On most systems with ACPI hotplugging support, it seems that we always
receive a hotplug event once we re-enable EC interrupts even if the GPU
hasn't even been resumed yet.

This can cause problems since even though we schedule hpd_work to handle
connector reprobing for us, hpd_work synchronizes on
pm_runtime_get_sync() to wait until the device is ready to perform
reprobing. Since runtime suspend/resume callbacks are disabled before
the PM core calls ->suspend(), any calls to pm_runtime_get_sync() during
this period will grab a runtime PM ref and return immediately with
-EACCES. Because we schedule hpd_work from our ACPI HPD handler, and
hpd_work synchronizes on pm_runtime_get_sync(), this causes us to launch
a connector reprobe immediately even if the GPU isn't actually resumed
just yet. This causes various warnings in dmesg and occasionally, also
prevents some displays connected to the dedicated GPU from coming back
up after suspend. Example:

usb 1-4: USB disconnect, device number 14
usb 1-4.1: USB disconnect, device number 15
WARNING: CPU: 0 PID: 838 at drivers/gpu/drm/nouveau/include/nvkm/subdev/i2c.h:170 nouveau_dp_detect+0x17e/0x370 [nouveau]
CPU: 0 PID: 838 Comm: kworker/0:6 Not tainted 4.17.14-201.Lyude.bz1477182.V3.fc28.x86_64 #1
Hardware name: LENOVO 20EQS64N00/20EQS64N00, BIOS N1EET77W (1.50 ) 03/28/2018
Workqueue: events nouveau_display_hpd_work [nouveau]
RIP: 0010:nouveau_dp_detect+0x17e/0x370 [nouveau]
RSP: 0018:ffffa15143933cf0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8cb4f656c400 RCX: 0000000000000000
RDX: ffffa1514500e4e4 RSI: ffffa1514500e4e4 RDI: 0000000001009002
RBP: ffff8cb4f4a8a800 R08: ffffa15143933cfd R09: ffffa15143933cfc
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8cb4fb57a000
R13: ffff8cb4fb57a000 R14: ffff8cb4f4a8f800 R15: ffff8cb4f656c418
FS:  0000000000000000(0000) GS:ffff8cb51f400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f78ec938000 CR3: 000000073720a003 CR4: 00000000003606f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ? _cond_resched+0x15/0x30
 nouveau_connector_detect+0x2ce/0x520 [nouveau]
 ? _cond_resched+0x15/0x30
 ? ww_mutex_lock+0x12/0x40
 drm_helper_probe_detect_ctx+0x8b/0xe0 [drm_kms_helper]
 drm_helper_hpd_irq_event+0xa8/0x120 [drm_kms_helper]
 nouveau_display_hpd_work+0x2a/0x60 [nouveau]
 process_one_work+0x187/0x340
 worker_thread+0x2e/0x380
 ? pwq_unbound_release_workfn+0xd0/0xd0
 kthread+0x112/0x130
 ? kthread_create_worker_on_cpu+0x70/0x70
 ret_from_fork+0x35/0x40
Code: 4c 8d 44 24 0d b9 00 05 00 00 48 89 ef ba 09 00 00 00 be 01 00 00 00 e8 e1 09 f8 ff 85 c0 0f 85 b2 01 00 00 80 7c 24 0c 03 74 02 <0f> 0b 48 89 ef e8 b8 07 f8 ff f6 05 51 1b c8 ff 02 0f 84 72 ff
---[ end trace 55d811b38fc8e71a ]---

So, to fix this we attempt to grab a runtime PM reference in the ACPI
handler itself asynchronously. If the GPU is already awake (it will have
normal hotplugging at this point) or runtime PM callbacks are currently
disabled on the device, we drop our reference without updating the
autosuspend delay. We only schedule connector reprobes when we
successfully managed to queue up a resume request with our asynchronous
PM ref.

This also has the added benefit of preventing redundant connector
reprobes from ACPI while the GPU is runtime resumed!
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Karol Herbst <kherbst@redhat.com>
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1477182#c41Signed-off-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

When probing a new MST device, it's not safe to make any assumptions
about it's current state. While most well mannered MST hubs will just
disable the branching unit on hotplug disconnects, this isn't enough to
save us from various other scenarios that might have resulted in
something writing to the MST branching unit before we got control of it.
This could happen if a previous probe we tried failed, if we're booting
in kexec context and the hub is still in the state the last kernel put
it in, etc.

Luckily; there is no reason we can't just reset the branching unit
every time we enable a new topology. So, fix this by resetting it on
enabling new topologies to ensure that we always start off with a clean,
unmodified topology state on MST sinks.

This fixes occasional hard-lockups on my P50's laptop dock (e.g. AUX
times out all DPCD trasactions) observed after multiple docks, undocks,
and module reloads.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Currently, nouveau will re-write the DP_MSTM_CTRL register for an MST
hub every time it receives a long HPD pulse on DP. This isn't actually
necessary and additionally, has some unintended side effects.

With the P50 I've got here, rewriting DP_MSTM_CTRL constantly seems to
make it rather likely (1 out of 5 times usually) that bringing up MST
with it's ThinkPad dock will fail and result in sideband messages timing
out in the middle. Afterwards, successive probes don't manage to get the
dock to communicate properly over MST sideband properly.

Many times sideband message timeouts from MST hubs are indicative of
either the source or the sink dropping an ESI event, which can cause
DRM's perspective of the topology's current state to go out of sync with
reality. While it's tough to really know for sure what's happening to
the dock, using userspace tools to write to DP_MSTM_CTRL in the middle
of the MST link probing process does appear to make things flaky. It's
possible that when we write to DP_MSTM_CTRL, the function that gets
triggered to respond in the dock's firmware temporarily puts it in a
state where it might end up not reporting an ESI to the source, or ends
up dropping a sideband message we sent it.

So, to fix this we make it so that when probing an MST topology, we
respect it's current state. If the dock's already enabled, we simply
read DP_MSTM_CTRL and disable the topology if it's value is not what we
expected. Otherwise, we perform the normal MST probing dance. We avoid
taking any action except if the state of the MST topology actually
changes.

This fixes MST sideband message timeouts and detection failures on my
P50 with its ThinkPad dock.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Cc: Karol Herbst <karolherbst@gmail.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Again, this doesn't do anything. drm_kms_helper_poll_enable() will have
already been called in nouveau_display_init()
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

This won't do anything but potentially make us miss hotplugs. We already
call drm_kms_helper_poll_disable() in
nouveau_pmops_suspend()->nouveau_display_suspend()->nouveau_display_fini()
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

This doesn't do anything, drm_kms_helper_poll_enable() gets called in
nouveau_pmops_resume()->nouveau_display_resume()->nouveau_display_init()
already.
Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

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 v4:
- 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@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

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@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Currently, nouveau uses the generic drm_fb_helper_output_poll_changed()
function provided by DRM as it's output_poll_changed callback.
Unfortunately however, this function doesn't grab runtime PM references
early enough and even if it did-we can't block waiting for the device to
resume in output_poll_changed() since it's very likely that we'll need
to grab the fb_helper lock at some point during the runtime resume
process. This currently results in deadlocking like so:

[  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 v7:
 - Fixup commit message - Daniel Vetter

Changes since v6:
 - Remove unused nouveau_fbcon_hotplugged_in_suspend() - Ilia

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@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

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@redhat.com>
Acked-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: stable@vger.kernel.org
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Turns out this part is my fault for not noticing when reviewing
9a2eba33 ("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

  d61a5c10 ("drm/nouveau: Fix deadlock on runtime suspend")

Fixes: 9a2eba33 ("drm/nouveau: Fix drm poll_helper handling")
Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Cc: stable@vger.kernel.org
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

Pull timer update from Thomas Gleixner:
 "New defines for the compat time* types so they can be shared between
  32bit and 64bit builds. Not used yet, but merging them now allows the
  actual conversions to be merged through different maintainer trees
  without dependencies

  We still have compat interfaces for 32bit on 64bit even with the new
  2038 safe timespec/val variants because pointer size is different. And
  for the old style timespec/val interfaces we need yet another 'compat'
  interface for both 32bit native and 32bit on 64bit"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  y2038: Provide aliases for compat helpers

Pull IDA updates from Matthew Wilcox:
 "A better IDA API:

      id = ida_alloc(ida, GFP_xxx);
      ida_free(ida, id);

  rather than the cumbersome ida_simple_get(), ida_simple_remove().

  The new IDA API is similar to ida_simple_get() but better named.  The
  internal restructuring of the IDA code removes the bitmap
  preallocation nonsense.

  I hope the net -200 lines of code is convincing"

* 'ida-4.19' of git://git.infradead.org/users/willy/linux-dax: (29 commits)
  ida: Change ida_get_new_above to return the id
  ida: Remove old API
  test_ida: check_ida_destroy and check_ida_alloc
  test_ida: Convert check_ida_conv to new API
  test_ida: Move ida_check_max
  test_ida: Move ida_check_leaf
  idr-test: Convert ida_check_nomem to new API
  ida: Start new test_ida module
  target/iscsi: Allocate session IDs from an IDA
  iscsi target: fix session creation failure handling
  drm/vmwgfx: Convert to new IDA API
  dmaengine: Convert to new IDA API
  ppc: Convert vas ID allocation to new IDA API
  media: Convert entity ID allocation to new IDA API
  ppc: Convert mmu context allocation to new IDA API
  Convert net_namespace to new IDA API
  cb710: Convert to new IDA API
  rsxx: Convert to new IDA API
  osd: Convert to new IDA API
  sd: Convert to new IDA API
  ...

Pull gcc plugin fix from Kees Cook:
 "Lift gcc test into Kconfig. This is for better behavior when the
  kernel is built with Clang, reported by Stefan Agner"

* tag 'gcc-plugins-v4.19-rc1-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  gcc-plugins: Disable when building under Clang

Pull perf updates from Thomas Gleixner:
 "Kernel:
   - Improve kallsyms coverage
   - Add x86 entry trampolines to kcore
   - Fix ARM SPE handling
   - Correct PPC event post processing

  Tools:
   - Make the build system more robust
   - Small fixes and enhancements all over the place
   - Update kernel ABI header copies
   - Preparatory work for converting libtraceevnt to a shared library
   - License cleanups"

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (100 commits)
  tools arch: Update arch/x86/lib/memcpy_64.S copy used in 'perf bench mem memcpy'
  tools arch x86: Update tools's copy of cpufeatures.h
  perf python: Fix pyrf_evlist__read_on_cpu() interface
  perf mmap: Store real cpu number in 'struct perf_mmap'
  perf tools: Remove ext from struct kmod_path
  perf tools: Add gzip_is_compressed function
  perf tools: Add lzma_is_compressed function
  perf tools: Add is_compressed callback to compressions array
  perf tools: Move the temp file processing into decompress_kmodule
  perf tools: Use compression id in decompress_kmodule()
  perf tools: Store compression id into struct dso
  perf tools: Add compression id into 'struct kmod_path'
  perf tools: Make is_supported_compression() static
  perf tools: Make decompress_to_file() function static
  perf tools: Get rid of dso__needs_decompress() call in __open_dso()
  perf tools: Get rid of dso__needs_decompress() call in symbol__disassemble()
  perf tools: Get rid of dso__needs_decompress() call in read_object_code()
  tools lib traceevent: Change to SPDX License format
  perf llvm: Allow passing options to llc in addition to clang
  perf parser: Improve error message for PMU address filters
  ...

Pull x86 fixes from Thomas Gleixner:

 - Correct the L1TF fallout on 32bit and the off by one in the 'too much
   RAM for protection' calculation.

 - Add a helpful kernel message for the 'too much RAM' case

 - Unbreak the VDSO in case that the compiler desides to use indirect
   jumps/calls and emits retpolines which cannot be resolved because the
   kernel uses its own thunks, which does not work for the VDSO. Make it
   use the builtin thunks.

 - Re-export start_thread() which was unexported when the 32/64bit
   implementation was unified. start_thread() is required by modular
   binfmt handlers.

 - Trivial cleanups

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation/l1tf: Suggest what to do on systems with too much RAM
  x86/speculation/l1tf: Fix off-by-one error when warning that system has too much RAM
  x86/kvm/vmx: Remove duplicate l1d flush definitions
  x86/speculation/l1tf: Fix overflow in l1tf_pfn_limit() on 32bit
  x86/process: Re-export start_thread()
  x86/mce: Add notifier_block forward declaration
  x86/vdso: Fix vDSO build if a retpoline is emitted

Pull irq update from Thomas Gleixner:
 "A small set of updats/fixes for the irq subsystem:

   - Allow GICv3 interrupts to be configured as wake-up sources to
     enable wakeup from suspend

   - Make the error handling of the STM32 irqchip init function work

   - A set of small cleanups and improvements"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic-v3: Allow interrupt to be configured as wake-up sources
  irqchip/tango: Set irq handler and data in one go
  dt-bindings: irqchip: renesas-irqc: Document r8a774a1 support
  irqchip/s3c24xx: Remove unneeded comparison of unsigned long to 0
  irqchip/stm32: Fix init error handling
  irqchip/bcm7038-l1: Hide cpu offline callback when building for !SMP

Pull licking update from Thomas Gleixner:
 "Mark the switch cases which fall through to the next case with the
  proper comment so the fallthrough compiler checks can be enabled"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Mark expected switch fall-throughs

Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm

Pull libnvdimm memory-failure update from Dave Jiang:
 "As it stands, memory_failure() gets thoroughly confused by dev_pagemap
  backed mappings. The recovery code has specific enabling for several
  possible page states and needs new enabling to handle poison in dax
  mappings.

  In order to support reliable reverse mapping of user space addresses:

   1/ Add new locking in the memory_failure() rmap path to prevent races
      that would typically be handled by the page lock.

   2/ Since dev_pagemap pages are hidden from the page allocator and the
      "compound page" accounting machinery, add a mechanism to determine
      the size of the mapping that encompasses a given poisoned pfn.

   3/ Given pmem errors can be repaired, change the speculatively
      accessed poison protection, mce_unmap_kpfn(), to be reversible and
      otherwise allow ongoing access from the kernel.

  A side effect of this enabling is that MADV_HWPOISON becomes usable
  for dax mappings, however the primary motivation is to allow the
  system to survive userspace consumption of hardware-poison via dax.
  Specifically the current behavior is:

     mce: Uncorrected hardware memory error in user-access at af34214200
     {1}[Hardware Error]: It has been corrected by h/w and requires no further action
     mce: [Hardware Error]: Machine check events logged
     {1}[Hardware Error]: event severity: corrected
     Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users
     [..]
     Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed
     mce: Memory error not recovered
     <reboot>

  ...and with these changes:

     Injecting memory failure for pfn 0x20cb00 at process virtual address 0x7f763dd00000
     Memory failure: 0x20cb00: Killing dax-pmd:5421 due to hardware memory corruption
     Memory failure: 0x20cb00: recovery action for dax page: Recovered

  Given all the cross dependencies I propose taking this through
  nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax
  folks"

* tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm, pmem: Restore page attributes when clearing errors
  x86/memory_failure: Introduce {set, clear}_mce_nospec()
  x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses
  mm, memory_failure: Teach memory_failure() about dev_pagemap pages
  filesystem-dax: Introduce dax_lock_mapping_entry()
  mm, memory_failure: Collect mapping size in collect_procs()
  mm, madvise_inject_error: Let memory_failure() optionally take a page reference
  mm, dev_pagemap: Do not clear ->mapping on final put
  mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages
  filesystem-dax: Set page->index
  device-dax: Set page->index
  device-dax: Enable page_mapping()
  device-dax: Convert to vmf_insert_mixed and vm_fault_t

Pull libnvdimm updates from Dave Jiang:
 "Collection of misc libnvdimm patches for 4.19 submission:

   - Adding support to read locked nvdimm capacity.

   - Change test code to make DSM failure code injection an override.

   - Add support for calculate maximum contiguous area for namespace.

   - Add support for queueing a short ARS when there is on going ARS for
     nvdimm.

   - Allow NULL to be passed in to ->direct_access() for kaddr and pfn
     params.

   - Improve smart injection support for nvdimm emulation testing.

   - Fix test code that supports for emulating controller temperature.

   - Fix hang on error before devm_memremap_pages()

   - Fix a bug that causes user memory corruption when data returned to
     user for ars_status.

   - Maintainer updates for Ross Zwisler emails and adding Jan Kara to
     fsdax"

* tag 'libnvdimm-for-4.19_misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm:
  libnvdimm: fix ars_status output length calculation
  device-dax: avoid hang on error before devm_memremap_pages()
  tools/testing/nvdimm: improve emulation of smart injection
  filesystem-dax: Do not request kaddr and pfn when not required
  md/dm-writecache: Don't request pointer dummy_addr when not required
  dax/super: Do not request a pointer kaddr when not required
  tools/testing/nvdimm: kaddr and pfn can be NULL to ->direct_access()
  s390, dcssblk: kaddr and pfn can be NULL to ->direct_access()
  libnvdimm, pmem: kaddr and pfn can be NULL to ->direct_access()
  acpi/nfit: queue issuing of ars when an uc error notification comes in
  libnvdimm: Export max available extent
  libnvdimm: Use max contiguous area for namespace size
  MAINTAINERS: Add Jan Kara for filesystem DAX
  MAINTAINERS: update Ross Zwisler's email address
  tools/testing/nvdimm: Fix support for emulating controller temperature
  tools/testing/nvdimm: Make DSM failure code injection an override
  acpi, nfit: Prefer _DSM over _LSR for namespace label reads
  libnvdimm: Introduce locked DIMM capacity support

Pull ARM SoC late updates from Olof Johansson:
 "A couple of late-merged changes that would be useful to get in this
  merge window:

   - Driver support for reset of audio complex on Meson platforms. The
     audio driver went in this merge window, and these changes have been
     in -next for a while (just not in our tree).

   - Power management fixes for IOMMU on Rockchip platforms, getting
     closer to kexec working on them, including Chromebooks.

   - Another pass updating "arm,psci" -> "psci" for some properties that
     have snuck in since last time it was done"

* tag 'armsoc-late' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  iommu/rockchip: Move irq request past pm_runtime_enable
  iommu/rockchip: Handle errors returned from PM framework
  arm64: rockchip: Force CONFIG_PM on Rockchip systems
  ARM: rockchip: Force CONFIG_PM on Rockchip systems
  arm64: dts: Fix various entry-method properties to reflect documentation
  reset: imx7: Fix always writing bits as 0
  reset: meson: add meson audio arb driver
  reset: meson: add dt-bindings for meson-axg audio arb

Pull more Kbuild updates from Masahiro Yamada:

 - add build_{menu,n,g,x}config targets for compile-testing Kconfig

 - fix and improve recursive dependency detection in Kconfig

 - fix parallel building of menuconfig/nconfig

 - fix syntax error in clang-version.sh

 - suppress distracting log from syncconfig

 - remove obsolete "rpm" target

 - remove VMLINUX_SYMBOL(_STR) macro entirely

 - fix microblaze build with CONFIG_DYNAMIC_FTRACE

 - move compiler test for dead code/data elimination to Kconfig

 - rename well-known LDFLAGS variable to KBUILD_LDFLAGS

 - misc fixes and cleanups

* tag 'kbuild-v4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: rename LDFLAGS to KBUILD_LDFLAGS
  kbuild: pass LDFLAGS to recordmcount.pl
  kbuild: test dead code/data elimination support in Kconfig
  initramfs: move gen_initramfs_list.sh from scripts/ to usr/
  vmlinux.lds.h: remove stale <linux/export.h> include
  export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR()
  Coccinelle: remove pci_alloc_consistent semantic to detect in zalloc-simple.cocci
  kbuild: make sorting initramfs contents independent of locale
  kbuild: remove "rpm" target, which is alias of "rpm-pkg"
  kbuild: Fix LOADLIBES rename in Documentation/kbuild/makefiles.txt
  kconfig: suppress "configuration written to .config" for syncconfig
  kconfig: fix "Can't open ..." in parallel build
  kbuild: Add a space after `!` to prevent parsing as file pattern
  scripts: modpost: check memory allocation results
  kconfig: improve the recursive dependency report
  kconfig: report recursive dependency involving 'imply'
  kconfig: error out when seeing recursive dependency
  kconfig: add build-only configurator targets
  scripts/dtc: consolidate include path options in Makefile

Pull block fixes from Jens Axboe:
 "A few small fixes for this merge window:

   - Locking imbalance fix for bcache (Shan Hai)

   - A few small fixes for wbt. One is a cleanup/prep, one is a fix for
     an existing issue, and the last two are fixes for changes that went
     into this merge window (me)"

* tag 'for-linus-20180825' of git://git.kernel.dk/linux-block:
  blk-wbt: don't maintain inflight counts if disabled
  blk-wbt: fix has-sleeper queueing check
  blk-wbt: use wq_has_sleeper() for wq active check
  blk-wbt: move disable check into get_limit()
  bcache: release dc->writeback_lock properly in bch_writeback_thread()

Pull UBIFS fix from Richard Weinberger:
 "Remove an empty file from UBIFS source"

* tag 'upstream-4.19-rc1-fix' of git://git.infradead.org/linux-ubifs:
  ubifs: Remove empty file.h

Pull cifs fixes from Steve French:
 "Three small SMB3 fixes, one for stable"

* tag '4.19-rc-smb3' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: update internal module version number for cifs.ko to 2.12
  cifs: check kmalloc before use
  cifs: check if SMB2 PDU size has been padded and suppress the warning
  cifs: create a define for how many iovs we need for an SMB2_open()

This is not normally noticeable, but repeated forks are unnecessarily
expensive because they repeatedly dirty the parent page tables during
the page table copy operation.

It's trivial to just avoid write protecting the page table entry if it
was already not writable.

This patch was inspired by

    https://bugzilla.kernel.org/show_bug.cgi?id=200447

which points to an ancient "waste time re-doing fork" issue in the
presence of lots of signals.

That bug was fixed by Eric Biederman's signal handling series
culminating in commit c3ad2c3b ("signal: Don't restart fork when
signals come in"), but the unnecessary work for repeated forks is still
work just fixing, particularly since the fix is trivial.

Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

At the point where r is being checked for different values, r is always
going to be equal to 2 as the previous if statements jump to end or end1
if r is not 2.  Hence the assignment to err can be simplified to just
err an assignment without any checks on the value or r.

Detected by CoverityScan, CID#1226737 ("Logically dead code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Tejun Heo wrote:
>
> I asked Jens whether he could take care of the libata tree and he
> thankfully agreed, so, from now on, Jens will be the libata
> maintainer.
>
> Thanks a lot!

Thanks for your work in this area. I still remember the first linux
storage summit we did in Vancouver 2001, Tejun was invited to talk about
his libata error handling work. Before that, it was basically a crap
shoot if we recovered properly or not... A lot of water has flown under
the bridge since then!

Here's an "official" patch. Linus, can you apply it?
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull libata updates from Tejun Heo:
 "Nothing too interesting. Mostly ahci and ahci_platform changes, many
  around power management"

* 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata: (22 commits)
  ata: ahci_platform: enable to get and control reset
  ata: libahci_platform: add reset control support
  ata: add an extra argument to ahci_platform_get_resources()
  ata: sata_rcar: Add r8a77965 support
  ata: sata_rcar: exclude setting of PHY registers in Gen3
  ata: sata_rcar: really mask all interrupts on Gen2 and later
  Revert "ata: ahci_platform: allow disabling of hotplug to save power"
  ata: libahci: Allow reconfigure of DEVSLP register
  ata: libahci: Correct setting of DEVSLP register
  ata: ahci: Enable DEVSLP by default on x86 with SLP_S0
  ata: ahci: Support state with min power but Partial low power state
  Revert "ata: ahci_platform: convert kcalloc to devm_kcalloc"
  ata: sata_rcar: Add rudimentary Runtime PM support
  ata: sata_rcar: Provide a short-hand for &pdev->dev
  ata: Only output sg element mapped number in verbose debug
  ata: Guard ata_scsi_dump_cdb() by ATA_VERBOSE_DEBUG
  ata: ahci_platform: convert kcalloc to devm_kcalloc
  ata: ahci_platform: convert kzallloc to kcalloc
  ata: ahci_platform: correct parameter documentation for ahci_platform_shutdown
  libata: remove ata_sff_data_xfer_noirq()
  ...

Pull cgroup updates from Tejun Heo:
 "Just one commit from Steven to take out spin lock from trace event
  handlers"

* 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/tracing: Move taking of spin lock out of trace event handlers

Pull workqueue updates from Tejun Heo:
 "Over the lockdep cross-release churn, workqueue lost some of the
  existing annotations. Johannes Berg restored it and also improved
  them"

* 'for-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: re-add lockdep dependencies for flushing
  workqueue: skip lockdep wq dependency in cancel_work_sync()

Pull IOMMU updates from Joerg Roedel:

 - PASID table handling updates for the Intel VT-d driver. It implements
   a global PASID space now so that applications usings multiple devices
   will just have one PASID.

 - A new config option to make iommu passthroug mode the default.

 - New sysfs attribute for iommu groups to export the type of the
   default domain.

 - A debugfs interface (for debug only) usable by IOMMU drivers to
   export internals to user-space.

 - R-Car Gen3 SoCs support for the ipmmu-vmsa driver

 - The ARM-SMMU now aborts transactions from unknown devices and devices
   not attached to any domain.

 - Various cleanups and smaller fixes all over the place.

* tag 'iommu-updates-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (42 commits)
  iommu/omap: Fix cache flushes on L2 table entries
  iommu: Remove the ->map_sg indirection
  iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel
  iommu/arm-smmu-v3: Prevent any devices access to memory without registration
  iommu/ipmmu-vmsa: Don't register as BUS IOMMU if machine doesn't have IPMMU-VMSA
  iommu/ipmmu-vmsa: Clarify supported platforms
  iommu/ipmmu-vmsa: Fix allocation in atomic context
  iommu: Add config option to set passthrough as default
  iommu: Add sysfs attribyte for domain type
  iommu/arm-smmu-v3: sync the OVACKFLG to PRIQ consumer register
  iommu/arm-smmu: Error out only if not enough context interrupts
  iommu/io-pgtable-arm-v7s: Abort allocation when table address overflows the PTE
  iommu/io-pgtable-arm: Fix pgtable allocation in selftest
  iommu/vt-d: Remove the obsolete per iommu pasid tables
  iommu/vt-d: Apply per pci device pasid table in SVA
  iommu/vt-d: Allocate and free pasid table
  iommu/vt-d: Per PCI device pasid table interfaces
  iommu/vt-d: Add for_each_device_domain() helper
  iommu/vt-d: Move device_domain_info to header
  iommu/vt-d: Apply global PASID in SVA
  ...

Pull thermal management updates from Zhang Rui:

 - Add Daniel Lezcano as the reviewer of thermal framework and SoC
   driver changes (Daniel Lezcano).

 - Fix a bug in intel_dts_soc_thermal driver, which does not translate
   IO-APIC GSI (Global System Interrupt) into Linux irq number (Hans de
   Goede).

 - For device tree bindings, allow cooling devices sharing same trip
   point with same contribution value to share cooling map (Viresh
   Kumar).

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux:
  dt-bindings: thermal: Allow multiple devices to share cooling map
  MAINTAINERS: Add Daniel Lezcano as designated reviewer for thermal
  Thermal: Intel SoC DTS: Translate IO-APIC GSI number to linux irq number

Merge tag 'apparmor-pr-2018-08-23' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor

Pull apparmor updates from John Johansen:
 "There is nothing major this time just four bug fixes and a patch to
  remove some dead code:

  Cleanups:
   - remove no-op permission check in policy_unpack

  Bug fixes:
   - fix an error code in __aa_create_ns()
   - fix failure to audit context info in build_change_hat
   - check buffer bounds when mapping permissions mask
   - fully initialize aa_perms struct when answering userspace query"

* tag 'apparmor-pr-2018-08-23' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
  apparmor: remove no-op permission check in policy_unpack
  apparmor: fix an error code in __aa_create_ns()
  apparmor: Fix failure to audit context info in build_change_hat
  apparmor: Fully initialize aa_perms struct when answering userspace query
  apparmor: Check buffer bounds when mapping permissions mask

Pull powerpc fixes from Michael Ellerman:

 - An implementation for the newly added hv_ops->flush() for the OPAL
   hvc console driver backends, I forgot to apply this after merging the
   hvc driver changes before the merge window.

 - Enable all PCI bridges at boot on powernv, to avoid races when
   multiple children of a bridge try to enable it simultaneously. This
   is a workaround until the PCI core can be enhanced to fix the races.

 - A fix to query PowerVM for the correct system topology at boot before
   initialising sched domains, seen in some configurations to cause
   broken scheduling etc.

 - A fix for pte_access_permitted() on "nohash" platforms.

 - Two commits to fix SIGBUS when using remap_pfn_range() seen on Power9
   due to a workaround when using the nest MMU (GPUs, accelerators).

 - Another fix to the VFIO code used by KVM, the previous fix had some
   bugs which caused guests to not start in some configurations.

 - A handful of other minor fixes.

Thanks to: Aneesh Kumar K.V, Benjamin Herrenschmidt, Christophe Leroy,
Hari Bathini, Luke Dashjr, Mahesh Salgaonkar, Nicholas Piggin, Paul
Mackerras, Srikar Dronamraju.

* tag 'powerpc-4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/mce: Fix SLB rebolting during MCE recovery path.
  KVM: PPC: Book3S: Fix guest DMA when guest partially backed by THP pages
  powerpc/mm/radix: Only need the Nest MMU workaround for R -> RW transition
  powerpc/mm/books3s: Add new pte bit to mark pte temporarily invalid.
  powerpc/nohash: fix pte_access_permitted()
  powerpc/topology: Get topology for shared processors at boot
  powerpc64/ftrace: Include ftrace.h needed for enable/disable calls
  powerpc/powernv/pci: Work around races in PCI bridge enabling
  powerpc/fadump: cleanup crash memory ranges support
  powerpc/powernv: provide a console flush operation for opal hvc driver
  powerpc/traps: Avoid rate limit messages from show unhandled signals
  powerpc/64s: Fix PACA_IRQ_HARD_DIS accounting in idle_power4()

Pull s390 updates from Martin Schwidefsky:

 - A couple of patches for the zcrypt driver:
     + Add two masks to determine which AP cards and queues are host
       devices, this will be useful for KVM AP device passthrough
     + Add-on patch to improve the parsing of the new apmask and aqmask
     + Some code beautification

 - Second try to reenable the GCC plugins, the first patch set had a
   patch to do this but the merge somehow missed this

 - Remove the s390 specific GCC version check and use the generic one

 - Three patches for kdump, two bug fixes and one cleanup

 - Three patches for the PCI layer, one bug fix and two cleanups

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: remove gcc version check (4.3 or newer)
  s390/zcrypt: hex string mask improvements for apmask and aqmask.
  s390/zcrypt: AP bus support for alternate driver(s)
  s390/zcrypt: code beautify
  s390/zcrypt: switch return type to bool for ap_instructions_available()
  s390/kdump: Remove kzalloc_panic
  s390/kdump: Fix memleak in nt_vmcoreinfo
  s390/kdump: Make elfcorehdr size calculation ABI compliant
  s390/pci: remove fmb address from debug output
  s390/pci: remove stale rc
  s390/pci: fix out of bounds access during irq setup
  s390/zcrypt: fix ap_instructions_available() returncodes
  s390: reenable gcc plugins for real

Pull ACPI Kconfig fix from Rafael Wysocki:
 "Fix recent menuconfig breakage causing it to present ACPI-specific
  options incorrectly (Arnd Bergmann)"

* tag 'acpi-4.19-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: fix menuconfig presentation of ACPI submenu

Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull namespace fixes from Eric Biederman:
 "This is a set of four fairly obvious bug fixes:

   - a switch from d_find_alias to d_find_any_alias because the xattr
     code perversely takes a dentry

   - two mutex vs copy_to_user fixes from Jann Horn

   - a fix to use a sanitized size not the size userspace passed in from
     Christian Brauner"

* 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  getxattr: use correct xattr length
  sys: don't hold uts_sem while accessing userspace memory
  userns: move user access out of the mutex
  cap_inode_getsecurity: use d_find_any_alias() instead of d_find_alias()

Pull drm fixes from Dave Airlie:
 "Just a couple of fixes"

  One MAINTAINERS address change, two panels fixes, and set of amdgpu
  fixes (build fixes, display fixes and some others)"

* tag 'drm-next-2018-08-24' of git://anongit.freedesktop.org/drm/drm:
  drm/edid: Add 6 bpc quirk for SDC panel in Lenovo B50-80
  drm/amd/display: Don't build DCN1 when kcov is enabled
  Revert "drm/amdgpu/display: Replace CONFIG_DRM_AMD_DC_DCN1_0 with CONFIG_X86"
  drm/amdgpu/display: disable eDP fast boot optimization on DCE8
  drm/amdgpu: fix amdgpu_amdkfd_remove_eviction_fence v3
  drm/amdgpu: fix incorrect use of drm_file->pid
  drm/amdgpu: fix incorrect use of fcheck
  drm/powerplay: enable dpm under pass-through
  drm/amdgpu: access register without KIQ
  drm/amdgpu: set correct base for THM/NBIF/MP1 IP
  drm/amd/display: fix dentist did ranges
  drm/amd/display: make dp_ss_off optional
  drm/amd/display: fix dp_ss_control vbios flag parsing
  drm/amd/display: Do not retain link settings
  MAINTAINERS: drm-misc: Change seanpaul's email address
  drm/panel: simple: tv123wam: Add unprepare delay