rmmod mtd driver produces a segmentation fault
thierry.chantry at lotsys.com
thierry.chantry at lotsys.com
Tue Mar 22 04:07:18 EST 2005
Hello,
Does this post is so stupid that nobody wants to give us a short
explanation ?
Thanks
Thierry Chantry
-------- Posted on Thu Mar 10 07:07:15 EST 2005 ------------
Sent by Thierry Chantry on behalf Vincent Laporte:
HARDWARE
- Standard PC motherboard
SOFTWARE configuration:
- Fedora Core 2 distribution
- Vanilla Kernel 2.6.7
- MTD version provided with the above vanilla kernel
Hi all,
I'm writing two MTD drivers to manage specific SRAM and FLASH devices.
All works well until I try to remove both modules. The problem is
systematic,
you have just to insert two mtd drivers (with insmod) and then remove them
with
rmmod.
Find bellow a sample and its makefile to help you to reproduce the problem.
To reproduce the problem run the following commands:
modprobe mtdram (your test drivers)
modprobe mtdblock (it is necessary to reproduce the bug)
insmod mtd_sram.ko (my driver)
rmmod mtd_sram
rmmod mtdram
The last rmmod produces a page fault. It seems that the bug is located in
the
block device managment because if mtdblock isn't loaded everything works
well.
You'll find bellow a dmesg result after the page fault.
I have also tested the MTD version embedded in the Fedora Core 2 kernel
(2.6.10-1.12_FC2).
I guess the isn't a very old version of the MTD layer. The problem still
exist with that version.
Can you help me to solve that problem ?
Thanks a lot for your help.
Regards,
Vincent Laporte
############ MY SAMPLE ################################
#include <linux/mtd/mtd.h>
static struct mtd_info sMyMtd;
//****************************************************************************
static int DeviceRead(struct mtd_info *psMtd, loff_t From, size_t Len,
size_t *pRetlen, u_char *pucBuf)
{
printk("SRAM(%d) : DeviceRead.\n", __LINE__);
return 0;
}
//****************************************************************************
static int DeviceWrite(struct mtd_info *psMtd, loff_t To, size_t Len,
size_t *pRetlen, const u_char *pucBuf)
{
printk("SRAM(%d) : DeviceWrite.\n", __LINE__);
return 0;
}
//****************************************************************************
static int __init init_mtdsram(void)
{
int iRet = 0;
printk("SRAM(%d) : Init begin.\n", __LINE__);
memset(&sMyMtd, 0, sizeof(sMyMtd));
sMyMtd.name = "MTDSRAM#1";
sMyMtd.type = MTD_RAM;
sMyMtd.flags = MTD_CAP_RAM;
sMyMtd.size = 1024 * 1024;
sMyMtd.read = DeviceRead;
sMyMtd.write = DeviceWrite;
iRet = add_mtd_device (&sMyMtd);
printk("SRAM(%d) : iRet begin return %d.\n", __LINE__, iRet);
return iRet;
}
//****************************************************************************
static void __exit cleanup_mtdsram(void)
{
int iRet = 0;
printk("SRAM(%d) : Release begin.\n", __LINE__);
iRet = del_mtd_device(&sMyMtd);
printk("SRAM(%d) : iRet release return %d.\n", __LINE__, iRet);
}
module_init(init_mtdsram);
module_exit(cleanup_mtdsram);
############ EOF MY SAMPLE #############################
############ MY MAKEFILE ###############################
ifeq ($(KLINUX_TARGET),)
KLINUX_TARGET:=/lib/modules/`uname -r`/build
endif
# If KERNEL_RELEASE defined we are in the MAKE processus
# otherwise the make command has just been launched
ifneq ($(KERNELRELEASE),)
obj-m := mtd_sram.o
mtd_sram-objs := mtd_sram.module.o
EXTRA_CFLAGS += -Wall
else
default:
$(MAKE) -C $(KLINUX_TARGET) SUBDIRS=`pwd` modules
# $(MAKE) -C $(KLINUX_TARGET) SUBDIRS=`pwd` KBUILD_VERBOSE=1 modules
clean:
rm -rf *.o *.ko *.mod.c
endif
############ EOF MY MAKEFILE ############################
############ DMESG after the crash ############################
mtd_sram: module license 'unspecified' taints kernel.
SRAM(28) : Init begin.
SRAM(41) : iRet begin return 0.
SRAM(51) : Release begin.
SRAM(55) : iRet release return 0.
------------[ cut here ]------------
kernel BUG at include/linux/dcache.h:276!
invalid operand: 0000 [#1]
Modules linked in: mtdram mtdblock mtd_blkdevs mtdchar mtdcore
snd_mixer_oss
snd soundcore parport_pc lp parport autofs4 smbfs rfcomm l2cap bluetooth
sunrpc e100 mii floppy sg scsi_mod
microcode usblp dm_mod joydev mtouchusb uhci_hcd usbcore ipv6 ext3 jbd
CPU: 0
EIP: 0060:[<c01802c8>] Tainted: P
EFLAGS: 00010246 (2.6.7)
EIP is at sysfs_remove_dir+0xe8/0x100
eax: 00000000 ebx: cefc507c ecx: c0206e90 edx: 00000000
esi: c135dc00 edi: d03af618 ebp: c135fd58 esp: cfdabedc
ds: 007b es: 007b ss: 0068
Process rmmod (pid: 3521, threadinfo=cfdaa000 task=d07759f0)
Stack: cefc507c c135dc00 c135dcdc c01aa7c6 cefc507c c01aa7d8 cefc502c
c020237f
cefc502c c0205cbf c135dc00 d89cc56c c0206a38 c135dc00 c017d6af
d3350a54
d89cc574 d89c7792 d3350a54 d89cb768 d89cc56c d89c7810 d89cc540
d89c92f0
Call Trace:
[<c01aa7c6>] kobject_del+0x16/0x20
[<c01aa7d8>] kobject_unregister+0x8/0x10
[<c020237f>] elv_unregister_queue+0xf/0x30
[<c0205cbf>] blk_unregister_queue+0x2f/0x50
[<c0206a38>] unlink_gendisk+0x8/0x20
[<c017d6af>] del_gendisk+0x4f/0xc0
[<d89c7792>] del_mtd_blktrans_dev+0x52/0x60 [mtd_blkdevs]
[<d89cb768>] mtdblock_remove_dev+0x8/0x10 [mtdblock]
[<d89c7810>] blktrans_notify_remove+0x70/0x80 [mtd_blkdevs]
[<d89c1155>] del_mtd_device+0x85/0xf0 [mtdcore]
[<c012ec7c>] __try_stop_module+0x1c/0x30
[<c012c906>] try_stop_module+0x16/0x20
[<d898b2c5>] cleanup_mtdram+0x15/0x35 [mtdram]
[<c012cabe>] sys_delete_module+0x11e/0x170
[<c014291a>] unmap_vma_list+0x1a/0x30
[<c0142c69>] do_munmap+0x109/0x150
[<c01168b0>] do_page_fault+0x0/0x4cc
[<c0105cad>] sysenter_past_esp+0x52/0x71
Code: 0f 0b 14 01 46 a7 2c c0 e9 23 ff ff ff 5b 5e 5f c3 8d b4 26
############ EOF DMESG after the crash ############################
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