On 17/07/17 15:48, Piotr Gregor wrote:
Calling blocking operations from wrong context.
Kernel:
Linux piotrpc 4.4.70-rt83 #1 SMP PREEMPT RT Thu Jul 13 08:42:02 BST 2017 x86_64
GNU/Linux
[ 80.542018] NOHZ: local_softirq_pending 80
[ 125.175471] ------------[ cut here ]------------
[ 125.175491] WARNING: CPU: 0 PID: 1497 at kernel/sched/core.c:7833
__might_sleep+0x9f/0xb0()
[ 125.175728] do not call blocking ops when !TASK_RUNNING; state=1 set at
[<ffffffffc0575741>] comedi_read+0x1a1/0x610 [comedi]
[ 125.175735] Modules linked in: cpufreq_conservative cpufreq_powersave
cpufreq_userspace cfg80211 nfsd auth_rpcgss oid_registry nfs_acl nfs lockd
grace fscache sunrpc nls_ascii nls_cp437 vfat fat snd_hda_codec_hdmi
snd_hda_codec_realtek snd_hda_codec_generic intel_rapl joydev intel_powerclamp
coretemp kvm drbg efi_pstore ansi_cprng irqbypass crct10dif_pclmul crc32_pclmul
ghash_clmulni_intel aesni_intel aes_x86_64 lrw gf128mul glue_helper ablk_helper
cryptd i915 serio_raw pcspkr efivars snd_hda_intel amplc_dio200_pci(C)
amplc_dio200_common(C) snd_hda_codec iTCO_wdt comedi_8254(C) comedi_pci(C)
iTCO_vendor_support comedi(C) snd_hda_core snd_hwdep snd_pcm drm_kms_helper
snd_timer drm snd mei_me soundcore mei i2c_algo_bit shpchp eeepc_wmi asus_wmi
sparse_keymap mxm_wmi battery hci_uart btbcm btqca btintel
[ 125.175824] bluetooth
[ 125.175825] wmi
[ 125.175826] rfkill
[ 125.175827] video
[ 125.175828] intel_lpss_acpi
[ 125.175830] intel_lpss
[ 125.175831] evdev
[ 125.175832] mfd_core
[ 125.175833] acpi_als
[ 125.175834] acpi_pad
[ 125.175835] kfifo_buf
[ 125.175836] button
[ 125.175838] industrialio
[ 125.175839] fuse
[ 125.175840] parport_pc
[ 125.175841] ppdev
[ 125.175842] lp
[ 125.175843] parport
[ 125.175844] autofs4
[ 125.175845] ext4
[ 125.175846] crc16
[ 125.175847] mbcache
[ 125.175848] jbd2
[ 125.175849] hid_generic
[ 125.175851] usbhid
[ 125.175852] sg
[ 125.175853] sr_mod
[ 125.175854] cdrom
[ 125.175855] sd_mod
[ 125.175856] crc32c_intel
[ 125.175857] ahci
[ 125.175858] libahci
[ 125.175859] psmouse
[ 125.175860] xhci_pci
[ 125.175861] libata
[ 125.175862] r8169
[ 125.175864] i2c_i801
[ 125.175865] mii
[ 125.175866] xhci_hcd
[ 125.175867] tg3
[ 125.175868] ptp
[ 125.175869] scsi_mod
[ 125.175870] usbcore
[ 125.175871] pps_core
[ 125.175872] libphy
[ 125.175873] usb_common
[ 125.175874] fan
[ 125.175875] thermal
[ 125.175876] i2c_hid
[ 125.175877] hid
[ 125.175878] fjes
[ 125.175926] CPU: 0 PID: 1497 Comm: txrx Tainted: G WC
4.4.70-rt83 #1
[ 125.175928] Hardware name: NOVATECH LTD PC-XB04472/H110M-C, BIOS 3019
01/06/2017
[ 125.175935] 0000000000000000 ffff8802205b3cb0 ffffffff81387160
ffff8802205b3cf8
[ 125.175940] 0000000000000009 ffff8802205b3ce8 ffffffff81089766
ffffffffc057ca60
[ 125.175944] 00000000000002dc 0000000000000000 0000000000000001
0000000000000001
[ 125.175945] Call Trace:
[ 125.175955] [<ffffffff81387160>] dump_stack+0x85/0xc5
[ 125.175963] [<ffffffff81089766>] warn_slowpath_common+0x86/0xe0
[ 125.175971] [<ffffffff8108980c>] warn_slowpath_fmt+0x4c/0x50
[ 125.175980] [<ffffffff81185577>] ? trace_preempt_on+0x1a7/0x2b0
[ 125.175985] [<ffffffff8168ca95>] ? schedule+0x55/0xe0
[ 125.175994] [<ffffffffc0575741>] ? comedi_read+0x1a1/0x610 [comedi]
[ 125.176001] [<ffffffffc0575741>] ? comedi_read+0x1a1/0x610 [comedi]
[ 125.176005] [<ffffffff810b6d0f>] __might_sleep+0x9f/0xb0
[ 125.176012] [<ffffffff811f54cb>] __might_fault+0x3b/0xb0
[ 125.176020] [<ffffffffc057597f>] comedi_read+0x3df/0x610 [comedi]
[ 125.176034] [<ffffffff810bebf0>] ? wake_up_process+0x20/0x20
[ 125.176044] [<ffffffff812406d8>] __vfs_read+0x28/0xe0
[ 125.176053] [<ffffffff812f1f06>] ? security_file_permission+0xa6/0xc0
[ 125.176060] [<ffffffff81240c53>] ? rw_verify_area+0x53/0xf0
[ 125.176066] [<ffffffff81240d79>] vfs_read+0x89/0x130
[ 125.176074] [<ffffffff81241b79>] SyS_read+0x49/0xb0
[ 125.176084] [<ffffffff81691876>] entry_SYSCALL_64_fastpath+0x16/0x7a
[ 125.176095] ---[ end trace 0000000000000003 ]---
cheers,
Piotr
Thanks for the bug report. I think comedi_read() in
"drivers/staging/comedi/comedi_fops.c" needs a call to
set_current_state(TASK_RUNNING) just before the call to copy_to_user(...).
Similarly, comedi_write() needs a call to set_current_task(TASK_RUNNING)
just before the call to copy_from_user(...), and another call to
set_current_task(TASK_RUNNING) before the call to mutex_lock().
I'll work on a patch.
--
-=( Ian Abbott @ MEV Ltd. E-mail: <abbo...@mev.co.uk> )=-
-=( Web: http://www.mev.co.uk/ )=-
