Re: Trying to convert old modules to newer kernels

[Lennart Sorensen]

On Wed, Dec 19, 2007 at 03:10:28PM -0500, linux-os (Dick Johnson) wrote:
> 
> 
> Here is a so-called BUG when trying to insert the following
> module into the kernel (2.6.22.1).
> 
> 
> BUG: unable to handle kernel paging request at virtual address 6814ec83
>   printing eip:
> c016d013
> *pde = 00000000
> Oops: 0000 [#1]
> PREEMPT SMP 
> Modules linked in: MemDev parport_pc lp parport nfsd exportfs lockd sunrpc iptable_filter ip_tables x_tables e1000 e100 mii nls_cp437 msdos fat dm_mod usbhid ff_memless uhci_hcd ehci_hcd video container button battery ac rtc ipv6 ext3 jbd ata_piix libata aic7xxx scsi_transport_spi sd_mod scsi_mod
> CPU:    0
> EIP:    0060:[<c016d013>]    Not tainted VLI
> EFLAGS: 00010046   (2.6.22.1 #2)
> EIP is at kmem_cache_alloc+0x23/0x80
> eax: 00000000   ebx: 00000246   ecx: f8913300   edx: 6814ec83
> esi: 00000000   edi: f8913000   ebp: ef27e000   esp: ef27ff74
> ds: 007b   es: 007b   fs: 00d8  gs: 0033  ss: 0068
> Process insmod (pid: 4593, ti=ef27e000 task=f614f550 task.ti=ef27e000)
> Stack: f8913300 00000000 00000000 f8913013 f7fff880 000000d0 00000000 ef27e000
>         c012b907 ffffffff 00000000 c0140279 bffedc07 bffedc08 0807a018 00000000
>         c0102b82 0807a018 000018c9 0807a008 00000000 00000000 bffeabc8 00000080 
> Call Trace:
>   [<f8913013>] init_module+0x13/0x48 [MemDev]
>   [<c012b907>] blocking_notifier_call_chain+0x17/0x20
>   [<c0140279>] sys_init_module+0xd9/0x140
>   [<c0102b82>] sysenter_past_esp+0x5f/0x85
>   =======================
> Code: 90 8d b4 26 00 00 00 00 83 ec 0c f6 c2 10 89 74 24 04 89 d6 89 7c 24 08 89 c7 89 1c 24 75 49 9c 5b fa 64 a1 04 20 47 c0 8b 14 87 <8b> 02 85 c0 74 25 c7 42 0c 01 00 00 00 48 89 02 8b 54 82 18 53 
> EIP: [<c016d013>] kmem_cache_alloc+0x23/0x80 SS:ESP 0068:ef27ff74
> 
> 
> 
> Here is the code that causes the crash.
> 
> 
> #include <linux/autoconf.h>
> #include <linux/module.h>
> #include <linux/kernel.h>
> #include <linux/init.h>
> #include <linux/poll.h>
> #include <linux/mm.h>
> static const char devname[]="Device";
> #define NR_PAGES 0x10
> 
> struct DMA {
>      void *ptr;
>      unsigned long addr;
>      size_t len;
>      };
> //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> //
> //  The top-level object that gets allocated once, when the module is
> //  installed.
> //
> struct INFO {
>      struct file_operations fa;          // Kernel connection
>      struct semaphore dev_sem;
>      struct DMA dma[NR_PAGES];           // Can map one megabyte
>      uint32_t vm_start;                  // Where mmap() starts
>      uint32_t pages;                     // Number of pages mapped
>      atomic_t open;                      // Number of opens
>      };
> //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> static struct INFO *info;
> //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> //
> //   Initialize the module and return 0 if everything is okay.
> //   Return a negative error-code if not.
> //
> static int32_t startup()
> {
>      if((info = kmalloc(sizeof(struct INFO), GFP_KERNEL)) == NULL) {
>          printk(KERN_ALERT"%s : Can't allocate memory\n", devname);

Missing space after KERN_ALERT?

>          return -ENOMEM;
>      }
>      return 0;
> }
> //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> //
> //  Cleanup the module in preparation for removal.
> //
> static void quit() {
>      kfree(info);
>      printk(KERN_INFO"%s : Module removed\n", devname);
> }
> MODULE_LICENSE("GPL");
> MODULE_ALIAS("MemDev");
> module_init(startup);
> module_exit(quit);
> //-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
> 
> Anybody have a clue why this should error out? Am I using
> some reserved names??? I got rid of __init and anything
> else that I thought could cause the fault, plus got rid
> of all the code!

--
Len Sorensen
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