deadlock possiblity introduced by "drm/nouveau: use drm_mm in preference to custom code doing the same thing"
Ben Skeggs
skeggsb at gmail.com
Sat Jul 10 18:02:12 PDT 2010
On Sun, 2010-07-11 at 01:24 +0200, Marcin Slusarz wrote:
> Hi
>
> Patch "drm/nouveau: use drm_mm in preference to custom code doing the same thing"
> in nouveau tree introduced new deadlock possibility, for which lockdep complains loudly:
>
> [ 1541.070202] [drm] nouveau 0000:02:00.0: Allocating FIFO number 3
> [ 1541.084772] [drm] nouveau 0000:02:00.0: nouveau_channel_alloc: initialised FIFO 3
> [ 2417.733440] [drm] nouveau 0000:02:00.0: nouveau_channel_free: freeing fifo 3
> [ 2417.746638]
> [ 2417.746639] ======================================================
> [ 2417.746642] [ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
> [ 2417.746644] 2.6.35-rc4-nv+ #379
> [ 2417.746645] ------------------------------------------------------
> [ 2417.746648] warsow/2850 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
> [ 2417.746650] (&(&mm->unused_lock)->rlock){+.+...}, at: [<ffffffff8129f0c0>] drm_mm_put_block+0x17a/0x1c0
> [ 2417.746657]
> [ 2417.746658] and this task is already holding:
> [ 2417.746659] (&(&dev_priv->context_switch_lock)->rlock){-.....}, at: [<ffffffffa00ac502>] nouveau_channel_free+0x10f/0x233 [nouveau]
> [ 2417.746669] which would create a new lock dependency:
> [ 2417.746671] (&(&dev_priv->context_switch_lock)->rlock){-.....} -> (&(&mm->unused_lock)->rlock){+.+...}
> [ 2417.746676]
> [ 2417.746676] but this new dependency connects a HARDIRQ-irq-safe lock:
> [ 2417.746678] (&(&dev_priv->context_switch_lock)->rlock){-.....}
> [ 2417.746680] ... which became HARDIRQ-irq-safe at:
> [ 2417.746682] [<ffffffff8109739e>] __lock_acquire+0x671/0x8f4
> [ 2417.746685] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.746688] [<ffffffff8143b2cd>] _raw_spin_lock_irqsave+0x41/0x53
> [ 2417.746692] [<ffffffffa00b3072>] nouveau_irq_handler+0x56/0xa48 [nouveau]
> [ 2417.746698] [<ffffffff810a7b3b>] handle_IRQ_event+0xec/0x25d
> [ 2417.746702] [<ffffffff810a98e1>] handle_fasteoi_irq+0x92/0xd2
> [ 2417.746705] [<ffffffff81032953>] handle_irq+0x83/0x8c
> [ 2417.746707] [<ffffffff81031f19>] do_IRQ+0x57/0xbe
> [ 2417.746711] [<ffffffff8143bf13>] ret_from_intr+0x0/0xf
> [ 2417.746714] [<ffffffff8102f085>] cpu_idle+0x5c/0xb3
> [ 2417.746717] [<ffffffff81434180>] start_secondary+0x1c7/0x1cb
> [ 2417.746720]
> [ 2417.746720] to a HARDIRQ-irq-unsafe lock:
> [ 2417.746722] (&(&mm->unused_lock)->rlock){+.+...}
> [ 2417.746724] ... which became HARDIRQ-irq-unsafe at:
> [ 2417.746725] ... [<ffffffff81097418>] __lock_acquire+0x6eb/0x8f4
> [ 2417.746729] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.746732] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.746735] [<ffffffff8129f641>] drm_mm_pre_get+0x20/0x1a7
> [ 2417.746738] [<ffffffffa00963f2>] ttm_bo_init+0x234/0x385 [ttm]
> [ 2417.746743] [<ffffffffa00b67e4>] nouveau_bo_new+0x366/0x3eb [nouveau]
> [ 2417.746750] [<ffffffffa00ad341>] nouveau_mem_init+0x262/0x44a [nouveau]
> [ 2417.746756] [<ffffffffa00ab8b6>] nouveau_card_init+0xa73/0xd7e [nouveau]
> [ 2417.746761] [<ffffffffa00ac27b>] nouveau_load+0x6ba/0x70a [nouveau]
> [ 2417.746766] [<ffffffff8129b613>] drm_get_dev+0x470/0x5a1
> [ 2417.746769] [<ffffffffa0108b24>] nouveau_pci_probe+0x10/0x12 [nouveau]
> [ 2417.746778] [<ffffffff8121f2c7>] local_pci_probe+0x12/0x16
> [ 2417.746781] [<ffffffff8121faaf>] pci_device_probe+0x60/0x8f
> [ 2417.746784] [<ffffffff812aced7>] driver_probe_device+0xa7/0x136
> [ 2417.746788] [<ffffffff812acfc2>] __driver_attach+0x5c/0x80
> [ 2417.746790] [<ffffffff812ac632>] bus_for_each_dev+0x54/0x89
> [ 2417.746793] [<ffffffff812acd46>] driver_attach+0x19/0x1b
> [ 2417.746796] [<ffffffff812abf48>] bus_add_driver+0x183/0x2ef
> [ 2417.746799] [<ffffffff812ad28f>] driver_register+0x98/0x109
> [ 2417.746801] [<ffffffff8121fd1f>] __pci_register_driver+0x63/0xd3
> [ 2417.746805] [<ffffffff81295f78>] drm_init+0x6b/0xd1
> [ 2417.746807] [<ffffffffa0128048>] 0xffffffffa0128048
> [ 2417.746810] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
> [ 2417.746814] [<ffffffff810a2b0f>] sys_init_module+0x9c/0x1dd
> [ 2417.746817] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.746820]
> [ 2417.746820] other info that might help us debug this:
> [ 2417.746821]
> [ 2417.746823] 1 lock held by warsow/2850:
> [ 2417.746824] #0: (&(&dev_priv->context_switch_lock)->rlock){-.....}, at: [<ffffffffa00ac502>] nouveau_channel_free+0x10f/0x233 [nouveau]
> [ 2417.746833]
> [ 2417.746833] the dependencies between HARDIRQ-irq-safe lock and the holding lock:
> [ 2417.746841] -> (&(&dev_priv->context_switch_lock)->rlock){-.....} ops: 18 {
> [ 2417.746845] IN-HARDIRQ-W at:
> [ 2417.746847] [<ffffffff8109739e>] __lock_acquire+0x671/0x8f4
> [ 2417.746851] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.746854] [<ffffffff8143b2cd>] _raw_spin_lock_irqsave+0x41/0x53
> [ 2417.746858] [<ffffffffa00b3072>] nouveau_irq_handler+0x56/0xa48 [nouveau]
> [ 2417.746865] [<ffffffff810a7b3b>] handle_IRQ_event+0xec/0x25d
> [ 2417.746868] [<ffffffff810a98e1>] handle_fasteoi_irq+0x92/0xd2
> [ 2417.746871] [<ffffffff81032953>] handle_irq+0x83/0x8c
> [ 2417.746874] [<ffffffff81031f19>] do_IRQ+0x57/0xbe
> [ 2417.746878] [<ffffffff8143bf13>] ret_from_intr+0x0/0xf
> [ 2417.746881] [<ffffffff8102f085>] cpu_idle+0x5c/0xb3
> [ 2417.746885] [<ffffffff81434180>] start_secondary+0x1c7/0x1cb
> [ 2417.746888] INITIAL USE at:
> [ 2417.746890] [<ffffffff81097494>] __lock_acquire+0x767/0x8f4
> [ 2417.746893] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.746897] [<ffffffff8143b2cd>] _raw_spin_lock_irqsave+0x41/0x53
> [ 2417.746900] [<ffffffffa00d3fd7>] nv50_fifo_create_context+0x17d/0x485 [nouveau]
> [ 2417.746910] [<ffffffffa00accea>] nouveau_channel_alloc+0x5c7/0x693 [nouveau]
> [ 2417.746915] [<ffffffffa00ab9b5>] nouveau_card_init+0xb72/0xd7e [nouveau]
> [ 2417.746921] [<ffffffffa00ac27b>] nouveau_load+0x6ba/0x70a [nouveau]
> [ 2417.746927] [<ffffffff8129b613>] drm_get_dev+0x470/0x5a1
> [ 2417.746930] [<ffffffffa0108b24>] nouveau_pci_probe+0x10/0x12 [nouveau]
> [ 2417.746939] [<ffffffff8121f2c7>] local_pci_probe+0x12/0x16
> [ 2417.746942] [<ffffffff8121faaf>] pci_device_probe+0x60/0x8f
> [ 2417.746946] [<ffffffff812aced7>] driver_probe_device+0xa7/0x136
> [ 2417.746949] [<ffffffff812acfc2>] __driver_attach+0x5c/0x80
> [ 2417.746952] [<ffffffff812ac632>] bus_for_each_dev+0x54/0x89
> [ 2417.746955] [<ffffffff812acd46>] driver_attach+0x19/0x1b
> [ 2417.746958] [<ffffffff812abf48>] bus_add_driver+0x183/0x2ef
> [ 2417.746962] [<ffffffff812ad28f>] driver_register+0x98/0x109
> [ 2417.746965] [<ffffffff8121fd1f>] __pci_register_driver+0x63/0xd3
> [ 2417.746969] [<ffffffff81295f78>] drm_init+0x6b/0xd1
> [ 2417.746972] [<ffffffffa0128048>] 0xffffffffa0128048
> [ 2417.746975] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
> [ 2417.746978] [<ffffffff810a2b0f>] sys_init_module+0x9c/0x1dd
> [ 2417.746981] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.746985] }
> [ 2417.746986] ... key at: [<ffffffffa011a990>] __key.39000+0x0/0xfffffffffffee196 [nouveau]
> [ 2417.746992] ... acquired at:
> [ 2417.746994] [<ffffffff81095dea>] check_irq_usage+0x5d/0xbe
> [ 2417.746997] [<ffffffff81096754>] validate_chain+0x74a/0xd23
> [ 2417.746999] [<ffffffff810975b0>] __lock_acquire+0x883/0x8f4
> [ 2417.747002] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747005] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747008] [<ffffffff8129f0c0>] drm_mm_put_block+0x17a/0x1c0
> [ 2417.747011] [<ffffffffa00aed3e>] nouveau_gpuobj_del+0x167/0x1b5 [nouveau]
> [ 2417.747017] [<ffffffffa00af553>] nouveau_gpuobj_ref_del+0x2f3/0x31a [nouveau]
> [ 2417.747023] [<ffffffffa00dc365>] nv50_graph_destroy_context+0xf1/0xfd [nouveau]
> [ 2417.747032] [<ffffffffa00ac534>] nouveau_channel_free+0x141/0x233 [nouveau]
> [ 2417.747037] [<ffffffffa00ac695>] nouveau_ioctl_fifo_free+0x6f/0x73 [nouveau]
> [ 2417.747043] [<ffffffff81295cc2>] drm_ioctl+0x27b/0x347
> [ 2417.747045] [<ffffffff8110c51d>] vfs_ioctl+0x2d/0xa1
> [ 2417.747049] [<ffffffff8110ca69>] do_vfs_ioctl+0x454/0x48d
> [ 2417.747052] [<ffffffff8110cae4>] sys_ioctl+0x42/0x65
> [ 2417.747055] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.747058]
> [ 2417.747059]
> [ 2417.747060] the dependencies between the lock to be acquired and HARDIRQ-irq-unsafe lock:
> [ 2417.747067] -> (&(&mm->unused_lock)->rlock){+.+...} ops: 328035 {
> [ 2417.747072] HARDIRQ-ON-W at:
> [ 2417.747074] [<ffffffff81097418>] __lock_acquire+0x6eb/0x8f4
> [ 2417.747077] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747081] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747084] [<ffffffff8129f641>] drm_mm_pre_get+0x20/0x1a7
> [ 2417.747088] [<ffffffffa00963f2>] ttm_bo_init+0x234/0x385 [ttm]
> [ 2417.747093] [<ffffffffa00b67e4>] nouveau_bo_new+0x366/0x3eb [nouveau]
> [ 2417.747100] [<ffffffffa00ad341>] nouveau_mem_init+0x262/0x44a [nouveau]
> [ 2417.747106] [<ffffffffa00ab8b6>] nouveau_card_init+0xa73/0xd7e [nouveau]
> [ 2417.747112] [<ffffffffa00ac27b>] nouveau_load+0x6ba/0x70a [nouveau]
> [ 2417.747117] [<ffffffff8129b613>] drm_get_dev+0x470/0x5a1
> [ 2417.747121] [<ffffffffa0108b24>] nouveau_pci_probe+0x10/0x12 [nouveau]
> [ 2417.747129] [<ffffffff8121f2c7>] local_pci_probe+0x12/0x16
> [ 2417.747133] [<ffffffff8121faaf>] pci_device_probe+0x60/0x8f
> [ 2417.747136] [<ffffffff812aced7>] driver_probe_device+0xa7/0x136
> [ 2417.747140] [<ffffffff812acfc2>] __driver_attach+0x5c/0x80
> [ 2417.747143] [<ffffffff812ac632>] bus_for_each_dev+0x54/0x89
> [ 2417.747146] [<ffffffff812acd46>] driver_attach+0x19/0x1b
> [ 2417.747149] [<ffffffff812abf48>] bus_add_driver+0x183/0x2ef
> [ 2417.747152] [<ffffffff812ad28f>] driver_register+0x98/0x109
> [ 2417.747156] [<ffffffff8121fd1f>] __pci_register_driver+0x63/0xd3
> [ 2417.747159] [<ffffffff81295f78>] drm_init+0x6b/0xd1
> [ 2417.747162] [<ffffffffa0128048>] 0xffffffffa0128048
> [ 2417.747165] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
> [ 2417.747169] [<ffffffff810a2b0f>] sys_init_module+0x9c/0x1dd
> [ 2417.747172] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.747176] SOFTIRQ-ON-W at:
> [ 2417.747178] [<ffffffff8109743b>] __lock_acquire+0x70e/0x8f4
> [ 2417.747181] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747184] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747188] [<ffffffff8129f641>] drm_mm_pre_get+0x20/0x1a7
> [ 2417.747191] [<ffffffffa00963f2>] ttm_bo_init+0x234/0x385 [ttm]
> [ 2417.747196] [<ffffffffa00b67e4>] nouveau_bo_new+0x366/0x3eb [nouveau]
> [ 2417.747203] [<ffffffffa00ad341>] nouveau_mem_init+0x262/0x44a [nouveau]
> [ 2417.747209] [<ffffffffa00ab8b6>] nouveau_card_init+0xa73/0xd7e [nouveau]
> [ 2417.747215] [<ffffffffa00ac27b>] nouveau_load+0x6ba/0x70a [nouveau]
> [ 2417.747221] [<ffffffff8129b613>] drm_get_dev+0x470/0x5a1
> [ 2417.747224] [<ffffffffa0108b24>] nouveau_pci_probe+0x10/0x12 [nouveau]
> [ 2417.747233] [<ffffffff8121f2c7>] local_pci_probe+0x12/0x16
> [ 2417.747236] [<ffffffff8121faaf>] pci_device_probe+0x60/0x8f
> [ 2417.747239] [<ffffffff812aced7>] driver_probe_device+0xa7/0x136
> [ 2417.747243] [<ffffffff812acfc2>] __driver_attach+0x5c/0x80
> [ 2417.747246] [<ffffffff812ac632>] bus_for_each_dev+0x54/0x89
> [ 2417.747249] [<ffffffff812acd46>] driver_attach+0x19/0x1b
> [ 2417.747252] [<ffffffff812abf48>] bus_add_driver+0x183/0x2ef
> [ 2417.747255] [<ffffffff812ad28f>] driver_register+0x98/0x109
> [ 2417.747259] [<ffffffff8121fd1f>] __pci_register_driver+0x63/0xd3
> [ 2417.747262] [<ffffffff81295f78>] drm_init+0x6b/0xd1
> [ 2417.747265] [<ffffffffa0128048>] 0xffffffffa0128048
> [ 2417.747268] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
> [ 2417.747272] [<ffffffff810a2b0f>] sys_init_module+0x9c/0x1dd
> [ 2417.747275] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.747278] INITIAL USE at:
> [ 2417.747280] [<ffffffff81097494>] __lock_acquire+0x767/0x8f4
> [ 2417.747284] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747287] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747291] [<ffffffff8129f641>] drm_mm_pre_get+0x20/0x1a7
> [ 2417.747294] [<ffffffffa00963f2>] ttm_bo_init+0x234/0x385 [ttm]
> [ 2417.747299] [<ffffffffa00b67e4>] nouveau_bo_new+0x366/0x3eb [nouveau]
> [ 2417.747306] [<ffffffffa00ad341>] nouveau_mem_init+0x262/0x44a [nouveau]
> [ 2417.747312] [<ffffffffa00ab8b6>] nouveau_card_init+0xa73/0xd7e [nouveau]
> [ 2417.747318] [<ffffffffa00ac27b>] nouveau_load+0x6ba/0x70a [nouveau]
> [ 2417.747323] [<ffffffff8129b613>] drm_get_dev+0x470/0x5a1
> [ 2417.747327] [<ffffffffa0108b24>] nouveau_pci_probe+0x10/0x12 [nouveau]
> [ 2417.747335] [<ffffffff8121f2c7>] local_pci_probe+0x12/0x16
> [ 2417.747339] [<ffffffff8121faaf>] pci_device_probe+0x60/0x8f
> [ 2417.747342] [<ffffffff812aced7>] driver_probe_device+0xa7/0x136
> [ 2417.747345] [<ffffffff812acfc2>] __driver_attach+0x5c/0x80
> [ 2417.747349] [<ffffffff812ac632>] bus_for_each_dev+0x54/0x89
> [ 2417.747352] [<ffffffff812acd46>] driver_attach+0x19/0x1b
> [ 2417.747355] [<ffffffff812abf48>] bus_add_driver+0x183/0x2ef
> [ 2417.747358] [<ffffffff812ad28f>] driver_register+0x98/0x109
> [ 2417.747361] [<ffffffff8121fd1f>] __pci_register_driver+0x63/0xd3
> [ 2417.747365] [<ffffffff81295f78>] drm_init+0x6b/0xd1
> [ 2417.747368] [<ffffffffa0128048>] 0xffffffffa0128048
> [ 2417.747371] [<ffffffff810001ef>] do_one_initcall+0x59/0x14e
> [ 2417.747374] [<ffffffff810a2b0f>] sys_init_module+0x9c/0x1dd
> [ 2417.747377] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.747381] }
> [ 2417.747382] ... key at: [<ffffffff8240a6c0>] __key.36424+0x0/0x8
> [ 2417.747386] ... acquired at:
> [ 2417.747387] [<ffffffff81095dea>] check_irq_usage+0x5d/0xbe
> [ 2417.747390] [<ffffffff81096754>] validate_chain+0x74a/0xd23
> [ 2417.747393] [<ffffffff810975b0>] __lock_acquire+0x883/0x8f4
> [ 2417.747396] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747399] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747401] [<ffffffff8129f0c0>] drm_mm_put_block+0x17a/0x1c0
> [ 2417.747405] [<ffffffffa00aed3e>] nouveau_gpuobj_del+0x167/0x1b5 [nouveau]
> [ 2417.747410] [<ffffffffa00af553>] nouveau_gpuobj_ref_del+0x2f3/0x31a [nouveau]
> [ 2417.747416] [<ffffffffa00dc365>] nv50_graph_destroy_context+0xf1/0xfd [nouveau]
> [ 2417.747425] [<ffffffffa00ac534>] nouveau_channel_free+0x141/0x233 [nouveau]
> [ 2417.747430] [<ffffffffa00ac695>] nouveau_ioctl_fifo_free+0x6f/0x73 [nouveau]
> [ 2417.747436] [<ffffffff81295cc2>] drm_ioctl+0x27b/0x347
> [ 2417.747438] [<ffffffff8110c51d>] vfs_ioctl+0x2d/0xa1
> [ 2417.747441] [<ffffffff8110ca69>] do_vfs_ioctl+0x454/0x48d
> [ 2417.747444] [<ffffffff8110cae4>] sys_ioctl+0x42/0x65
> [ 2417.747447] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
> [ 2417.747450]
> [ 2417.747451]
> [ 2417.747451] stack backtrace:
> [ 2417.747454] Pid: 2850, comm: warsow Not tainted 2.6.35-rc4-nv+ #379
> [ 2417.747455] Call Trace:
> [ 2417.747458] [<ffffffff81095d79>] check_usage+0x45c/0x470
> [ 2417.747462] [<ffffffff81095dea>] check_irq_usage+0x5d/0xbe
> [ 2417.747465] [<ffffffff81096754>] validate_chain+0x74a/0xd23
> [ 2417.747468] [<ffffffff810975b0>] __lock_acquire+0x883/0x8f4
> [ 2417.747472] [<ffffffff8129f0c0>] ? drm_mm_put_block+0x17a/0x1c0
> [ 2417.747475] [<ffffffff81097769>] lock_acquire+0x148/0x18d
> [ 2417.747477] [<ffffffff8129f0c0>] ? drm_mm_put_block+0x17a/0x1c0
> [ 2417.747480] [<ffffffff81094fd7>] ? mark_held_locks+0x52/0x70
> [ 2417.747483] [<ffffffff8143b1d9>] _raw_spin_lock+0x36/0x45
> [ 2417.747486] [<ffffffff8129f0c0>] ? drm_mm_put_block+0x17a/0x1c0
> [ 2417.747490] [<ffffffff8129f0c0>] drm_mm_put_block+0x17a/0x1c0
> [ 2417.747496] [<ffffffffa00aed3e>] nouveau_gpuobj_del+0x167/0x1b5 [nouveau]
> [ 2417.747501] [<ffffffffa00af553>] nouveau_gpuobj_ref_del+0x2f3/0x31a [nouveau]
> [ 2417.747510] [<ffffffffa00dc365>] nv50_graph_destroy_context+0xf1/0xfd [nouveau]
> [ 2417.747516] [<ffffffffa00ac534>] nouveau_channel_free+0x141/0x233 [nouveau]
> [ 2417.747519] [<ffffffff8105dcca>] ? add_preempt_count+0x34/0x36
> [ 2417.747525] [<ffffffffa00ac695>] nouveau_ioctl_fifo_free+0x6f/0x73 [nouveau]
> [ 2417.747527] [<ffffffff81295cc2>] drm_ioctl+0x27b/0x347
> [ 2417.747533] [<ffffffffa00ac626>] ? nouveau_ioctl_fifo_free+0x0/0x73 [nouveau]
> [ 2417.747536] [<ffffffff81095382>] ? debug_check_no_locks_freed+0x113/0x129
> [ 2417.747539] [<ffffffff81094fd7>] ? mark_held_locks+0x52/0x70
> [ 2417.747542] [<ffffffff810faaaa>] ? kmem_cache_free+0xb6/0x195
> [ 2417.747545] [<ffffffff8110c51d>] vfs_ioctl+0x2d/0xa1
> [ 2417.747548] [<ffffffff8110ca69>] do_vfs_ioctl+0x454/0x48d
> [ 2417.747551] [<ffffffff810ff4db>] ? fget_light+0xd6/0x289
> [ 2417.747554] [<ffffffff8110cae4>] sys_ioctl+0x42/0x65
> [ 2417.747557] [<ffffffff8102fdab>] system_call_fastpath+0x16/0x1b
>
Hey,
Thanks for the report, I'll look at this more during the week.
> Deadlock scenario looks like this:
> CPU1 CPU2
> nouveau code calls some drm_mm.c
> function which takes mm->unused_lock
>
> nouveau_channel_free disables irqs and takes dev_priv->context_switch_lock
> calls nv50_graph_destroy_context which
> (... backtrace above)
> calls drm_mm_put_block which tries to take mm->unused_lock (spins)
> nouveau interrupt raises
>
> nouveau_irq_handler tries to take
> dev_priv->context_switch_lock (spins)
>
> deadlock
It's important to note that the drm_mm referenced eventually by
nv50_graph_destroy_context is per-channel on the card, so for the
deadlock to happen it'd have to be multiple threads from a single
process, one thread creating/destroying and object on the channel while
another was trying to destroy the channel.
>
> Possible solutions:
> - reverting "drm/nouveau: use drm_mm in preference to custom code doing the same thing"
> - disabling interrupts before calling drm_mm functions - unmaintainable and still
> deadlockable in multicard setups (nouveau and eg radeon)
Agreed it's unmaintainable, but, as mentioned above, the relevant locks
can't be touched by radeon.
> - making mm->unused_lock HARDIRQ-safe (patch below) - simple but with slight overhead
I'll look more during the week, there's other solutions to be explored.
Ben.
>
> ---
> From: Marcin Slusarz <marcin.slusarz at gmail.com>
> Subject: [PATCH] drm: make drm_mm->unused_lock HARDIRQ-safe
>
> nouveau started to use drm_mm functions (in "drm/nouveau: use drm_mm
> in preference to custom code doing the same thing") but it has to call
> them under HARDIRQ-safe lock. To prevent deadlocks we have to make
> drm_mm->unused_lock HARDIRQ-safe too.
>
> Deadlock scenario:
> CPU1 CPU2
> nouveau code calls some drm_mm.c
> function which takes mm->unused_lock
>
> nouveau_channel_free disables irqs and takes dev_priv->context_switch_lock
> calls nv50_graph_destroy_context which
> (... backtrace above)
> calls drm_mm_put_block which tries to take mm->unused_lock (spins)
> nouveau interrupt raises
>
> nouveau_irq_handler tries to take
> dev_priv->context_switch_lock (spins)
>
> Signed-off-by: Marcin Slusarz <marcin.slusarz at gmail.com>
> ---
> drivers/gpu/drm/drm_mm.c | 30 +++++++++++++++++-------------
> 1 files changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mm.c b/drivers/gpu/drm/drm_mm.c
> index 2ac074c..bb95831 100644
> --- a/drivers/gpu/drm/drm_mm.c
> +++ b/drivers/gpu/drm/drm_mm.c
> @@ -81,6 +81,7 @@ int drm_mm_remove_space_from_tail(struct drm_mm *mm, unsigned long size)
> static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
> {
> struct drm_mm_node *child;
> + unsigned long flags;
>
> if (atomic)
> child = kmalloc(sizeof(*child), GFP_ATOMIC);
> @@ -88,7 +89,7 @@ static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
> child = kmalloc(sizeof(*child), GFP_KERNEL);
>
> if (unlikely(child == NULL)) {
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
> if (list_empty(&mm->unused_nodes))
> child = NULL;
> else {
> @@ -98,7 +99,7 @@ static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
> list_del(&child->fl_entry);
> --mm->num_unused;
> }
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> }
> return child;
> }
> @@ -111,22 +112,23 @@ static struct drm_mm_node *drm_mm_kmalloc(struct drm_mm *mm, int atomic)
> int drm_mm_pre_get(struct drm_mm *mm)
> {
> struct drm_mm_node *node;
> + unsigned long flags;
>
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
> while (mm->num_unused < MM_UNUSED_TARGET) {
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> node = kmalloc(sizeof(*node), GFP_KERNEL);
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
>
> if (unlikely(node == NULL)) {
> int ret = (mm->num_unused < 2) ? -ENOMEM : 0;
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> return ret;
> }
> ++mm->num_unused;
> list_add_tail(&node->fl_entry, &mm->unused_nodes);
> }
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> return 0;
> }
> EXPORT_SYMBOL(drm_mm_pre_get);
> @@ -277,6 +279,7 @@ void drm_mm_put_block(struct drm_mm_node *cur)
> struct list_head *root_head = &mm->ml_entry;
> struct drm_mm_node *prev_node = NULL;
> struct drm_mm_node *next_node;
> + unsigned long flags;
>
> int merged = 0;
>
> @@ -296,14 +299,14 @@ void drm_mm_put_block(struct drm_mm_node *cur)
> prev_node->size += next_node->size;
> list_del(&next_node->ml_entry);
> list_del(&next_node->fl_entry);
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
> if (mm->num_unused < MM_UNUSED_TARGET) {
> list_add(&next_node->fl_entry,
> &mm->unused_nodes);
> ++mm->num_unused;
> } else
> kfree(next_node);
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> } else {
> next_node->size += cur->size;
> next_node->start = cur->start;
> @@ -316,13 +319,13 @@ void drm_mm_put_block(struct drm_mm_node *cur)
> list_add(&cur->fl_entry, &mm->fl_entry);
> } else {
> list_del(&cur->ml_entry);
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
> if (mm->num_unused < MM_UNUSED_TARGET) {
> list_add(&cur->fl_entry, &mm->unused_nodes);
> ++mm->num_unused;
> } else
> kfree(cur);
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
> }
> }
>
> @@ -445,6 +448,7 @@ void drm_mm_takedown(struct drm_mm * mm)
> struct list_head *bnode = mm->fl_entry.next;
> struct drm_mm_node *entry;
> struct drm_mm_node *next;
> + unsigned long flags;
>
> entry = list_entry(bnode, struct drm_mm_node, fl_entry);
>
> @@ -458,13 +462,13 @@ void drm_mm_takedown(struct drm_mm * mm)
> list_del(&entry->ml_entry);
> kfree(entry);
>
> - spin_lock(&mm->unused_lock);
> + spin_lock_irqsave(&mm->unused_lock, flags);
> list_for_each_entry_safe(entry, next, &mm->unused_nodes, fl_entry) {
> list_del(&entry->fl_entry);
> kfree(entry);
> --mm->num_unused;
> }
> - spin_unlock(&mm->unused_lock);
> + spin_unlock_irqrestore(&mm->unused_lock, flags);
>
> BUG_ON(mm->num_unused != 0);
> }
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