August 2018 - Linux-stable-mirror

[PATCH v6 3/5] drm/nouveau: Fix deadlock with fb_helper with async RPM requests

by Lyude Paul

I'm sure I don't need to tell you that fb_helper's locking is a mess. That being said; fb_helper's locking mess can seriously complicate the runtime suspend/resume operations of drivers because it can invoke atomic commits and connector probing from anywhere that calls drm_fb_helper_hotplug_event(). Since most drivers use drm_fb_helper_output_poll_changed() as their output_poll_changed handler, this can happen in every single context that can fire off a hotplug event. An example: [ 246.669625] INFO: task kworker/4:0:37 blocked for more than 120 seconds. [ 246.673398] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.675271] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.676527] kworker/4:0 D 0 37 2 0x80000000 [ 246.677580] Workqueue: events output_poll_execute [drm_kms_helper] [ 246.678704] Call Trace: [ 246.679753] __schedule+0x322/0xaf0 [ 246.680916] schedule+0x33/0x90 [ 246.681924] schedule_preempt_disabled+0x15/0x20 [ 246.683023] __mutex_lock+0x569/0x9a0 [ 246.684035] ? kobject_uevent_env+0x117/0x7b0 [ 246.685132] ? drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.686179] mutex_lock_nested+0x1b/0x20 [ 246.687278] ? mutex_lock_nested+0x1b/0x20 [ 246.688307] drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.689420] drm_fb_helper_output_poll_changed+0x23/0x30 [drm_kms_helper] [ 246.690462] drm_kms_helper_hotplug_event+0x2a/0x30 [drm_kms_helper] [ 246.691570] output_poll_execute+0x198/0x1c0 [drm_kms_helper] [ 246.692611] process_one_work+0x231/0x620 [ 246.693725] worker_thread+0x214/0x3a0 [ 246.694756] kthread+0x12b/0x150 [ 246.695856] ? wq_pool_ids_show+0x140/0x140 [ 246.696888] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.697998] ret_from_fork+0x3a/0x50 [ 246.699034] INFO: task kworker/0:1:60 blocked for more than 120 seconds. [ 246.700153] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.701182] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.702278] kworker/0:1 D 0 60 2 0x80000000 [ 246.703293] Workqueue: pm pm_runtime_work [ 246.704393] Call Trace: [ 246.705403] __schedule+0x322/0xaf0 [ 246.706439] ? wait_for_completion+0x104/0x190 [ 246.707393] schedule+0x33/0x90 [ 246.708375] schedule_timeout+0x3a5/0x590 [ 246.709289] ? mark_held_locks+0x58/0x80 [ 246.710208] ? _raw_spin_unlock_irq+0x2c/0x40 [ 246.711222] ? wait_for_completion+0x104/0x190 [ 246.712134] ? trace_hardirqs_on_caller+0xf4/0x190 [ 246.713094] ? wait_for_completion+0x104/0x190 [ 246.713964] wait_for_completion+0x12c/0x190 [ 246.714895] ? wake_up_q+0x80/0x80 [ 246.715727] ? get_work_pool+0x90/0x90 [ 246.716649] flush_work+0x1c9/0x280 [ 246.717483] ? flush_workqueue_prep_pwqs+0x1b0/0x1b0 [ 246.718442] __cancel_work_timer+0x146/0x1d0 [ 246.719247] cancel_delayed_work_sync+0x13/0x20 [ 246.720043] drm_kms_helper_poll_disable+0x1f/0x30 [drm_kms_helper] [ 246.721123] nouveau_pmops_runtime_suspend+0x3d/0xb0 [nouveau] [ 246.721897] pci_pm_runtime_suspend+0x6b/0x190 [ 246.722825] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.723737] __rpm_callback+0x7a/0x1d0 [ 246.724721] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.725607] rpm_callback+0x24/0x80 [ 246.726553] ? pci_has_legacy_pm_support+0x70/0x70 [ 246.727376] rpm_suspend+0x142/0x6b0 [ 246.728185] pm_runtime_work+0x97/0xc0 [ 246.728938] process_one_work+0x231/0x620 [ 246.729796] worker_thread+0x44/0x3a0 [ 246.730614] kthread+0x12b/0x150 [ 246.731395] ? wq_pool_ids_show+0x140/0x140 [ 246.732202] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.732878] ret_from_fork+0x3a/0x50 [ 246.733768] INFO: task kworker/4:2:422 blocked for more than 120 seconds. [ 246.734587] Not tainted 4.18.0-rc5Lyude-Test+ #2 [ 246.735393] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.736113] kworker/4:2 D 0 422 2 0x80000080 [ 246.736789] Workqueue: events_long drm_dp_mst_link_probe_work [drm_kms_helper] [ 246.737665] Call Trace: [ 246.738490] __schedule+0x322/0xaf0 [ 246.739250] schedule+0x33/0x90 [ 246.739908] rpm_resume+0x19c/0x850 [ 246.740750] ? finish_wait+0x90/0x90 [ 246.741541] __pm_runtime_resume+0x4e/0x90 [ 246.742370] nv50_disp_atomic_commit+0x31/0x210 [nouveau] [ 246.743124] drm_atomic_commit+0x4a/0x50 [drm] [ 246.743775] restore_fbdev_mode_atomic+0x1c8/0x240 [drm_kms_helper] [ 246.744603] restore_fbdev_mode+0x31/0x140 [drm_kms_helper] [ 246.745373] drm_fb_helper_restore_fbdev_mode_unlocked+0x54/0xb0 [drm_kms_helper] [ 246.746220] drm_fb_helper_set_par+0x2d/0x50 [drm_kms_helper] [ 246.746884] drm_fb_helper_hotplug_event.part.28+0x96/0xb0 [drm_kms_helper] [ 246.747675] drm_fb_helper_output_poll_changed+0x23/0x30 [drm_kms_helper] [ 246.748544] drm_kms_helper_hotplug_event+0x2a/0x30 [drm_kms_helper] [ 246.749439] nv50_mstm_hotplug+0x15/0x20 [nouveau] [ 246.750111] drm_dp_send_link_address+0x177/0x1c0 [drm_kms_helper] [ 246.750764] drm_dp_check_and_send_link_address+0xa8/0xd0 [drm_kms_helper] [ 246.751602] drm_dp_mst_link_probe_work+0x51/0x90 [drm_kms_helper] [ 246.752314] process_one_work+0x231/0x620 [ 246.752979] worker_thread+0x44/0x3a0 [ 246.753838] kthread+0x12b/0x150 [ 246.754619] ? wq_pool_ids_show+0x140/0x140 [ 246.755386] ? kthread_create_worker_on_cpu+0x70/0x70 [ 246.756162] ret_from_fork+0x3a/0x50 [ 246.756847] Showing all locks held in the system: [ 246.758261] 3 locks held by kworker/4:0/37: [ 246.759016] #0: 00000000f8df4d2d ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.759856] #1: 00000000e6065461 ((work_completion)(&(&dev->mode_config.output_poll_work)->work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.760670] #2: 00000000cb66735f (&helper->lock){+.+.}, at: drm_fb_helper_hotplug_event.part.28+0x20/0xb0 [drm_kms_helper] [ 246.761516] 2 locks held by kworker/0:1/60: [ 246.762274] #0: 00000000fff6be0f ((wq_completion)"pm"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.762982] #1: 000000005ab44fb4 ((work_completion)(&dev->power.work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.763890] 1 lock held by khungtaskd/64: [ 246.764664] #0: 000000008cb8b5c3 (rcu_read_lock){....}, at: debug_show_all_locks+0x23/0x185 [ 246.765588] 5 locks held by kworker/4:2/422: [ 246.766440] #0: 00000000232f0959 ((wq_completion)"events_long"){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.767390] #1: 00000000bb59b134 ((work_completion)(&mgr->work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 246.768154] #2: 00000000cb66735f (&helper->lock){+.+.}, at: drm_fb_helper_restore_fbdev_mode_unlocked+0x4c/0xb0 [drm_kms_helper] [ 246.768966] #3: 000000004c8f0b6b (crtc_ww_class_acquire){+.+.}, at: restore_fbdev_mode_atomic+0x4b/0x240 [drm_kms_helper] [ 246.769921] #4: 000000004c34a296 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_backoff+0x8a/0x1b0 [drm] [ 246.770839] 1 lock held by dmesg/1038: [ 246.771739] 2 locks held by zsh/1172: [ 246.772650] #0: 00000000836d0438 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 246.773680] #1: 000000001f4f4d48 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0xc1/0x870 [ 246.775522] ============================================= After trying dozens of different solutions, I found one very simple one that should also have the benefit of preventing us from having to fight locking for the rest of our lives. So, we work around these deadlocks by deferring all fbcon hotplug events that happen after the runtime suspend process starts until after the device is resumed again. Changes since v5: - Come up with the (hopefully final) solution for solving this dumb problem, one that is a lot less likely to cause issues with locking in the future. This should work around all deadlock conditions with fbcon brought up thus far. Changes since v4: - Add nouveau_fbcon_hotplugged_in_suspend() to workaround deadlock condition that Lukas described - Just move all of this out of drm_fb_helper. It seems that other DRM drivers have already figured out other workarounds for this. If other drivers do end up needing this in the future, we can just move this back into drm_fb_helper again. Changes since v3: - Actually check if fb_helper is NULL in both new helpers - Actually check drm_fbdev_emulation in both new helpers - Don't fire off a fb_helper hotplug unconditionally; only do it if the following conditions are true (as otherwise, calling this in the wrong spot will cause Bad Things to happen): - fb_helper hotplug handling was actually inhibited previously - fb_helper actually has a delayed hotplug pending - fb_helper is actually bound - fb_helper is actually initialized - Add __must_check to drm_fb_helper_suspend_hotplug(). There's no situation where a driver would actually want to use this without checking the return value, so enforce that - Rewrite and clarify the documentation for both helpers. - Make sure to return true in the drm_fb_helper_suspend_hotplug() stub that's provided in drm_fb_helper.h when CONFIG_DRM_FBDEV_EMULATION isn't enabled - Actually grab the toplevel fb_helper lock in drm_fb_helper_resume_hotplug(), since it's possible other activity (such as a hotplug) could be going on at the same time the driver calls drm_fb_helper_resume_hotplug(). We need this to check whether or not drm_fb_helper_hotplug_event() needs to be called anyway Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: stable(a)vger.kernel.org Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Karol Herbst <karolherbst(a)gmail.com> --- drivers/gpu/drm/nouveau/dispnv50/disp.c | 2 +- drivers/gpu/drm/nouveau/nouveau_display.c | 2 +- drivers/gpu/drm/nouveau/nouveau_fbcon.c | 72 +++++++++++++++++++++++ drivers/gpu/drm/nouveau/nouveau_fbcon.h | 7 +++ 4 files changed, 81 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 8b522a9b12f6..a0772389ed90 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -2049,7 +2049,7 @@ nv50_disp_atomic_state_alloc(struct drm_device *dev) static const struct drm_mode_config_funcs nv50_disp_func = { .fb_create = nouveau_user_framebuffer_create, - .output_poll_changed = drm_fb_helper_output_poll_changed, + .output_poll_changed = nouveau_fbcon_output_poll_changed, .atomic_check = nv50_disp_atomic_check, .atomic_commit = nv50_disp_atomic_commit, .atomic_state_alloc = nv50_disp_atomic_state_alloc, diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c index 1d36ab5d4796..4b873e668b26 100644 --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -293,7 +293,7 @@ nouveau_user_framebuffer_create(struct drm_device *dev, static const struct drm_mode_config_funcs nouveau_mode_config_funcs = { .fb_create = nouveau_user_framebuffer_create, - .output_poll_changed = drm_fb_helper_output_poll_changed, + .output_poll_changed = nouveau_fbcon_output_poll_changed, }; diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c b/drivers/gpu/drm/nouveau/nouveau_fbcon.c index 85c1f10bc2b6..c7e86e9232a6 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c @@ -466,6 +466,7 @@ nouveau_fbcon_set_suspend_work(struct work_struct *work) console_unlock(); if (state == FBINFO_STATE_RUNNING) { + nouveau_fbcon_hotplug_resume(drm->fbcon); pm_runtime_mark_last_busy(drm->dev->dev); pm_runtime_put_sync(drm->dev->dev); } @@ -487,6 +488,76 @@ nouveau_fbcon_set_suspend(struct drm_device *dev, int state) schedule_work(&drm->fbcon_work); } +void +nouveau_fbcon_output_poll_changed(struct drm_device *dev) +{ + struct nouveau_drm *drm = nouveau_drm(dev); + struct nouveau_fbdev *fbcon = drm->fbcon; + int ret; + + if (!fbcon) + return; + + mutex_lock(&fbcon->hotplug_lock); + + ret = pm_runtime_get(dev->dev); + if (ret == 1 || ret == -EACCES) { + drm_fb_helper_hotplug_event(&fbcon->helper); + + pm_runtime_mark_last_busy(dev->dev); + pm_runtime_put_autosuspend(dev->dev); + } else if (ret == 0) { + /* If the GPU was already in the process of suspending before + * this event happened, then we can't block here as we'll + * deadlock the runtime pmops since they wait for us to + * finish. So, just defer this event for when we runtime + * resume again. It will be handled by fbcon_work. + */ + NV_DEBUG(drm, "fbcon HPD event deferred until runtime resume\n"); + fbcon->hotplug_waiting = true; + pm_runtime_put_noidle(drm->dev->dev); + } else { + DRM_WARN("fbcon HPD event lost due to RPM failure: %d\n", + ret); + } + + mutex_unlock(&fbcon->hotplug_lock); +} + +void +nouveau_fbcon_hotplug_resume(struct nouveau_fbdev *fbcon) +{ + struct nouveau_drm *drm; + + if (!fbcon) + return; + drm = nouveau_drm(fbcon->helper.dev); + + mutex_lock(&fbcon->hotplug_lock); + if (fbcon->hotplug_waiting) { + fbcon->hotplug_waiting = false; + + NV_DEBUG(drm, "Handling deferred fbcon HPD events\n"); + drm_fb_helper_hotplug_event(&fbcon->helper); + } + mutex_unlock(&fbcon->hotplug_lock); +} + +bool +nouveau_fbcon_hotplugged_in_suspend(struct nouveau_fbdev *fbcon) +{ + bool hotplug; + + if (!fbcon) + return false; + + mutex_lock(&fbcon->hotplug_lock); + hotplug = fbcon->hotplug_waiting; + mutex_unlock(&fbcon->hotplug_lock); + + return hotplug; +} + int nouveau_fbcon_init(struct drm_device *dev) { @@ -505,6 +576,7 @@ nouveau_fbcon_init(struct drm_device *dev) drm->fbcon = fbcon; INIT_WORK(&drm->fbcon_work, nouveau_fbcon_set_suspend_work); + mutex_init(&fbcon->hotplug_lock); drm_fb_helper_prepare(dev, &fbcon->helper, &nouveau_fbcon_helper_funcs); diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.h b/drivers/gpu/drm/nouveau/nouveau_fbcon.h index a6f192ea3fa6..148c6b2cc6da 100644 --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.h +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.h @@ -41,6 +41,9 @@ struct nouveau_fbdev { struct nvif_object gdi; struct nvif_object blit; struct nvif_object twod; + + struct mutex hotplug_lock; + bool hotplug_waiting; }; void nouveau_fbcon_restore(void); @@ -68,6 +71,10 @@ void nouveau_fbcon_set_suspend(struct drm_device *dev, int state); void nouveau_fbcon_accel_save_disable(struct drm_device *dev); void nouveau_fbcon_accel_restore(struct drm_device *dev); +void nouveau_fbcon_output_poll_changed(struct drm_device *dev); +void nouveau_fbcon_hotplug_resume(struct nouveau_fbdev *fbcon); +bool nouveau_fbcon_hotplugged_in_suspend(struct nouveau_fbdev *fbcon); + extern int nouveau_nofbaccel; #endif /* __NV50_FBCON_H__ */ -- 2.17.1

6 years, 9 months

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Targeted Amazon Web Services/ Microsoft Azure Global Accounts

by heather.peterson＠laytheon.com

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6 years, 9 months

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[PATCH v6 5/5] drm/nouveau: Fix deadlocks in nouveau_connector_detect()

by Lyude Paul

When we disable hotplugging on the GPU, we need to be able to synchronize with each connector's hotplug interrupt handler before the interrupt is finally disabled. This can be a problem however, since nouveau_connector_detect() currently grabs a runtime power reference when handling connector probing. This will deadlock the runtime suspend handler like so: [ 861.480896] INFO: task kworker/0:2:61 blocked for more than 120 seconds. [ 861.483290] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.485158] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.486332] kworker/0:2 D 0 61 2 0x80000000 [ 861.487044] Workqueue: events nouveau_display_hpd_work [nouveau] [ 861.487737] Call Trace: [ 861.488394] __schedule+0x322/0xaf0 [ 861.489070] schedule+0x33/0x90 [ 861.489744] rpm_resume+0x19c/0x850 [ 861.490392] ? finish_wait+0x90/0x90 [ 861.491068] __pm_runtime_resume+0x4e/0x90 [ 861.491753] nouveau_display_hpd_work+0x22/0x60 [nouveau] [ 861.492416] process_one_work+0x231/0x620 [ 861.493068] worker_thread+0x44/0x3a0 [ 861.493722] kthread+0x12b/0x150 [ 861.494342] ? wq_pool_ids_show+0x140/0x140 [ 861.494991] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.495648] ret_from_fork+0x3a/0x50 [ 861.496304] INFO: task kworker/6:2:320 blocked for more than 120 seconds. [ 861.496968] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.497654] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.498341] kworker/6:2 D 0 320 2 0x80000080 [ 861.499045] Workqueue: pm pm_runtime_work [ 861.499739] Call Trace: [ 861.500428] __schedule+0x322/0xaf0 [ 861.501134] ? wait_for_completion+0x104/0x190 [ 861.501851] schedule+0x33/0x90 [ 861.502564] schedule_timeout+0x3a5/0x590 [ 861.503284] ? mark_held_locks+0x58/0x80 [ 861.503988] ? _raw_spin_unlock_irq+0x2c/0x40 [ 861.504710] ? wait_for_completion+0x104/0x190 [ 861.505417] ? trace_hardirqs_on_caller+0xf4/0x190 [ 861.506136] ? wait_for_completion+0x104/0x190 [ 861.506845] wait_for_completion+0x12c/0x190 [ 861.507555] ? wake_up_q+0x80/0x80 [ 861.508268] flush_work+0x1c9/0x280 [ 861.508990] ? flush_workqueue_prep_pwqs+0x1b0/0x1b0 [ 861.509735] nvif_notify_put+0xb1/0xc0 [nouveau] [ 861.510482] nouveau_display_fini+0xbd/0x170 [nouveau] [ 861.511241] nouveau_display_suspend+0x67/0x120 [nouveau] [ 861.511969] nouveau_do_suspend+0x5e/0x2d0 [nouveau] [ 861.512715] nouveau_pmops_runtime_suspend+0x47/0xb0 [nouveau] [ 861.513435] pci_pm_runtime_suspend+0x6b/0x180 [ 861.514165] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.514897] __rpm_callback+0x7a/0x1d0 [ 861.515618] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.516313] rpm_callback+0x24/0x80 [ 861.517027] ? pci_has_legacy_pm_support+0x70/0x70 [ 861.517741] rpm_suspend+0x142/0x6b0 [ 861.518449] pm_runtime_work+0x97/0xc0 [ 861.519144] process_one_work+0x231/0x620 [ 861.519831] worker_thread+0x44/0x3a0 [ 861.520522] kthread+0x12b/0x150 [ 861.521220] ? wq_pool_ids_show+0x140/0x140 [ 861.521925] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.522622] ret_from_fork+0x3a/0x50 [ 861.523299] INFO: task kworker/6:0:1329 blocked for more than 120 seconds. [ 861.523977] Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.524644] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 861.525349] kworker/6:0 D 0 1329 2 0x80000000 [ 861.526073] Workqueue: events nvif_notify_work [nouveau] [ 861.526751] Call Trace: [ 861.527411] __schedule+0x322/0xaf0 [ 861.528089] schedule+0x33/0x90 [ 861.528758] rpm_resume+0x19c/0x850 [ 861.529399] ? finish_wait+0x90/0x90 [ 861.530073] __pm_runtime_resume+0x4e/0x90 [ 861.530798] nouveau_connector_detect+0x7e/0x510 [nouveau] [ 861.531459] ? ww_mutex_lock+0x47/0x80 [ 861.532097] ? ww_mutex_lock+0x47/0x80 [ 861.532819] ? drm_modeset_lock+0x88/0x130 [drm] [ 861.533481] drm_helper_probe_detect_ctx+0xa0/0x100 [drm_kms_helper] [ 861.534127] drm_helper_hpd_irq_event+0xa4/0x120 [drm_kms_helper] [ 861.534940] nouveau_connector_hotplug+0x98/0x120 [nouveau] [ 861.535556] nvif_notify_work+0x2d/0xb0 [nouveau] [ 861.536221] process_one_work+0x231/0x620 [ 861.536994] worker_thread+0x44/0x3a0 [ 861.537757] kthread+0x12b/0x150 [ 861.538463] ? wq_pool_ids_show+0x140/0x140 [ 861.539102] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.539815] ret_from_fork+0x3a/0x50 [ 861.540521] Showing all locks held in the system: [ 861.541696] 2 locks held by kworker/0:2/61: [ 861.542406] #0: 000000002dbf8af5 ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.543071] #1: 0000000076868126 ((work_completion)(&drm->hpd_work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.543814] 1 lock held by khungtaskd/64: [ 861.544535] #0: 0000000059db4b53 (rcu_read_lock){....}, at: debug_show_all_locks+0x23/0x185 [ 861.545160] 3 locks held by kworker/6:2/320: [ 861.545896] #0: 00000000d9e1bc59 ((wq_completion)"pm"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.546702] #1: 00000000c9f92d84 ((work_completion)(&dev->power.work)){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.547443] #2: 000000004afc5de1 (drm_connector_list_iter){.+.+}, at: nouveau_display_fini+0x96/0x170 [nouveau] [ 861.548146] 1 lock held by dmesg/983: [ 861.548889] 2 locks held by zsh/1250: [ 861.549605] #0: 00000000348e3cf6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 [ 861.550393] #1: 000000007009a7a8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0xc1/0x870 [ 861.551122] 6 locks held by kworker/6:0/1329: [ 861.551957] #0: 000000002dbf8af5 ((wq_completion)"events"){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.552765] #1: 00000000ddb499ad ((work_completion)(&notify->work)#2){+.+.}, at: process_one_work+0x1b3/0x620 [ 861.553582] #2: 000000006e013cbe (&dev->mode_config.mutex){+.+.}, at: drm_helper_hpd_irq_event+0x6c/0x120 [drm_kms_helper] [ 861.554357] #3: 000000004afc5de1 (drm_connector_list_iter){.+.+}, at: drm_helper_hpd_irq_event+0x78/0x120 [drm_kms_helper] [ 861.555227] #4: 0000000044f294d9 (crtc_ww_class_acquire){+.+.}, at: drm_helper_probe_detect_ctx+0x3d/0x100 [drm_kms_helper] [ 861.556133] #5: 00000000db193642 (crtc_ww_class_mutex){+.+.}, at: drm_modeset_lock+0x4b/0x130 [drm] [ 861.557864] ============================================= [ 861.559507] NMI backtrace for cpu 2 [ 861.560363] CPU: 2 PID: 64 Comm: khungtaskd Tainted: G O 4.18.0-rc6Lyude-Test+ #1 [ 861.561197] Hardware name: LENOVO 20EQS64N0B/20EQS64N0B, BIOS N1EET78W (1.51 ) 05/18/2018 [ 861.561948] Call Trace: [ 861.562757] dump_stack+0x8e/0xd3 [ 861.563516] nmi_cpu_backtrace.cold.3+0x14/0x5a [ 861.564269] ? lapic_can_unplug_cpu.cold.27+0x42/0x42 [ 861.565029] nmi_trigger_cpumask_backtrace+0xa1/0xae [ 861.565789] arch_trigger_cpumask_backtrace+0x19/0x20 [ 861.566558] watchdog+0x316/0x580 [ 861.567355] kthread+0x12b/0x150 [ 861.568114] ? reset_hung_task_detector+0x20/0x20 [ 861.568863] ? kthread_create_worker_on_cpu+0x70/0x70 [ 861.569598] ret_from_fork+0x3a/0x50 [ 861.570370] Sending NMI from CPU 2 to CPUs 0-1,3-7: [ 861.571426] NMI backtrace for cpu 6 skipped: idling at intel_idle+0x7f/0x120 [ 861.571429] NMI backtrace for cpu 7 skipped: idling at intel_idle+0x7f/0x120 [ 861.571432] NMI backtrace for cpu 3 skipped: idling at intel_idle+0x7f/0x120 [ 861.571464] NMI backtrace for cpu 5 skipped: idling at intel_idle+0x7f/0x120 [ 861.571467] NMI backtrace for cpu 0 skipped: idling at intel_idle+0x7f/0x120 [ 861.571469] NMI backtrace for cpu 4 skipped: idling at intel_idle+0x7f/0x120 [ 861.571472] NMI backtrace for cpu 1 skipped: idling at intel_idle+0x7f/0x120 [ 861.572428] Kernel panic - not syncing: hung_task: blocked tasks So: fix this by making it so that normal hotplug handling /only/ happens so long as the GPU is currently awake without any pending runtime PM requests. In the event that a hotplug occurs while the device is suspending or resuming, we can simply defer our response until the GPU is fully runtime resumed again. Changes since v5: - Use a new trick I came up with using pm_runtime_get() instead of the hackish junk we had before Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: stable(a)vger.kernel.org Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Karol Herbst <karolherbst(a)gmail.com> --- drivers/gpu/drm/nouveau/nouveau_connector.c | 22 +++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c index 010d6db14cba..109240c03357 100644 --- a/drivers/gpu/drm/nouveau/nouveau_connector.c +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c @@ -1124,6 +1124,26 @@ nouveau_connector_hotplug(struct nvif_notify *notify) const struct nvif_notify_conn_rep_v0 *rep = notify->data; const char *name = connector->name; struct nouveau_encoder *nv_encoder; + int ret; + + ret = pm_runtime_get(drm->dev->dev); + if (ret == 0) { + /* We can't block here if there's a pending PM request + * running, as we'll deadlock nouveau_display_fini() when it + * calls nvif_put() on our nvif_notify struct. So, simply + * defer the hotplug event until the device finishes resuming + */ + NV_DEBUG(drm, "Deferring HPD on %s until runtime resume\n", + name); + schedule_work(&drm->hpd_work); + + pm_runtime_put_noidle(drm->dev->dev); + return NVIF_NOTIFY_KEEP; + } else if (ret != 1 && ret != -EACCES) { + NV_WARN(drm, "HPD on %s dropped due to RPM failure: %d\n", + name, ret); + return NVIF_NOTIFY_DROP; + } if (rep->mask & NVIF_NOTIFY_CONN_V0_IRQ) { NV_DEBUG(drm, "service %s\n", name); @@ -1141,6 +1161,8 @@ nouveau_connector_hotplug(struct nvif_notify *notify) drm_helper_hpd_irq_event(connector->dev); } + pm_runtime_mark_last_busy(drm->dev->dev); + pm_runtime_put_autosuspend(drm->dev->dev); return NVIF_NOTIFY_KEEP; } -- 2.17.1

6 years, 9 months

1
0
0 0

[PATCH v6 4/5] drm/nouveau: Use pm_runtime_get_noresume() in connector_detect()

by Lyude Paul

It's true we can't resume the device from poll workers in nouveau_connector_detect(). We can however, prevent the autosuspend timer from elapsing immediately if it hasn't already without risking any sort of deadlock with the runtime suspend/resume operations. So do that instead of entirely avoiding grabbing a power reference. Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: stable(a)vger.kernel.org Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Karol Herbst <karolherbst(a)gmail.com> --- drivers/gpu/drm/nouveau/nouveau_connector.c | 20 +++++++++++--------- 1 file changed, 11 insertions(+), 9 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_connector.c b/drivers/gpu/drm/nouveau/nouveau_connector.c index 2a45b4c2ceb0..010d6db14cba 100644 --- a/drivers/gpu/drm/nouveau/nouveau_connector.c +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c @@ -572,12 +572,16 @@ nouveau_connector_detect(struct drm_connector *connector, bool force) nv_connector->edid = NULL; } - /* Outputs are only polled while runtime active, so acquiring a - * runtime PM ref here is unnecessary (and would deadlock upon - * runtime suspend because it waits for polling to finish). + /* Outputs are only polled while runtime active, so resuming the + * device here is unnecessary (and would deadlock upon runtime suspend + * because it waits for polling to finish). We do however, want to + * prevent the autosuspend timer from elapsing during this operation + * if possible. */ - if (!drm_kms_helper_is_poll_worker()) { - ret = pm_runtime_get_sync(connector->dev->dev); + if (drm_kms_helper_is_poll_worker()) { + pm_runtime_get_noresume(dev->dev); + } else { + ret = pm_runtime_get_sync(dev->dev); if (ret < 0 && ret != -EACCES) return conn_status; } @@ -655,10 +659,8 @@ nouveau_connector_detect(struct drm_connector *connector, bool force) out: - if (!drm_kms_helper_is_poll_worker()) { - pm_runtime_mark_last_busy(connector->dev->dev); - pm_runtime_put_autosuspend(connector->dev->dev); - } + pm_runtime_mark_last_busy(dev->dev); + pm_runtime_put_autosuspend(dev->dev); return conn_status; } -- 2.17.1

6 years, 9 months

1
0
0 0

[PATCH v6 2/5] drm/nouveau: Remove duplicate poll_enable() in pmops_runtime_suspend()

by Lyude Paul

Since actual hotplug notifications don't get disabled until nouveau_display_fini() is called, all this will do is cause any hotplugs that happen between this drm_kms_helper_poll_disable() call and the actual hotplug disablement to potentially be dropped if ACPI isn't around to help us. Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: stable(a)vger.kernel.org Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Karol Herbst <karolherbst(a)gmail.com> --- drivers/gpu/drm/nouveau/nouveau_drm.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c index c7ec86d6c3c9..5fdc1fbe2ee5 100644 --- a/drivers/gpu/drm/nouveau/nouveau_drm.c +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c @@ -835,7 +835,6 @@ nouveau_pmops_runtime_suspend(struct device *dev) return -EBUSY; } - drm_kms_helper_poll_disable(drm_dev); nouveau_switcheroo_optimus_dsm(); ret = nouveau_do_suspend(drm_dev, true); pci_save_state(pdev); -- 2.17.1

6 years, 9 months

1
0
0 0

[PATCH v6 1/5] drm/nouveau: Fix bogus drm_kms_helper_poll_enable() placement

by Lyude Paul

Turns out this part is my fault for not noticing when reviewing 9a2eba337cace ("drm/nouveau: Fix drm poll_helper handling"). Currently we call drm_kms_helper_poll_enable() from nouveau_display_hpd_work(). This makes basically no sense however, because that means we're calling drm_kms_helper_poll_enable() every time we schedule the hotplug detection work. This is also against the advice mentioned in drm_kms_helper_poll_enable()'s documentation: Note that calls to enable and disable polling must be strictly ordered, which is automatically the case when they're only call from suspend/resume callbacks. Of course, hotplugs can't really be ordered. They could even happen immediately after we called drm_kms_helper_poll_disable() in nouveau_display_fini(), which can lead to all sorts of issues. Additionally; enabling polling /after/ we call drm_helper_hpd_irq_event() could also mean that we'd miss a hotplug event anyway, since drm_helper_hpd_irq_event() wouldn't bother trying to probe connectors so long as polling is disabled. So; simply move this back into nouveau_display_init() again. The race condition that both of these patches attempted to work around has already been fixed properly in d61a5c106351 ("drm/nouveau: Fix deadlock on runtime suspend") Fixes: 9a2eba337cace ("drm/nouveau: Fix drm poll_helper handling") Signed-off-by: Lyude Paul <lyude(a)redhat.com> Cc: Lukas Wunner <lukas(a)wunner.de> Cc: Peter Ujfalusi <peter.ujfalusi(a)ti.com> Cc: stable(a)vger.kernel.org --- drivers/gpu/drm/nouveau/nouveau_display.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c b/drivers/gpu/drm/nouveau/nouveau_display.c index ec7861457b84..1d36ab5d4796 100644 --- a/drivers/gpu/drm/nouveau/nouveau_display.c +++ b/drivers/gpu/drm/nouveau/nouveau_display.c @@ -355,8 +355,6 @@ nouveau_display_hpd_work(struct work_struct *work) pm_runtime_get_sync(drm->dev->dev); drm_helper_hpd_irq_event(drm->dev); - /* enable polling for external displays */ - drm_kms_helper_poll_enable(drm->dev); pm_runtime_mark_last_busy(drm->dev->dev); pm_runtime_put_sync(drm->dev->dev); @@ -411,6 +409,11 @@ nouveau_display_init(struct drm_device *dev) if (ret) return ret; + /* enable connector detection and polling for connectors without HPD + * support + */ + drm_kms_helper_poll_enable(dev); + /* enable hotplug interrupts */ drm_connector_list_iter_begin(dev, &conn_iter); nouveau_for_each_non_mst_connector_iter(connector, &conn_iter) { -- 2.17.1

6 years, 9 months

1
0
0 0

[PATCH 2/2] net: socket: Fix potential spectre v1 gadget in sock_is_registered

by Jeremy Cline

'family' can be a user-controlled value, so sanitize it after the bounds check to avoid speculative out-of-bounds access. Cc: Josh Poimboeuf <jpoimboe(a)redhat.com> Cc: stable(a)vger.kernel.org Signed-off-by: Jeremy Cline <jcline(a)redhat.com> --- net/socket.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/socket.c b/net/socket.c index f15d5cbb3ba4..608e29ae6baf 100644 --- a/net/socket.c +++ b/net/socket.c @@ -2672,7 +2672,8 @@ EXPORT_SYMBOL(sock_unregister); bool sock_is_registered(int family) { - return family < NPROTO && rcu_access_pointer(net_families[family]); + return family < NPROTO && + rcu_access_pointer(net_families[array_index_nospec(family, NPROTO)]); } static int __init sock_init(void) -- 2.17.1

6 years, 9 months

2
4
0 0

[PATCH v2 1/2] block: Introduce alloc_disk_node_attr()

by Bart Van Assche

This patch does not change the behavior of any existing code but introduces a function that will be used by the next patch. Signed-off-by: Bart Van Assche <bart.vanassche(a)wdc.com> Cc: Keith Busch <keith.busch(a)intel.com> Cc: Christoph Hellwig <hch(a)lst.de> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: Sagi Grimberg <sagi(a)grimberg.me> Cc: Matias Bjorling <mb(a)lightnvm.io> Cc: <stable(a)vger.kernel.org> --- block/genhd.c | 26 ++++++++++++++++++++++++-- include/linux/genhd.h | 13 +++++++++++-- 2 files changed, 35 insertions(+), 4 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 8cc719a37b32..3b643152907d 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -1413,10 +1413,20 @@ dev_t blk_lookup_devt(const char *name, int partno) } EXPORT_SYMBOL(blk_lookup_devt); -struct gendisk *__alloc_disk_node(int minors, int node_id) +/** + * __alloc_disk_node - allocate a gendisk structure and initialize it + * @minors: number of partitions to allocate memory for + * @node_id: NUMA node to allocate memory from + * @ag: NULL or pointer to a NULL-terminated array with attribute groups that + * must be attached to the disk_to_dev() of the allocated disk structure + */ +struct gendisk *__alloc_disk_node(int minors, int node_id, + const struct attribute_group **ag) { struct gendisk *disk; struct disk_part_tbl *ptbl; + const struct attribute_group **agp; + int num_groups = 0; if (minors > DISK_MAX_PARTS) { printk(KERN_ERR @@ -1425,7 +1435,15 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) minors = DISK_MAX_PARTS; } - disk = kzalloc_node(sizeof(struct gendisk), GFP_KERNEL, node_id); + if (ag) { + for (agp = ag; *agp; agp++) + num_groups++; + /* Only count the terminating NULL if the array is not empty. */ + if (num_groups) + num_groups++; + } + disk = kzalloc_node(struct_size(disk, ag, num_groups), GFP_KERNEL, + node_id); if (disk) { if (!init_part_stats(&disk->part0)) { kfree(disk); @@ -1461,6 +1479,10 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) rand_initialize_disk(disk); disk_to_dev(disk)->class = &block_class; disk_to_dev(disk)->type = &disk_type; + if (num_groups) { + memcpy(disk->ag, ag, num_groups * sizeof(ag)); + disk_to_dev(disk)->groups = disk->ag; + } device_initialize(disk_to_dev(disk)); } return disk; diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 57864422a2c8..50ab6cf77fdf 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -211,6 +211,11 @@ struct gendisk { int node_id; struct badblocks *bb; struct lockdep_map lockdep_map; + /* + * Storage space for NULL-terminated attribute group array for + * disk_to_dev() of this gendisk structure. + */ + const struct attribute_group *ag[0]; }; static inline struct gendisk *part_to_disk(struct hd_struct *part) @@ -608,7 +613,8 @@ extern void __delete_partition(struct percpu_ref *); extern void delete_partition(struct gendisk *, int); extern void printk_all_partitions(void); -extern struct gendisk *__alloc_disk_node(int minors, int node_id); +extern struct gendisk *__alloc_disk_node(int minors, int node_id, + const struct attribute_group **ag); extern struct kobject *get_disk_and_module(struct gendisk *disk); extern void put_disk(struct gendisk *disk); extern void put_disk_and_module(struct gendisk *disk); @@ -634,6 +640,9 @@ extern ssize_t part_fail_store(struct device *dev, #endif /* CONFIG_FAIL_MAKE_REQUEST */ #define alloc_disk_node(minors, node_id) \ + alloc_disk_node_attr(minors, node_id, NULL) + +#define alloc_disk_node_attr(minors, node_id, ag) \ ({ \ static struct lock_class_key __key; \ const char *__name; \ @@ -641,7 +650,7 @@ extern ssize_t part_fail_store(struct device *dev, \ __name = "(gendisk_completion)"#minors"("#node_id")"; \ \ - __disk = __alloc_disk_node(minors, node_id); \ + __disk = __alloc_disk_node(minors, node_id, ag); \ \ if (__disk) \ lockdep_init_map(&__disk->lockdep_map, __name, &__key, 0); \ -- 2.18.0

6 years, 9 months

2
1
0 0

[PATCH 0/3 stable 4.9] proc/sysctl: prune stale dentries during unregistering

by Mike Rapoport

Hi, These patches fix a memory leak in per-cpu areas in v4.9.y The following command sequence while :; do c=$(docker create busybox) docker start $c docker stop $c docker rm $c done causes the number of pcpu_get_vm_area entries in /proc/vmallocinfo to grow. The commit d6cffbbe9a7e ("proc/sysctl: prune stale dentries during unregistering") fixes the issue and the commits ace0c791e6c3 ("proc/sysctl: Don't grab i_lock under sysctl_lock.") and 2fd1d2c4ceb2 ("proc: Fix proc_sys_prune_dcache to hold a sb reference") are the follow-up fixups. I've also checked v4.4 and the issue does not appear there. Eric W. Biederman (2): proc/sysctl: Don't grab i_lock under sysctl_lock. proc: Fix proc_sys_prune_dcache to hold a sb reference Konstantin Khlebnikov (1): proc/sysctl: prune stale dentries during unregistering fs/proc/inode.c | 3 +- fs/proc/internal.h | 7 +++-- fs/proc/proc_sysctl.c | 83 +++++++++++++++++++++++++++++++++++++++----------- include/linux/sysctl.h | 1 + 4 files changed, 74 insertions(+), 20 deletions(-) -- 2.7.4

6 years, 9 months

2
8
0 0

[PATCH for-4.14.y 1/5] mtd: nand: qcom: Add a NULL check for devm_kasprintf()

by Amit Pundir

From: Fabio Estevam <fabio.estevam(a)nxp.com> commit 069f05346d01e7298939f16533953cdf52370be3 upstream. devm_kasprintf() may fail, so we should better add a NULL check and propagate an error on failure. Signed-off-by: Fabio Estevam <fabio.estevam(a)nxp.com> Signed-off-by: Boris Brezillon <boris.brezillon(a)free-electrons.com> Signed-off-by: Amit Pundir <amit.pundir(a)linaro.org> --- Cherry-picked from lede tree https://git.lede-project.org/?p=source.git Please apply it on 4.9.y as well. Not applicable for 4.4.y and 3.18.y drivers/mtd/nand/qcom_nandc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/mtd/nand/qcom_nandc.c b/drivers/mtd/nand/qcom_nandc.c index 3baddfc997d1..b49ca02b399d 100644 --- a/drivers/mtd/nand/qcom_nandc.c +++ b/drivers/mtd/nand/qcom_nandc.c @@ -2544,6 +2544,9 @@ static int qcom_nand_host_init(struct qcom_nand_controller *nandc, nand_set_flash_node(chip, dn); mtd->name = devm_kasprintf(dev, GFP_KERNEL, "qcom_nand.%d", host->cs); + if (!mtd->name) + return -ENOMEM; + mtd->owner = THIS_MODULE; mtd->dev.parent = dev; -- 2.7.4

6 years, 9 months

2
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Linux-stable-mirror August 2018