Wrong PID for busybox init process

Question

I have set up a small embedded linux that uses busybox. I am facing a problem of which I'm not sure if its caused by busybox or the kernel.

The problem is, that the init process does not have process ID 1. Heres the output of ps:

1 root       0:26 [swapper/0]
2 root       0:00 [kthreadd]
3 root       0:00 [ksoftirqd/0]
4 root       0:00 [kworker/0:0]
5 root       0:00 [kworker/0:0H]
6 root       0:00 [kworker/u4:0]
7 root       0:00 [rcu_preempt]
8 root       0:00 [rcu_sched]
...
549 root       0:00 {linuxrc} init
...

I guess the other processes before init are all kernel processes. The reason why this is a problem is that orphaned processes are given the parent process ID 1, which should be the init process, but now this swapper process is receiving them all.

I noticed that something is going wrong when I observed a lot of zombie processes.

So somehow either init must be forced to PID 1, or orphaned processes must be assigned to the correct init PID.

Does anyone have an idea how to do that?

Thanks a lot!

---

Update: Some more information on my setup

The target is an ARM board with a Xilinx Zynq chip. I was using the Xilinx linux Kernel, and compiled busybox myself (v1.20.2).

The command line is:

ramdisk_size=65536 console=ttyPS0,115200 earlyprintk

Here are the bootlogs up to the moment that the init script is started:

Uncompressing Linux... done, booting the kernel.
[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 3.13.0-xilinx (cone@cone-ubuntu) (gcc version 4.8.1 (Sourcery CodeBench Lite 2013.11-53) ) #5 SMP PREEMPT Sun J4
[    0.000000] CPU: ARMv7 Processor [413fc090] revision 0 (ARMv7), cr=18c5387d
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[    0.000000] Machine model: Xilinx Zynq
[    0.000000] bootconsole [earlycon0] enabled
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] PERCPU: Embedded 8 pages/cpu @c101e000 s10176 r8192 d14400 u32768
[    0.000000] Built 1 zonelists in Zone order, mobility grouping on.  Total pages: 130048
[    0.000000] Kernel command line: ramdisk_size=65536 console=ttyPS0,115200 earlyprintk
[    0.000000] PID hash table entries: 2048 (order: 1, 8192 bytes)
[    0.000000] Dentry cache hash table entries: 65536 (order: 6, 262144 bytes)
[    0.000000] Inode-cache hash table entries: 32768 (order: 5, 131072 bytes)
[    0.000000] Memory: 501272K/524288K available (4781K kernel code, 307K rwdata, 1692K rodata, 197K init, 5345K bss, 23016K reserved, 0K hi)
[    0.000000] Virtual kernel memory layout:
[    0.000000]     vector  : 0xffff0000 - 0xffff1000   (   4 kB)
[    0.000000]     fixmap  : 0xfff00000 - 0xfffe0000   ( 896 kB)
[    0.000000]     vmalloc : 0xe0800000 - 0xff000000   ( 488 MB)
[    0.000000]     lowmem  : 0xc0000000 - 0xe0000000   ( 512 MB)
[    0.000000]     pkmap   : 0xbfe00000 - 0xc0000000   (   2 MB)
[    0.000000]     modules : 0xbf000000 - 0xbfe00000   (  14 MB)
[    0.000000]       .text : 0xc0008000 - 0xc065a600   (6474 kB)
[    0.000000]       .init : 0xc065b000 - 0xc068c7c0   ( 198 kB)
[    0.000000]       .data : 0xc068e000 - 0xc06dac78   ( 308 kB)
[    0.000000]        .bss : 0xc06dac84 - 0xc0c13230   (5346 kB)
[    0.000000] Preemptible hierarchical RCU implementation.
[    0.000000]  RCU lockdep checking is enabled.
[    0.000000]  Dump stacks of tasks blocking RCU-preempt GP.
[    0.000000]  RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2.
[    0.000000] NR_IRQS:16 nr_irqs:16 16
[    0.000000] ps7-slcr mapped to e0802000
[    0.000000] zynq_clock_init: clkc starts at e0802100
[    0.000000] Zynq clock init
[    0.000000] sched_clock: 32 bits at 325MHz, resolution 3ns, wraps every 13215283196ns
[    0.000000] ps7-ttc #0 at e0804000, irq=43
[    0.000000] Console: colour dummy device 80x30
[    0.000000] Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
[    0.000000] ... MAX_LOCKDEP_SUBCLASSES:  8
[    0.000000] ... MAX_LOCK_DEPTH:          48
[    0.000000] ... MAX_LOCKDEP_KEYS:        8191
[    0.000000] ... CLASSHASH_SIZE:          4096
[    0.000000] ... MAX_LOCKDEP_ENTRIES:     16384
[    0.000000] ... MAX_LOCKDEP_CHAINS:      32768
[    0.000000] ... CHAINHASH_SIZE:          16384
[    0.000000]  memory used by lock dependency info: 3695 kB
[    0.000000]  per task-struct memory footprint: 1152 bytes
[   13.207599] Calibrating delay loop... 1292.69 BogoMIPS (lpj=6463488)
[   13.207606] pid_max: default: 32768 minimum: 301
[   13.207607] Mount-cache hash table entries: 512
[   13.207609] CPU: Testing write buffer coherency: ok
[   13.207610] CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
[   13.207611] Setting up static identity map for 0x489b98 - 0x489bf0
[   13.207612] L310 cache controller enabled
[   13.207613] l2x0: 8 ways, CACHE_ID 0x410000c8, AUX_CTRL 0x72760000, Cache size: 512 kB
[   13.207627] CPU1: Booted secondary processor
[   13.207641] CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
[   13.207642] Brought up 2 CPUs
[   13.207644] SMP: Total of 2 processors activated.
[   13.207644] CPU: All CPU(s) started in SVC mode.
[   13.207646] devtmpfs: initialized
[   13.207647] VFP support v0.3: implementor 41 architecture 3 part 30 variant 9 rev 4
[   13.207650] regulator-dummy: no parameters
[   13.207651] NET: Registered protocol family 16
[   13.207651] DMA: preallocated 256 KiB pool for atomic coherent allocations
[   13.207654] cpuidle: using governor ladder
[   13.207654] cpuidle: using governor menu
[   13.207658] syscon f8000000.ps7-slcr: regmap [mem 0xf8000000-0xf8000fff] registered
[   13.207660] hw-breakpoint: found 5 (+1 reserved) breakpoint and 1 watchpoint registers.
[   13.207662] hw-breakpoint: maximum watchpoint size is 4 bytes.
[   13.207663] zynq-ocm f800c000.ps7-ocmc: ZYNQ OCM pool: 256 KiB @ 0xe0880000
[   13.207672] bio: create slab <bio-0> at 0
[   13.207674] vgaarb: loaded
[   13.207674] SCSI subsystem initialized
[   13.207675] usbcore: registered new interface driver usbfs
[   13.207676] usbcore: registered new interface driver hub
[   13.207677] usbcore: registered new device driver usb
[   13.207678] media: Linux media interface: v0.10
[   13.207679] Linux video capture interface: v2.00
[   13.207680] pps_core: LinuxPPS API ver. 1 registered
[   13.207681] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[   13.207682] PTP clock support registered
[   13.207683] EDAC MC: Ver: 3.0.0
[   13.207685] DMA-API: preallocated 4096 debug entries
[   13.207686] DMA-API: debugging enabled by kernel config
[   13.207687] Switched to clocksource arm_global_timer
[   13.207696] NET: Registered protocol family 2
[   13.207697] TCP established hash table entries: 4096 (order: 2, 16384 bytes)
[   13.207698] TCP bind hash table entries: 4096 (order: 5, 147456 bytes)
[   13.207699] TCP: Hash tables configured (established 4096 bind 4096)
[   13.207700] TCP: reno registered
[   13.207701] UDP hash table entries: 256 (order: 2, 20480 bytes)
[   13.207702] UDP-Lite hash table entries: 256 (order: 2, 20480 bytes)
[   13.207703] NET: Registered protocol family 1
[   13.207704] RPC: Registered named UNIX socket transport module.
[   13.207705] RPC: Registered udp transport module.
[   13.207706] RPC: Registered tcp transport module.
[   13.207707] RPC: Registered tcp NFSv4.1 backchannel transport module.
[   13.207708] Trying to unpack rootfs image as initramfs...
[   13.207709] rootfs image is not initramfs (no cpio magic); looks like an initrd
[   13.207717] Freeing initrd memory: 6004K (df551000 - dfb2e000)
[   13.207718] hw perfevents: enabled with ARMv7 Cortex-A9 PMU driver, 7 counters available
[   13.207722] jffs2: version 2.2. (NAND) (SUMMARY)  © 2001-2006 Red Hat, Inc.
[   13.207723] msgmni has been set to 990
[   13.207724] io scheduler noop registered
[   13.207724] io scheduler deadline registered
[   13.207725] io scheduler cfq registered (default)
[   13.207728] dma-pl330 f8003000.ps7-dma: unable to set the seg size
[   13.207729] dma-pl330 f8003000.ps7-dma: Loaded driver for PL330 DMAC-2364208
[   13.207731] dma-pl330 f8003000.ps7-dma:      DBUFF-128x8bytes Num_Chans-8 Num_Peri-4 Num_Events-16
[   13.207733] e0001000.serial: ttyPS0 at MMIO 0xe0001000 (irq = 82, base_baud = 3125000) is a xuartps
[   13.207734] console [ttyPS0] enabled
[   13.207734] console [ttyPS0] enabled
[   13.207735] bootconsole [earlycon0] disabled
[   13.207735] bootconsole [earlycon0] disabled
[   13.207737] xdevcfg f8007000.ps7-dev-cfg: ioremap 0xf8007000 to e0866000
[   13.207743] brd: module loaded
[   13.207746] loop: module loaded
[   13.207748] zynq-qspi e000d000.ps7-qspi: master is unqueued, this is deprecated
[   13.207749] zynq-qspi e000d000.ps7-qspi: at 0xE000D000 mapped to 0xE0868000, irq=51
[   13.207752] e1000e: Intel(R) PRO/1000 Network Driver - 2.3.2-k
[   13.207753] e1000e: Copyright(c) 1999 - 2013 Intel Corporation.
[   13.207754] libphy: XEMACPS mii bus: probed
[   13.207755] xemacps e000b000.ps7-ethernet: pdev->id -1, baseaddr 0xe000b000, irq 54
[   13.207757] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[   13.207758] ehci-pci: EHCI PCI platform driver
[   13.207759] ULPI transceiver vendor/product ID 0x0424/0x0007
[   13.207760] Found SMSC USB3320 ULPI transceiver.
[   13.207761] ULPI integrity check: passed.
[   13.207761] zynq-ehci zynq-ehci.0: Xilinx Zynq USB EHCI Host Controller
[   13.207763] zynq-ehci zynq-ehci.0: new USB bus registered, assigned bus number 1
[   13.207769] zynq-ehci zynq-ehci.0: irq 53, io mem 0x00000000
[   13.207772] zynq-ehci zynq-ehci.0: USB 2.0 started, EHCI 1.00
[   13.207773] usb usb1: New USB device found, idVendor=1d6b, idProduct=0002
[   13.207774] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[   13.207775] usb usb1: Product: Xilinx Zynq USB EHCI Host Controller
[   13.207776] usb usb1: Manufacturer: Linux 3.13.0-xilinx ehci_hcd
[   13.207777] usb usb1: SerialNumber: zynq-ehci.0
[   13.207779] hub 1-0:1.0: USB hub found
[   13.207779] hub 1-0:1.0: 1 port detected
[   13.207781] usbcore: registered new interface driver usb-storage
[   13.207782] mousedev: PS/2 mouse device common for all mice
[   13.207783] i2c /dev entries driver
[   13.207784] cdns-i2c e0004000.ps7-i2c: 400 kHz mmio e0004000 irq 57
[   13.207787] xadcps f8007100.ps7-xadc: enabled:       yes     reference:      external
[   13.207788] cdns-wdt f8005000.ps7-wdt: Xilinx Watchdog Timer at e0876000 with timeout 10s
[   13.207790] zynq-edac f8006000.ps7-ddrc: ecc not enabled
[   13.207791] Xilinx Zynq CpuIdle Driver started
[   13.207590] sdhci: Secure Digital Host Controller Interface driver
[   13.207591] sdhci: Copyright(c) Pierre Ossman
[   13.207592] sdhci-pltfm: SDHCI platform and OF driver helper
[   13.207593] sdhci-arasan e0100000.ps7-sdio: dummy supplies not allowed
[   13.207594] mmc0: no vqmmc regulator found
[   13.207595] sdhci-arasan e0100000.ps7-sdio: dummy supplies not allowed
[   13.207596] mmc0: no vmmc regulator found
[   13.207603] mmc0: SDHCI controller on e0100000.ps7-sdio [e0100000.ps7-sdio] using ADMA
[   13.207608] usbcore: registered new interface driver usbhid
[   13.207608] usbhid: USB HID core driver
[   13.207609] TCP: cubic registered
[   13.207610] NET: Registered protocol family 17
[   13.207611] Registering SWP/SWPB emulation handler
[   13.207612] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)
[   13.207614] mmc0: new high speed SDHC card at address 59b4
[   13.207615] mmcblk0: mmc0:59b4 USD   14.7 GiB 
[   13.207617]  mmcblk0: p1 p2
[   13.207618] RAMDISK: gzip image found at block 0
[   13.207691] usb 1-1: new high-speed USB device number 2 using zynq-ehci
[   13.207707] VFS: Mounted root (ext2 filesystem) on device 1:0.
Starting rcS...

@sawdust: I don't have a /init file. I think /linuxrc is the first thing that is executed, and that is just a symlink to busybox.

Answer 1

I think I solved the problem. Apparently, adding root=/dev/ram to the boot parameters does the trick. I saw that being recommended somewhere online, but I can't find the link anymore. I'm not entirely sure why this is necessary, but it works :-)