[REGRESSION] linux-next panics when trying to mount root

[Peter Rosin]

Hi!

When trying next-20180116 I get the following panic during boot:

Linux version 4.15.0-rc8-next-20180116 (peda@orc) (gcc version 4.9.2 20140811 (prerelease) (crosstool-NG linaro-1.13.1-4.9-2014.08 - Linaro GCC 4.9-2014.08)) #208 Tue Jan 16 14:23:44 CET 2018
CPU: ARMv7 Processor [410fc051] revision 1 (ARMv7), cr=10c53c7d
CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
OF: fdt: Machine model: Axentia Linea-Nattis v2 Natte v2
Memory policy: Data cache writeback
CPU: All CPU(s) started in SVC mode.
random: fast init done
Built 1 zonelists, mobility grouping on.  Total pages: 16256
Kernel command line: console=ttyS0,115200 rw consoleblank=0 ip=none root=ubi0:rootfs ubi.mtd=6 rootfstype=ubifs noinitrd mtdparts=atmel_nand:256k(at91bootstrap),384k(barebox)ro,256k@768k(bareboxenv),256k(bareboxenv2),128k@1536k(oftree),5M@2M(kernel),-@8M(rootfs)
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 56244K/65536K available (5120K kernel code, 183K rwdata, 1064K rodata, 1024K init, 108K bss, 9292K reserved, 0K cma-reserved)
Virtual kernel memory layout:
    vector  : 0xffff0000 - 0xffff1000   (   4 kB)
    fixmap  : 0xffc00000 - 0xfff00000   (3072 kB)
    vmalloc : 0xc4800000 - 0xff800000   ( 944 MB)
    lowmem  : 0xc0000000 - 0xc4000000   (  64 MB)
      .text : 0x(ptrval) - 0x(ptrval)   (6112 kB)
      .init : 0x(ptrval) - 0x(ptrval)   (1024 kB)
      .data : 0x(ptrval) - 0x(ptrval)   ( 184 kB)
       .bss : 0x(ptrval) - 0x(ptrval)   ( 109 kB)
NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
clocksource: pit: mask: 0xfffffff max_cycles: 0xfffffff, max_idle_ns: 14479245754 ns
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 21474836475000000ns
Console: colour dummy device 80x30
Calibrating delay loop... 351.43 BogoMIPS (lpj=1757184)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 1024 (order: 0, 4096 bytes)
Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes)
CPU: Testing write buffer coherency: ok
Setting up static identity map for 0x20100000 - 0x20100060
devtmpfs: initialized
VFP support v0.3: implementor 41 architecture 2 part 30 variant 5 rev 1
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 256 (order: -1, 3072 bytes)
pinctrl core: initialized pinctrl subsystem
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
AT91: PM: standby: standby, suspend: ulp0
No ATAGs?
gpio-at91 fffff200.gpio: at address 45a5b6d3
gpio-at91 fffff400.gpio: at address d0c9dba6
gpio-at91 fffff600.gpio: at address fb737fc9
gpio-at91 fffff800.gpio: at address c5aa2ee6
gpio-at91 fffffa00.gpio: at address 4663f5ca
pinctrl-at91 ahb:apb:pinctrl@fffff200: initialized AT91 pinctrl driver
clocksource: tcb_clksrc: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 115833966437 ns
at_hdmac ffffe600.dma-controller: Atmel AHB DMA Controller ( cpy set slave ), 8 channels
at_hdmac ffffe800.dma-controller: Atmel AHB DMA Controller ( cpy set slave ), 8 channels
AT91: Detected SoC family: sama5d3
AT91: Detected SoC: sama5d31, revision 2
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
at91_i2c f0014000.i2c: using dma0chan0 (tx) and dma0chan1 (rx) for DMA transfers
at91_i2c f0014000.i2c: AT91 i2c bus driver (hw version: 0x402).
clocksource: Switched to clocksource tcb_clksrc
NET: Registered protocol family 2
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes)
TCP established hash table entries: 1024 (order: 0, 4096 bytes)
TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 1024 bind 1024)
UDP hash table entries: 256 (order: 0, 4096 bytes)
UDP-Lite hash table entries: 256 (order: 0, 4096 bytes)
NET: Registered protocol family 1
Initialise system trusted keyrings
workingset: timestamp_bits=30 max_order=14 bucket_order=0
Key type asymmetric registered
Asymmetric key parser 'x509' registered
io scheduler noop registered (default)
io scheduler mq-deadline registered
io scheduler kyber registered
f001c000.serial: ttyS1 at MMIO 0xf001c000 (irq = 22, base_baud = 4125000) is a ATMEL_SERIAL
ffffee00.serial: ttyS0 at MMIO 0xffffee00 (irq = 30, base_baud = 8250000) is a ATMEL_SERIAL
console [ttyS0] enabled
loop: module loaded
ssc f0008000.ssc: Atmel SSC device at 0x6a12493c (irq 19)
ssc f0008000.ssc: failed to auto-setup ssc for audio
at24 0-0051: 8192 byte 24c64 EEPROM, writable, 32 bytes/write
at24 0-0050: 256 byte 24c02 EEPROM, writable, 16 bytes/write
[drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[drm] No driver support for vblank timestamp query.
atmel-hlcdc-display-controller atmel-hlcdc-dc: failed to create HLCDC outputs: -517
atmel-hlcdc-display-controller atmel-hlcdc-dc: failed to initialize mode setting
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
ehci-atmel: EHCI Atmel driver
atmel_usba_udc 500000.gadget: MMIO registers at 0xf8030000 mapped at ff1022ba
atmel_usba_udc 500000.gadget: FIFO at 0x00500000 mapped at 3b2532b1
g_serial gadget: Gadget Serial v2.4
g_serial gadget: g_serial ready
at91_rtc fffffeb0.rtc: registered as rtc0
at91_rtc fffffeb0.rtc: AT91 Real Time Clock driver.
i2c /dev entries driver
AT91: Starting after wakeup
atmel_mci f0000000.mmc: version: 0x505
atmel_mci f0000000.mmc: using dma0chan2 for DMA transfers
atmel_mci f0000000.mmc: Atmel MCI controller at 0xf0000000 irq 18, 1 slots
atmel_aes f8038000.aes: version: 0x135
atmel_aes f8038000.aes: Atmel AES - Using dma1chan0, dma1chan1 for DMA transfers
atmel_sha f8034000.sha: version: 0x410
atmel_sha f8034000.sha: using dma1chan2 for DMA transfers
atmel_sha f8034000.sha: Atmel SHA1/SHA256/SHA224/SHA384/SHA512
atmel_tdes f803c000.tdes: version: 0x701
atmel_tdes f803c000.tdes: using dma1chan3, dma1chan4 for DMA transfers
atmel_tdes f803c000.tdes: Atmel DES/TDES
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xac
nand: Micron MT29F4G08ABBDAHC
nand: 512 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB size: 64
Bad block table found at page 262080, version 0x01
Bad block table found at page 262016, version 0x01
6 ofpart partitions found on MTD device atmel_nand
Creating 6 MTD partitions on "atmel_nand":
0x000000000000-0x000000040000 : "at91bootstrap"
0x000000040000-0x0000000c0000 : "bootloader"
0x0000000c0000-0x000000180000 : "bootloader env"
0x000000180000-0x000000200000 : "device tree"
0x000000200000-0x000000800000 : "kernel"
0x000000800000-0x000010000000 : "rootfs"
NET: Registered protocol family 10
Segment Routing with IPv6
sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
NET: Registered protocol family 17
Loading compiled-in X.509 certificates
[drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[drm] No driver support for vblank timestamp query.
atmel-hlcdc-display-controller atmel-hlcdc-dc: fb0:  frame buffer device
[drm] Initialized atmel-hlcdc 1.0.0 20141504 for atmel-hlcdc-dc on minor 0
UBI error: cannot open mtd 6, error -19
input: gpio-keys as /devices/platform/gpio-keys/input/input0
at91_rtc fffffeb0.rtc: setting system clock to 2007-01-01 00:00:08 UTC (1167609608)
panel-VCC: disabling
panel-VDD: disabling
atmel_usart ffffee00.serial: using dma1chan5 for rx DMA transfers
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
CPU: 0 PID: 1 Comm: swapper Not tainted 4.15.0-rc8-next-20180116 #208
Hardware name: Atmel SAMA5
[<c010cc5c>] (unwind_backtrace) from [<c010b140>] (show_stack+0x10/0x14)
[<c010b140>] (show_stack) from [<c0115f20>] (panic+0xc8/0x254)
[<c0115f20>] (panic) from [<c0801348>] (mount_block_root+0x23c/0x2f8)
[<c0801348>] (mount_block_root) from [<c0801528>] (prepare_namespace+0xa8/0x19c)
[<c0801528>] (prepare_namespace) from [<c0800ff0>] (kernel_init_freeable+0x1bc/0x1cc)
[<c0800ff0>] (kernel_init_freeable) from [<c051b958>] (kernel_init+0x8/0x10c)
[<c051b958>] (kernel_init) from [<c01010e8>] (ret_from_fork+0x14/0x2c)
Exception stack(0xc3821fb0 to 0xc3821ff8)
1fa0:                                     00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)


I bisected it to:

4ac9222778478a00c7fc9d347b7ed1e0e595120d is the first bad commit
commit 4ac9222778478a00c7fc9d347b7ed1e0e595120d
Author: RafaÅ MiÅecki <rafal@xxxxxxxxxx>
Date:   Thu Jan 4 08:05:34 2018 +0100

    mtd: ofpart: add of_match_table with "fixed-partitions"

    This allows using this parser with any flash driver that takes care of
    setting of_node (using mtd_set_of_node helper) correctly. Up to now
    support for "fixed-partitions" DT compatibility string was working only
    with flash drivers that were specifying "ofpart" (manually or by letting
    mtd use the default set of parsers).

    This matches existing bindings documentation.

    Signed-off-by: RafaÅ MiÅecki <rafal@xxxxxxxxxx>
    Reviewed-by: Brian Norris <computersforpeace@xxxxxxxxx>
    Tested-by: Brian Norris <computersforpeace@xxxxxxxxx>
    Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>


Reverting that patch on top of next-20180116 fixes the problem.

I'm using the arch/arm/boot/dts/at91-nattis-2-natte-2.dts device tree which for
the record is kind of new in the upstream kernel, but I have been using that dts
for a while previously. However, I'd put my money on at91-tse850-3.dts also
being affected, and that one have been upstream for a while. Haven't tested the
tse850 device tree though...

Cheers,
Peter