• M
    drm/i915/guc: Move GuC workqueue allocations outside of the mutex · 3176ff49
    Michał Winiarski 提交于
    This gets rid of the following lockdep splat:
    
    ======================================================
    WARNING: possible circular locking dependency detected
    4.15.0-rc2-CI-Patchwork_7428+ #1 Not tainted
    ------------------------------------------------------
    debugfs_test/1351 is trying to acquire lock:
     (&dev->struct_mutex){+.+.}, at: [<000000009d90d1a3>] i915_mutex_lock_interruptible+0x47/0x130 [i915]
    
    but task is already holding lock:
     (&mm->mmap_sem){++++}, at: [<000000005df01c1e>] __do_page_fault+0x106/0x560
    
    which lock already depends on the new lock.
    
    the existing dependency chain (in reverse order) is:
    
    -> #6 (&mm->mmap_sem){++++}:
           __might_fault+0x63/0x90
           _copy_to_user+0x1e/0x70
           filldir+0x8c/0xf0
           dcache_readdir+0xeb/0x160
           iterate_dir+0xe6/0x150
           SyS_getdents+0xa0/0x130
           entry_SYSCALL_64_fastpath+0x1c/0x89
    
    -> #5 (&sb->s_type->i_mutex_key#5){++++}:
           lockref_get+0x9/0x20
    
    -> #4 ((completion)&req.done){+.+.}:
           wait_for_common+0x54/0x210
           devtmpfs_create_node+0x130/0x150
           device_add+0x5ad/0x5e0
           device_create_groups_vargs+0xd4/0xe0
           device_create+0x35/0x40
           msr_device_create+0x22/0x40
           cpuhp_invoke_callback+0xc5/0xbf0
           cpuhp_thread_fun+0x167/0x210
           smpboot_thread_fn+0x17f/0x270
           kthread+0x173/0x1b0
           ret_from_fork+0x24/0x30
    
    -> #3 (cpuhp_state-up){+.+.}:
           cpuhp_issue_call+0x132/0x1c0
           __cpuhp_setup_state_cpuslocked+0x12f/0x2a0
           __cpuhp_setup_state+0x3a/0x50
           page_writeback_init+0x3a/0x5c
           start_kernel+0x393/0x3e2
           secondary_startup_64+0xa5/0xb0
    
    -> #2 (cpuhp_state_mutex){+.+.}:
           __mutex_lock+0x81/0x9b0
           __cpuhp_setup_state_cpuslocked+0x4b/0x2a0
           __cpuhp_setup_state+0x3a/0x50
           page_alloc_init+0x1f/0x26
           start_kernel+0x139/0x3e2
           secondary_startup_64+0xa5/0xb0
    
    -> #1 (cpu_hotplug_lock.rw_sem){++++}:
           cpus_read_lock+0x34/0xa0
           apply_workqueue_attrs+0xd/0x40
           __alloc_workqueue_key+0x2c7/0x4e1
           intel_guc_submission_init+0x10c/0x650 [i915]
           intel_uc_init_hw+0x29e/0x460 [i915]
           i915_gem_init_hw+0xca/0x290 [i915]
           i915_gem_init+0x115/0x3a0 [i915]
           i915_driver_load+0x9a8/0x16c0 [i915]
           i915_pci_probe+0x2e/0x90 [i915]
           pci_device_probe+0x9c/0x120
           driver_probe_device+0x2a3/0x480
           __driver_attach+0xd9/0xe0
           bus_for_each_dev+0x57/0x90
           bus_add_driver+0x168/0x260
           driver_register+0x52/0xc0
           do_one_initcall+0x39/0x150
           do_init_module+0x56/0x1ef
           load_module+0x231c/0x2d70
           SyS_finit_module+0xa5/0xe0
           entry_SYSCALL_64_fastpath+0x1c/0x89
    
    -> #0 (&dev->struct_mutex){+.+.}:
           lock_acquire+0xaf/0x200
           __mutex_lock+0x81/0x9b0
           i915_mutex_lock_interruptible+0x47/0x130 [i915]
           i915_gem_fault+0x201/0x760 [i915]
           __do_fault+0x15/0x70
           __handle_mm_fault+0x85b/0xe40
           handle_mm_fault+0x14f/0x2f0
           __do_page_fault+0x2d1/0x560
           page_fault+0x22/0x30
    
    other info that might help us debug this:
    
    Chain exists of:
      &dev->struct_mutex --> &sb->s_type->i_mutex_key#5 --> &mm->mmap_sem
    
     Possible unsafe locking scenario:
    
           CPU0                    CPU1
           ----                    ----
      lock(&mm->mmap_sem);
                                   lock(&sb->s_type->i_mutex_key#5);
                                   lock(&mm->mmap_sem);
      lock(&dev->struct_mutex);
    
     *** DEADLOCK ***
    
    1 lock held by debugfs_test/1351:
     #0:  (&mm->mmap_sem){++++}, at: [<000000005df01c1e>] __do_page_fault+0x106/0x560
    
    stack backtrace:
    CPU: 2 PID: 1351 Comm: debugfs_test Not tainted 4.15.0-rc2-CI-Patchwork_7428+ #1
    Hardware name:                  /NUC6i5SYB, BIOS SYSKLi35.86A.0057.2017.0119.1758 01/19/2017
    Call Trace:
     dump_stack+0x5f/0x86
     print_circular_bug+0x230/0x3b0
     check_prev_add+0x439/0x7b0
     ? lockdep_init_map_crosslock+0x20/0x20
     ? unwind_get_return_address+0x16/0x30
     ? __lock_acquire+0x1385/0x15a0
     __lock_acquire+0x1385/0x15a0
     lock_acquire+0xaf/0x200
     ? i915_mutex_lock_interruptible+0x47/0x130 [i915]
     __mutex_lock+0x81/0x9b0
     ? i915_mutex_lock_interruptible+0x47/0x130 [i915]
     ? i915_mutex_lock_interruptible+0x47/0x130 [i915]
     ? i915_mutex_lock_interruptible+0x47/0x130 [i915]
     i915_mutex_lock_interruptible+0x47/0x130 [i915]
     ? __pm_runtime_resume+0x4f/0x80
     i915_gem_fault+0x201/0x760 [i915]
     __do_fault+0x15/0x70
     __handle_mm_fault+0x85b/0xe40
     handle_mm_fault+0x14f/0x2f0
     __do_page_fault+0x2d1/0x560
     page_fault+0x22/0x30
    RIP: 0033:0x7f98d6f49116
    RSP: 002b:00007ffd6ffc3278 EFLAGS: 00010283
    RAX: 00007f98d39a2bc0 RBX: 0000000000000000 RCX: 0000000000001680
    RDX: 0000000000001680 RSI: 00007ffd6ffc3400 RDI: 00007f98d39a2bc0
    RBP: 00007ffd6ffc33a0 R08: 0000000000000000 R09: 00000000000005a0
    R10: 000055e847c2a830 R11: 0000000000000002 R12: 0000000000000001
    R13: 000055e847c1d040 R14: 00007ffd6ffc3400 R15: 00007f98d6752ba0
    
    v2: Init preempt_work unconditionally (Chris)
    v3: Mention that we need the enable_guc=1 for lockdep splat (Chris)
    
    Testcase: igt/debugfs_test/read_all_entries # with i915.enable_guc=1
    Signed-off-by: NMichał Winiarski <michal.winiarski@intel.com>
    Cc: Chris Wilson <chris@chris-wilson.co.uk>
    Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
    Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
    Reviewed-by: NChris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
    Link: https://patchwork.freedesktop.org/patch/msgid/20171213221352.7173-2-michal.winiarski@intel.com
    3176ff49
intel_guc_submission.h 3.3 KB