On Tue, Jul 12, 2016 at 06:49:34PM +0200, Peter Wu wrote:
> The FBIOPUT_CON2FBMAP ioctl takes a console_lock(). When this is called
> while nouveau was runtime suspended, a deadlock would occur due to
> nouveau_fbcon_set_suspend also trying to obtain console_lock().
>
> Fix this by delaying the drm_fb_helper_set_suspend call. Based on the
> i915 code (which was done for performance reasons though).
>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Signed-off-by: Peter Wu <peter at lekensteyn.nl>
> ---
> Tested on top of v4.7-rc5, the deadlock is gone.
> ---
> drivers/gpu/drm/nouveau/nouveau_drm.c | 4 +--
> drivers/gpu/drm/nouveau/nouveau_drv.h | 1 +
> drivers/gpu/drm/nouveau/nouveau_fbcon.c | 54
> ++++++++++++++++++++++++++++-----
> drivers/gpu/drm/nouveau/nouveau_fbcon.h | 2 +-
> 4 files changed, 50 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c
> b/drivers/gpu/drm/nouveau/nouveau_drm.c
> index 11f8dd9..f9a2c10 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -552,7 +552,7 @@ nouveau_do_suspend(struct drm_device *dev, bool runtime)
>
> if (dev->mode_config.num_crtc) {
> NV_INFO(drm, "suspending console...\n");
> - nouveau_fbcon_set_suspend(dev, 1);
> + nouveau_fbcon_set_suspend(dev, FBINFO_STATE_SUSPENDED, true);
> NV_INFO(drm, "suspending display...\n");
> ret = nouveau_display_suspend(dev, runtime);
> if (ret)
> @@ -635,7 +635,7 @@ nouveau_do_resume(struct drm_device *dev, bool runtime)
> NV_INFO(drm, "resuming display...\n");
> nouveau_display_resume(dev, runtime);
> NV_INFO(drm, "resuming console...\n");
> - nouveau_fbcon_set_suspend(dev, 0);
> + nouveau_fbcon_set_suspend(dev, FBINFO_STATE_RUNNING, false);
> }
>
> return 0;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_drv.h
> b/drivers/gpu/drm/nouveau/nouveau_drv.h
> index 822a021..a743d19 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_drv.h
> +++ b/drivers/gpu/drm/nouveau/nouveau_drv.h
> @@ -147,6 +147,7 @@ struct nouveau_drm {
> struct nouveau_channel *channel;
> struct nvkm_gpuobj *notify;
> struct nouveau_fbdev *fbcon;
> + struct work_struct fbdev_suspend_work;
> struct nvif_object nvsw;
> struct nvif_object ntfy;
> struct nvif_notify flip;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
> b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
> index d1f248f..089156a 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_fbcon.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_fbcon.c
> @@ -492,19 +492,53 @@ static const struct drm_fb_helper_funcs
> nouveau_fbcon_helper_funcs = {
> .fb_probe = nouveau_fbcon_create,
> };
>
> +static void nouveau_fbcon_suspend_worker(struct work_struct *work)
> +{
> + nouveau_fbcon_set_suspend(container_of(work,
> + struct nouveau_drm,
> + fbdev_suspend_work)->dev,
> + FBINFO_STATE_RUNNING,
> + true);
> +}
> +
> void
> -nouveau_fbcon_set_suspend(struct drm_device *dev, int state)
> +nouveau_fbcon_set_suspend(struct drm_device *dev, int state, bool
> synchronous)
> {
> struct nouveau_drm *drm = nouveau_drm(dev);
> - if (drm->fbcon) {
> - console_lock();
> - if (state == FBINFO_STATE_RUNNING)
> - nouveau_fbcon_accel_restore(dev);
> - drm_fb_helper_set_suspend(&drm->fbcon->helper, state);
> + if (!drm->fbcon)
> + return;
> +
> + if (synchronous) {
> + /* Flush any pending work to turn the console on, and then
> + * wait to turn it off. It must be synchronous as we are
> + * about to suspend or unload the driver.
> + *
> + * Note that from within the work-handler, we cannot flush
> + * ourselves, so only flush outstanding work upon suspend!
> + */
> if (state != FBINFO_STATE_RUNNING)
> - nouveau_fbcon_accel_save_disable(dev);
> - console_unlock();
> + flush_work(&drm->fbdev_suspend_work);
> + console_lock();
> + } else {
> + /*
> + * The console lock can be pretty contented on resume due
> + * to all the printk activity. Try to keep it out of the hot
> + * path of resume if possible. This also prevents a deadlock
> + * with FBIOPUT_CON2FBMAP.
> + */
> + WARN_ON(state != FBINFO_STATE_RUNNING);
> + if (!console_trylock()) {
> + schedule_work(&drm->fbdev_suspend_work);
> + return;
> + }
> }
> +
> + if (state == FBINFO_STATE_RUNNING)
> + nouveau_fbcon_accel_restore(dev);
> + drm_fb_helper_set_suspend(&drm->fbcon->helper, state);
> + if (state != FBINFO_STATE_RUNNING)
> + nouveau_fbcon_accel_save_disable(dev);
> + console_unlock();
> }
>
> int
> @@ -526,6 +560,8 @@ nouveau_fbcon_init(struct drm_device *dev)
> fbcon->dev = dev;
> drm->fbcon = fbcon;
>
> + INIT_WORK(&drm->fbdev_suspend_work, nouveau_fbcon_suspend_worker);
> +
> drm_fb_helper_prepare(dev, &fbcon->helper, &nouveau_fbcon_helper_funcs);
>
> ret = drm_fb_helper_init(dev, &fbcon->helper,
> @@ -571,6 +607,8 @@ nouveau_fbcon_fini(struct drm_device *dev)
> if (!drm->fbcon)
> return;
>
> + flush_work(&drm->fbdev_suspend_work);
Hmm, since suspend_work can theorectically rearm itself, this should be
cancel_work_sync().
The copy'n'paste of the code looks fine, so (other than the bug copied
across):
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
Whether you can convince the maintainers on the basis of this being a
deadlock fix is another matter...
I did test this patch, since I see a livelock on resume, but not the
same console deadlock. Just in case anyone is interested:
Jul 13 17:05:59 acer kernel: [24873.945839] NMI watchdog: BUG: soft lockup -
CPU#2 stuck for 22s! [kworker/2:1:8370]
Jul 13 17:05:59 acer kernel: [24873.946563] Modules linked in: rfcomm drbg
ansi_cprng ctr ccm arc4 bnep ath10k_pci ath10k_core snd_hda_codec_hdmi
snd_hda_codec_realtek ath snd_hda_co
dec_generic snd_hda_intel mac80211 snd_hda_codec binfmt_misc snd_hda_core
nls_iso8859_1 snd_hwdep btusb btrtl snd_pcm btbcm rtsx_usb_ms btintel
x86_pkg_temp_thermal uvcvideo acer_wmi
intel_powerclamp memstick snd_seq_midi bluetooth sparse_keymap
snd_seq_midi_event coretemp videobuf2_vmalloc videobuf2_memops snd_rawmidi
kvm_intel videobuf2_v4l2 kvm cfg80211 video
buf2_core snd_seq videodev irqbypass snd_seq_device snd_timer media
crct10dif_pclmul snd crc32_pclmul hid_multitouch ghash_clmulni_intel
aesni_intel joydev aes_x86_64 lrw gf128mul gl
ue_helper ablk_helper cryptd soundcore ie31200_edac edac_core mei_me shpchp mei
input_leds acpi_als serio_raw kfifo_buf lpc_ich industrialio soc_button_array
mac_hid parport_pc ppdev
lp parport autofs4 btrfs xor raid6_pq dm_mirror dm_region_hash dm_log nouveau
rtsx_usb_sdmmc rtsx_usb hid_generic usbhid hid i915 broadcom bcm_phy_lib
mxm_wmi ttm i2c_algo_bit drm_k
ms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops drm tg3 ahci ptp
libahci pps_core video wmi fjes
Jul 13 17:05:59 acer kernel: [24873.946598] CPU: 2 PID: 8370 Comm: kworker/2:1
Tainted: G L 4.7.0-rc6+ #4
Jul 13 17:05:59 acer kernel: [24873.946599] Hardware name: Acer Aspire
VN7-791G/Aspire VN7-791G, BIOS V1.11 01/09/2015
Jul 13 17:05:59 acer kernel: [24873.946603] Workqueue: pm pm_runtime_work
Jul 13 17:05:59 acer kernel: [24873.946604] task: ffff880023c59c80 ti:
ffff880024058000 task.ti: ffff880024058000
Jul 13 17:05:59 acer kernel: [24873.946605] RIP: 0010:[<ffffffff8140a6c0>]
[<ffffffff8140a6c0>] ioread32+0x30/0x40
Jul 13 17:05:59 acer kernel: [24873.946608] RSP: 0018:ffff88002405baf0 EFLAGS:
00000296
Jul 13 17:05:59 acer kernel: [24873.946609] RAX: 00000000ffffffff RBX:
ffff88041734a000 RCX: 0000000000000018
Jul 13 17:05:59 acer kernel: [24873.946610] RDX: 0012230aadf99e58 RSI:
ffffc9000410a014 RDI: ffffc90004009410
Jul 13 17:05:59 acer kernel: [24873.946610] RBP: ffff88002405bb10 R08:
0000000000000009 R09: ffff880416ce0000
Jul 13 17:05:59 acer kernel: [24873.946611] R10: 000000000000000a R11:
0000000000000001 R12: 00000000ffffffff
Jul 13 17:05:59 acer kernel: [24873.946612] R13: 00000000ffffffff R14:
ffff880415de6600 R15: ffffffffffffffff
Jul 13 17:05:59 acer kernel: [24873.946613] FS: 0000000000000000(0000)
GS:ffff88045f280000(0000) knlGS:0000000000000000
Jul 13 17:05:59 acer kernel: [24873.946614] CS: 0010 DS: 0000 ES: 0000 CR0:
0000000080050033
Jul 13 17:05:59 acer kernel: [24873.946614] CR2: 00007f566a5ac010 CR3:
0000000002e06000 CR4: 00000000001406e0
Jul 13 17:05:59 acer kernel: [24873.946615] Stack:
Jul 13 17:05:59 acer kernel: [24873.946616] ffffffffc03bee71 ffff88041734a000
0000000000000000 ffff880415de7908
Jul 13 17:05:59 acer kernel: [24873.946617] ffff88002405bb20 ffffffffc03be9bf
ffff88002405bb58 ffffffffc03b7340
Jul 13 17:05:59 acer kernel: [24873.946618] ffff880415de7908 ffff88041734a000
00000414ef5b0e40 0000000000000011
Jul 13 17:05:59 acer kernel: [24873.946620] Call Trace:
Jul 13 17:05:59 acer kernel: [24873.946645] [<ffffffffc03bee71>] ?
nv04_timer_read+0x51/0x70 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946661] [<ffffffffc03be9bf>]
nvkm_timer_read+0xf/0x20 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946676] [<ffffffffc03b7340>]
nvkm_pmu_init+0x50/0x450 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946685] [<ffffffffc0371ac1>]
nvkm_subdev_init+0x91/0x200 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946701] [<ffffffffc03c2f26>]
nvkm_device_init+0x146/0x280 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946715] [<ffffffffc03c6a18>]
nvkm_udevice_init+0x48/0x60 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946724] [<ffffffffc0370440>]
nvkm_object_init+0x40/0x190 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946733] [<ffffffffc03704b4>]
nvkm_object_init+0xb4/0x190 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946742] [<ffffffffc036d56e>]
nvkm_client_init+0xe/0x10 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946758] [<ffffffffc040ac0e>]
nvkm_client_resume+0xe/0x10 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946767] [<ffffffffc036c7c7>]
nvif_client_resume+0x17/0x20 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946782] [<ffffffffc04082fb>]
nouveau_do_resume+0x4b/0x130 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946797] [<ffffffffc0408709>]
nouveau_pmops_runtime_resume+0x79/0x120 [nouveau]
Jul 13 17:05:59 acer kernel: [24873.946800] [<ffffffff814448eb>]
pci_pm_runtime_resume+0x7b/0xa0
Jul 13 17:05:59 acer kernel: [24873.946801] [<ffffffff815676d3>]
__rpm_callback+0x33/0x70
Jul 13 17:05:59 acer kernel: [24873.946803] [<ffffffff81444870>] ?
pci_restore_standard_config+0x40/0x40
Jul 13 17:05:59 acer kernel: [24873.946804] [<ffffffff81567734>]
rpm_callback+0x24/0x80
Jul 13 17:05:59 acer kernel: [24873.946806] [<ffffffff81444870>] ?
pci_restore_standard_config+0x40/0x40
Jul 13 17:05:59 acer kernel: [24873.946807] [<ffffffff81567ee1>]
rpm_resume+0x491/0x690
Jul 13 17:05:59 acer kernel: [24873.946808] [<ffffffff81568f08>]
pm_runtime_work+0x58/0xa0
Jul 13 17:05:59 acer kernel: [24873.946811] [<ffffffff8109adbb>]
process_one_work+0x16b/0x480
Jul 13 17:05:59 acer kernel: [24873.946812] [<ffffffff8109b11b>]
worker_thread+0x4b/0x500
Jul 13 17:05:59 acer kernel: [24873.946814] [<ffffffff8109b0d0>] ?
process_one_work+0x480/0x480
Jul 13 17:05:59 acer kernel: [24873.946815] [<ffffffff8109b0d0>] ?
process_one_work+0x480/0x480
Jul 13 17:05:59 acer kernel: [24873.946816] [<ffffffff810a1348>]
kthread+0xd8/0xf0
Jul 13 17:05:59 acer kernel: [24873.946818] [<ffffffff81845fdf>]
ret_from_fork+0x1f/0x40
Jul 13 17:05:59 acer kernel: [24873.946819] [<ffffffff810a1270>] ?
kthread_create_on_node+0x1a0/0x1a0
Jul 13 17:05:59 acer kernel: [24873.946820] Code: 03 00 77 25 48 81 ff 00 00 01
00 76 05 0f b7 d7 ed c3 55 48 c7 c6 e4 36 cc 81 48 89 e5 e8 19 ff ff ff b8 ff
ff ff ff 5d c3 8b 07 <c3
> 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 81 fe ff ff
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
