2.5.68 oops booting with initrd

Very small and simple kernel configuration (includes devfs, which is where this problem came from), using Etherboot to load it along with a small (768K) initrd.

Unable to handle kernel NULL pointer dereference at virtual address 00000000
 printing eip:
c0109835
*pde = 00000000
Oops: 0002 [#1]
CPU:    0
EIP:    0060:[<c0109835>]    Not tainted
EFLAGS: 00010002

EIP is at __down+0x55/0xc0
eax: 00000000 ebx: c021c190 ecx: c021c190 edx: c151de5c
esi: 00000286 edi: dfece040 ebp: c021c198 esp: c151de50
ds: 007b es: 007b ss: 0068
Process swapper (pid: 1, threadinfo=c151c000 task=dfece040)

Stack: 00000001 dfece040 c0114000 c021c198 00000000 63736900 69642f73 00306373
       c154bd80 00000000 c154be6c dfcfe6c0 c01099cc c021c190 c021c180 
00000000
       c01772d9 c154be40 c01a292a dff228a0 c154bd80 dff294c0 c017722c 
c021c180
Call Trace:
 [<c0114000>] default_wake_function+0x0/0x20
 [<c01099cc>] __down_failed+0x8/0xc
 [<c01772d9>] .text.lock.util+0x55/0x7c
 [<c01a292a>] blk_unregister_region+0x9a/0xa0
 [<c017722c>] devfs_remove_partitions+0x3c/0x50
 [<c01687ed>] del_gendisk+0xfd/0x100
 [<c01a567f>] initrd_release+0x3f/0x70
 [<c014002b>] __fput+0x9b/0xa0
 [<c013e8bd>] filp_close+0x4d/0x80
 [<c013e940>] sys_close+0x50/0x60
 [<c010a98b>] syscall_call+0x7/0xb
 [<c026b6dd>] rd_load_image+0xbd/0x390
 [<c026be96>] initrd_load+0x56/0x80
 [<c026ae93>] prepare_namespace+0x33/0x120
 [<c010506a>] init+0x2a/0x140
 [<c0105040>] init+0x0/0x140
 [<c0108a3d>] kernel_thread_helper+0x5/0x18

Code: 89 10 89 44 24 10 ff 43 04 89 f6 8b 43 04 48 01 03 0f 98 c0
 <0>Kernel panic: Attempted to kill init!

.config is as follows:

CONFIG_X86=y
CONFIG_MMU=y
CONFIG_UID16=y
CONFIG_GENERIC_ISA_DMA=y
CONFIG_EXPERIMENTAL=y
CONFIG_SWAP=y
CONFIG_X86_PC=y
CONFIG_MK7=y
CONFIG_X86_CMPXCHG=y
CONFIG_X86_XADD=y
CONFIG_RWSEM_XCHGADD_ALGORITHM=y
CONFIG_X86_WP_WORKS_OK=y
CONFIG_X86_INVLPG=y
CONFIG_X86_BSWAP=y
CONFIG_X86_POPAD_OK=y
CONFIG_X86_GOOD_APIC=y
CONFIG_X86_USE_PPRO_CHECKSUM=y
CONFIG_X86_USE_3DNOW=y
CONFIG_X86_TSC=y
CONFIG_NOHIGHMEM=y
CONFIG_PCI=y
CONFIG_PCI_GODIRECT=y
CONFIG_PCI_DIRECT=y
CONFIG_PCI_NAMES=y
CONFIG_HOTPLUG=y
CONFIG_KCORE_ELF=y
CONFIG_BINFMT_ELF=y
CONFIG_BLK_DEV_RAM=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_IDE=y
CONFIG_BLK_DEV_IDE=y
CONFIG_BLK_DEV_IDEDISK=y
CONFIG_IDEDISK_MULTI_MODE=y
CONFIG_BLK_DEV_IDECD=y
CONFIG_BLK_DEV_IDEFLOPPY=y
CONFIG_BLK_DEV_IDEPCI=y
CONFIG_IDEPCI_SHARE_IRQ=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
CONFIG_IDEDMA_PCI_AUTO=y
CONFIG_BLK_DEV_IDEDMA=y
CONFIG_BLK_DEV_ADMA=y
CONFIG_IDEDMA_AUTO=y
CONFIG_SCSI=y
CONFIG_BLK_DEV_SD=y
CONFIG_MD=y
CONFIG_BLK_DEV_DM=y
CONFIG_INPUT=y
CONFIG_SOUND_GAMEPORT=y
CONFIG_SERIO=y
CONFIG_SERIO_I8042=y
CONFIG_INPUT_KEYBOARD=y
CONFIG_KEYBOARD_ATKBD=y
CONFIG_VT=y
CONFIG_VT_CONSOLE=y
CONFIG_HW_CONSOLE=y
CONFIG_SERIAL_8250=y
CONFIG_SERIAL_8250_CONSOLE=y
CONFIG_SERIAL_CORE=y
CONFIG_SERIAL_CORE_CONSOLE=y
CONFIG_FAT_FS=y
CONFIG_MSDOS_FS=y
CONFIG_VFAT_FS=y
CONFIG_PROC_FS=y
CONFIG_DEVFS_FS=y
CONFIG_DEVFS_MOUNT=y
CONFIG_TMPFS=y
CONFIG_RAMFS=y
CONFIG_MSDOS_PARTITION=y
CONFIG_NLS=y
CONFIG_VGA_CONSOLE=y
CONFIG_DUMMY_CONSOLE=y
CONFIG_USB=y
CONFIG_USB_DEVICEFS=y
CONFIG_USB_EHCI_HCD=y
CONFIG_USB_OHCI_HCD=y
CONFIG_USB_UHCI_HCD=y
CONFIG_USB_PRINTER=y
CONFIG_USB_STORAGE=y
CONFIG_DEBUG_KERNEL=y
CONFIG_KALLSYMS=y
CONFIG_X86_BIOS_REBOOT=y

After sleeping on it I realized this problem may have been caused by neglecting to compile ext2 into the kernel (the initrd is an ext2 image). Unfortunately, that is not the solution, the oops still occurs.

This should fix it.

Debian GNU/Linux 3.0 is out! ( http://www.debian.org/ )
Email:  Herbert Xu ~{PmV>HI~} <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
--
Index: fs/partitions/check.c
===================================================================
RCS file: /home/gondolin/herbert/src/CVS/debian/kernel-source-2.5/fs/partitions/check.c,v
retrieving revision 1.1.1.8
retrieving revision 1.6
diff -u -r1.1.1.8 -r1.6
--- fs/partitions/check.c	7 Apr 2003 17:32:48 -0000	1.1.1.8
+++ fs/partitions/check.c	13 Apr 2003 00:15:54 -0000	1.6
@@ -414,7 +414,8 @@
 	unlink_gendisk(disk);
 	disk_stat_set_all(disk, 0);
 	disk->stamp = disk->stamp_idle = 0;
-	devfs_remove_partitions(disk);
+	if (disk->minors != 1)
+		devfs_remove_partitions(disk);
 	if (disk->driverfs_dev) {
 		sysfs_remove_link(&disk->kobj, "device");
 		sysfs_remove_link(&disk->driverfs_dev->kobj, "block");

The patch you supplied (check disk->minors != 1 before calling devfs_remove_partitions) did not apply do 2.5.68; the code in fs/partitions/check.c has changed since your base version. However, hand-editing to do the same check has solved the problem.

I'll Christoph supply a patch, since he's the one that's been working in that whole devfs area.

And 2.5.58-bk1 is completly different again but should have fixed it.

Make sure you apply the following diff when using devfs, though:

@@ -81,7 +81,7 @@
 {
 	char dirname[64], symlink[16];
 
-	if (disk->devfs_name[0] != '\0')
+	if (disk->devfs_name[0] == '\0')
 		sprintf(disk->devfs_name, "%s/disc%d", disk->disk_name,
 				disk->first_minor >> disk->minor_shift);