I came across a strange problem in openSUSE Leap 15.0 on a Raspberry Pi 3 B+.
The system freezes when I open two /dev/ttyUSBx devices. This problem is fixed
within the current Tumbleweed Raspberry Pi 3 aarch64 release.
Kernel: 4.12.14-lp150.12.22-default
How to reproduce:
1. Connect two USB serial adapters to the system.
2. Open the first device inside a terminal.
#> cat /dev/ttyUSB0
3. Open the second device inside another terminal.
#> cat /dev/ttyUSB1
Result: System freezes.
I'm not sure if the following points to the cause of this problem, but it
happened during one of the freezes.
[ 7992.034984] NMI watchdog: BUG: soft lockup - CPU#0 stuck for 23s!
[swapper/0:0]
[ 7992.034999] Modules linked in: xt_nat xt_tcpudp veth ipt_MASQUERADE
nf_nat_masquerade_ipv4 nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo
iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 xt_addrtype
iptable_filter ip_tables xt_conntrack x_tables nf_nat nf_conntrack libcrc32c
br_netfilter bridge stp llc overlay af_packet vc4 brcmfmac snd_soc_core
ac97_bus snd_pcm_dmaengine snd_pcm snd_timer brcmutil snd cfg80211 ftdi_sio
soundcore drm_kms_helper nls_iso8859_1 rfkill fb_ili9341(C) nls_cp437 vfat fat
drm usbserial joydev smsc95xx usbnet fbtft(C) mii drm_panel_orientation_quirks
fb_sys_fops syscopyarea ads7846 sysfillrect sysimgblt raspberrypi_hwmon
spi_bcm2835 vchiq(C) bcm2835_thermal bcm2835_wdt bcm2835_rng crc32_ce
uio_pdrv_genirq uio leds_gpio mmc_block dwc2 i2c_bcm2835 sdhci_iproc
sdhci_pltfm
[ 7992.035218] usbcore sdhci bcm2835 mmc_core bcm2835_dma phy_generic fixed sg
efivarfs
[ 7992.035257] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G C
4.12.14-lp150.12.22-default #1 openSUSE Leap 15.0
[ 7992.035261] Hardware name: raspberrypi rpi/rpi, BIOS 2018.03 04/12/2018
[ 7992.035267] task: ffff000008e82a00 task.stack: ffff000008e70000
[ 7992.035466] PC is at usb_hcd_unmap_urb_for_dma+0xd0/0x148 [usbcore]
[ 7992.035642] LR is at usb_hcd_unmap_urb_for_dma+0x28/0x148 [usbcore]
[ 7992.035648] pc : [<ffff000000a047e0>] lr : [<ffff000000a04738>] pstate:
20000005
[ 7992.035651] sp : ffff80003df4bb60
[ 7992.035655] x29: ffff80003df4bb60 x28: 0000000000000040
[ 7992.035664] x27: 0000000000000007 x26: ffff000008e761b0
[ 7992.035673] x25: ffff000008e76180 x24: ffff000008e5d018
[ 7992.035682] x23: 0000000000000006 x22: 0000000000000000
[ 7992.035691] x21: ffff80002c24e800 x20: ffff80002c24e800
[ 7992.035700] x19: ffff80002c3b9600 x18: 0000000000000000
[ 7992.035709] x17: 0000000000000002 x16: 0000000000000000
[ 7992.035717] x15: 000000000000000c x14: ffff80002c0da400
[ 7992.035726] x13: ffff80002c0da900 x12: ffff80002c0daf00
[ 7992.035735] x11: 0000000000000003 x10: 0000000000000200
[ 7992.035743] x9 : 0000000000000000 x8 : ffff80003b66f200
[ 7992.035752] x7 : 0000000000000000 x6 : 000000000000003f
[ 7992.035760] x5 : 0000000000000040 x4 : 0000000000010200
[ 7992.035769] x3 : 0000000000000002 x2 : 0000000000010200
[ 7992.035777] x1 : ffff80002c3b9600 x0 : ffff000000a04738
[ 7992.035787] Call trace:
[ 7992.035795] Exception stack(0xffff80003df4ba20 to 0xffff80003df4bb60)
[ 7992.035803] ba20: ffff000000a04738 ffff80002c3b9600 0000000000010200
0000000000000002
[ 7992.035811] ba40: 0000000000010200 0000000000000040 000000000000003f
0000000000000000
[ 7992.035819] ba60: ffff80003b66f200 0000000000000000 0000000000000200
0000000000000003
[ 7992.035827] ba80: ffff80002c0daf00 ffff80002c0da900 ffff80002c0da400
000000000000000c
[ 7992.035835] baa0: 0000000000000000 0000000000000002 0000000000000000
ffff80002c3b9600
[ 7992.035842] bac0: ffff80002c24e800 ffff80002c24e800 0000000000000000
0000000000000006
[ 7992.035850] bae0: ffff000008e5d018 ffff000008e76180 ffff000008e761b0
0000000000000007
[ 7992.035858] bb00: 0000000000000040 ffff80003df4bb60 ffff000000a04738
ffff80003df4bb60
[ 7992.035866] bb20: ffff000000a047e0 0000000020000005 0000000000000000
ffff80002c24e800
[ 7992.035874] bb40: 0000ffffffffffff ffff000000a04738 ffff80003df4bb60
ffff000000a047e0
[ 7992.036052] [<ffff000000a047e0>] usb_hcd_unmap_urb_for_dma+0xd0/0x148
[usbcore]
[ 7992.036129] [<ffff000000a9b3e0>] dwc2_unmap_urb_for_dma+0x28/0x40 [dwc2]
[ 7992.036307] [<ffff000000a0488c>] unmap_urb_for_dma+0x34/0x48 [usbcore]
[ 7992.036483] [<ffff000000a04978>] __usb_hcd_giveback_urb+0x40/0x158 [usbcore]
[ 7992.036660] [<ffff000000a04b30>] usb_giveback_urb_bh+0xa0/0xe8 [usbcore]
[ 7992.036675] [<ffff0000080dc534>] tasklet_action+0x74/0x110
[ 7992.036685] [<ffff000008081a28>] __do_softirq+0x130/0x334
[ 7992.036695] [<ffff0000080dbf88>] irq_exit+0xc0/0xf0
[ 7992.036706] [<ffff00000813e59c>] __handle_domain_irq+0x6c/0xc0
[ 7992.036714] [<ffff0000080815e0>] bcm2836_arm_irqchip_handle_irq+0x78/0xd8
[ 7992.036720] Exception stack(0xffff000008e73de0 to 0xffff000008e73f20)
[ 7992.036728] 3de0: 00000001000bb233 0000000000000080 00000000000003e8
ffff0000087a67f8
[ 7992.036736] 3e00: 0000000004ea4a8c 00ffffffffffffff 00000023b0c50175
0000000000000002
[ 7992.036744] 3e20: ffff000008e84450 ffff000008e73e90 00000000000019f0
0000000000000003
[ 7992.036751] 3e40: 0000000000000003 ffff000008962fe8 0000000000000000
000000000000000c
[ 7992.036759] 3e60: 0000000000000000 000000000000000e 0000000000000000
00000000000000bd
[ 7992.036767] 3e80: 0000000000000000 ffff000008ff9000 ffff000008e79000
ffff80003dfff400
[ 7992.036775] 3ea0: ffff000008d9f028 000000003ca05000 000000003c9840c0
0000000000000000
[ 7992.036783] 3ec0: 0000000000ce0018 ffff000008e73f20 ffff00000816ec78
ffff000008e73f20
[ 7992.036791] 3ee0: ffff00000816ec7c 0000000020000005 000000003ca05000
000000003c9840c0
[ 7992.036799] 3f00: ffffffffffffffff 0000000000ce0018 ffff000008e73f20
ffff00000816ec7c
[ 7992.036807] [<ffff0000080830b0>] el1_irq+0xb0/0x140
[ 7992.036818] [<ffff00000816ec7c>] tick_nohz_idle_enter+0x3c/0x48
[ 7992.036826] [<ffff000008121e68>] do_idle+0x28/0x1f8
[ 7992.036833] [<ffff0000081221e4>] cpu_startup_entry+0x2c/0x30
[ 7992.036843] [<ffff00000892eecc>] rest_init+0x74/0x80
[ 7992.036854] [<ffff000008ce0d68>] start_kernel+0x3c0/0x3d4