Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751466AbdGQQCw (ORCPT ); Mon, 17 Jul 2017 12:02:52 -0400 Received: from smtp73.ord1c.emailsrvr.com ([108.166.43.73]:43861 "EHLO smtp73.ord1c.emailsrvr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751443AbdGQQCs (ORCPT ); Mon, 17 Jul 2017 12:02:48 -0400 X-Auth-ID: siepeng@mev.co.uk X-Sender-Id: siepeng@mev.co.uk Subject: Re: [BUG] drivers: staging: comedi: do not call blocking ops when !TASK_RUNNING; state=1 To: Piotr Gregor , linux-rt-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, sebastian.siewior@linutronix.de, tglx@linutronix.de, gregkh@linuxfoundation.org, devel@driverdev.osuosl.org References: <20170717144850.GA1696@piotrpc> From: Ian Abbott Message-ID: <710d1c24-a4f2-c0c0-3d20-76e1f0e402a9@mev.co.uk> Date: Mon, 17 Jul 2017 17:02:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170717144850.GA1696@piotrpc> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4860 Lines: 105 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 [] 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] [] dump_stack+0x85/0xc5 > [ 125.175963] [] warn_slowpath_common+0x86/0xe0 > [ 125.175971] [] warn_slowpath_fmt+0x4c/0x50 > [ 125.175980] [] ? trace_preempt_on+0x1a7/0x2b0 > [ 125.175985] [] ? schedule+0x55/0xe0 > [ 125.175994] [] ? comedi_read+0x1a1/0x610 [comedi] > [ 125.176001] [] ? comedi_read+0x1a1/0x610 [comedi] > [ 125.176005] [] __might_sleep+0x9f/0xb0 > [ 125.176012] [] __might_fault+0x3b/0xb0 > [ 125.176020] [] comedi_read+0x3df/0x610 [comedi] > [ 125.176034] [] ? wake_up_process+0x20/0x20 > [ 125.176044] [] __vfs_read+0x28/0xe0 > [ 125.176053] [] ? security_file_permission+0xa6/0xc0 > [ 125.176060] [] ? rw_verify_area+0x53/0xf0 > [ 125.176066] [] vfs_read+0x89/0x130 > [ 125.176074] [] SyS_read+0x49/0xb0 > [ 125.176084] [] 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: )=- -=( Web: http://www.mev.co.uk/ )=-