x152/0x190
      [  137.522725]        ret_from_fork+0x27/0x40
      [  137.522727]
                     -> #0 ("i915-userptr-acquire"){+.+.}:
      [  137.522731]        check_prev_add+0x430/0x840
      [  137.522733]        __lock_acquire+0x1420/0x15e0
      [  137.522735]        lock_acquire+0xb0/0x200
      [  137.522738]        flush_workqueue+0xb4/0x540
      [  137.522740]        drain_workqueue+0xd4/0x1b0
      [  137.522742]        destroy_workqueue+0x1c/0x200
      [  137.522758]        i915_gem_cleanup_userptr+0x15/0x20 [i915]
      [  137.522770]        i915_gem_fini+0x5f/0xc0 [i915]
      [  137.522782]        i915_driver_unload+0x122/0x180 [i915]
      [  137.522794]        i915_pci_remove+0x19/0x30 [i915]
      [  137.522797]        pci_device_remove+0x39/0xb0
      [  137.522800]        device_release_driver_internal+0x15d/0x220
      [  137.522803]        driver_detach+0x40/0x80
      [  137.522805]        bus_remove_driver+0x58/0xd0
      [  137.522807]        driver_unregister+0x2c/0x40
      [  137.522809]        pci_unregister_driver+0x36/0xb0
      [  137.522828]        i915_exit+0x1a/0x8b [i915]
      [  137.522831]        SyS_delete_module+0x18c/0x1e0
      [  137.522834]        entry_SYSCALL_64_fastpath+0x1c/0xb1
      [  137.522835]
                     other info that might help us debug this:
      
      [  137.522838] Chain exists of:
                       "i915-userptr-acquire" --> &mm->mmap_sem --> &dev->struct_mutex
      
      [  137.522844]  Possible unsafe locking scenario:
      
      [  137.522846]        CPU0                    CPU1
      [  137.522848]        ----                    ----
      [  137.522850]   lock(&dev->struct_mutex);
      [  137.522852]                                lock(&mm->mmap_sem);
      [  137.522854]                                lock(&dev->struct_mutex);
      [  137.522857]   lock("i915-userptr-acquire");
      [  137.522859]
                      *** DEADLOCK ***
      
      [  137.522862] 3 locks held by drv_module_relo/1532:
      [  137.522864]  #0:  (&dev->mutex){....}, at: [<ffffffff8161d47b>] device_release_driver_internal+0x2b/0x220
      [  137.522869]  #1:  (&dev->mutex){....}, at: [<ffffffff8161d489>] device_release_driver_internal+0x39/0x220
      [  137.522873]  #2:  (&dev->struct_mutex){+.+.}, at: [<ffffffffa014fb3f>] i915_gem_fini+0x3f/0xc0 [i915]
      [  137.522888]
                     stack backtrace:
      [  137.522891] CPU: 0 PID: 1532 Comm: drv_module_relo Tainted: G     U          4.14.0-rc4-CI-CI_DRM_3209+ #1
      [  137.522894] Hardware name:                  /NUC7i5BNB, BIOS BNKBL357.86A.0048.2017.0704.1415 07/04/2017
      [  137.522897] Call Trace:
      [  137.522900]  dump_stack+0x68/0x9f
      [  137.522902]  print_circular_bug+0x235/0x3c0
      [  137.522905]  ? lockdep_init_map_crosslock+0x20/0x20
      [  137.522908]  check_prev_add+0x430/0x840
      [  137.522919]  ? i915_gem_fini+0x5f/0xc0 [i915]
      [  137.522922]  ? __kernel_text_address+0x12/0x40
      [  137.522925]  ? __save_stack_trace+0x66/0xd0
      [  137.522928]  __lock_acquire+0x1420/0x15e0
      [  137.522930]  ? __lock_acquire+0x1420/0x15e0
      [  137.522933]  ? lockdep_init_map_crosslock+0x20/0x20
      [  137.522936]  ? __this_cpu_preempt_check+0x13/0x20
      [  137.522938]  lock_acquire+0xb0/0x200
      [  137.522940]  ? flush_workqueue+0x91/0x540
      [  137.522943]  flush_workqueue+0xb4/0x540
      [  137.522945]  ? flush_workqueue+0x91/0x540
      [  137.522948]  ? __mutex_unlock_slowpath+0x43/0x2c0
      [  137.522951]  ? trace_hardirqs_on_caller+0xe3/0x1b0
      [  137.522954]  drain_workqueue+0xd4/0x1b0
      [  137.522956]  ? drain_workqueue+0xd4/0x1b0
      [  137.522958]  destroy_workqueue+0x1c/0x200
      [  137.522975]  i915_gem_cleanup_userptr+0x15/0x20 [i915]
      [  137.522987]  i915_gem_fini+0x5f/0xc0 [i915]
      [  137.523000]  i915_driver_unload+0x122/0x180 [i915]
      [  137.523015]  i915_pci_remove+0x19/0x30 [i915]
      [  137.523018]  pci_device_remove+0x39/0xb0
      [  137.523021]  device_release_driver_internal+0x15d/0x220
      [  137.523023]  driver_detach+0x40/0x80
      [  137.523026]  bus_remove_driver+0x58/0xd0
      [  137.523028]  driver_unregister+0x2c/0x40
      [  137.523030]  pci_unregister_driver+0x36/0xb0
      [  137.523049]  i915_exit+0x1a/0x8b [i915]
      [  137.523052]  SyS_delete_module+0x18c/0x1e0
      [  137.523055]  entry_SYSCALL_64_fastpath+0x1c/0xb1
      [  137.523057] RIP: 0033:0x7f7bd0609287
      [  137.523059] RSP: 002b:00007ffef694bc18 EFLAGS: 00000246 ORIG_RAX: 00000000000000b0
      [  137.523062] RAX: ffffffffffffffda RBX: ffffffff81493f33 RCX: 00007f7bd0609287
      [  137.523065] RDX: 0000000000000001 RSI: 0000000000000800 RDI: 0000564f999f9fc8
      [  137.523067] RBP: ffffc90005c4ff88 R08: 0000000000000000 R09: 0000000000000080
      [  137.523069] R10: 00007f7bd20ef8c0 R11: 0000000000000246 R12: 0000000000000000
      [  137.523072] R13: 00007ffef694be00 R14: 0000000000000000 R15: 0000000000000000
      [  137.523075]  ? __this_cpu_preempt_check+0x13/0x20
      Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
      Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Link: https://patchwork.freedesktop.org/patch/msgid/20171011141857.14161-1-chris@chris-wilson.co.ukReviewed-by: default avatarDaniel Vetter <daniel.vetter@ffwll.ch>
      7c781423
  2. 11 Oct, 2017 17 commits
  3. 10 Oct, 2017 22 commits