kernel BUG at arch/i386/mm/highmem.c:63! kunmap_atomic

kernel BUG at arch/i386/mm/highmem.c:63! kunmap_atomic

[Anil kumar]

Hi,

I get the following kernel panic,

kernel BUG at arch/i386/mm/highmem.c:63!
EIP:    0060:[<c011af5a>]    Tainted: PF     VLI
EFLAGS: 00010006   (2.6.11-1.1369_FC4smp)
EIP is at kunmap_atomic+0x35/0x5f

The following is the code, I am using in my driver:

kmap_atomic code:

int hr_km_type = (in_interrupt())? KM_IRQ0: KM_USER0;
         pDataBuffer = kmap_atomic(cur_seg->page,
hr_km_type) + cur_seg->offset;
         if(pDataBuffer == NULL) {
            return (ENOMEM);
         }

kunmap_atomic code:

int hr_km_type = (in_interrupt())? KM_IRQ0: KM_USER0;
                  kunmap_atomic(pDataBuffer -
sg->offset, hr_km_type);

I am not using any locks like irq_disable/restore
before and after calling kmap_atomic/kunmap_atomic.

The system has 1GB memory.

with regards,
   Anil

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Re: kernel BUG at arch/i386/mm/highmem.c:63! kunmap_atomic

[Arjan van de Ven]

On Sun, 2006-03-26 at 09:45 -0800, Anil kumar wrote:
> 
> Hi,
> 
> I get the following kernel panic,
> 
> kernel BUG at arch/i386/mm/highmem.c:63!
> EIP:    0060:[<c011af5a>]    Tainted: PF     VLI
> EFLAGS: 00010006   (2.6.11-1.1369_FC4smp)
> EIP is at kunmap_atomic+0x35/0x5f
> 
> The following is the code, I am using in my driver:
> 
> kmap_atomic code:
> 
> int hr_km_type = (in_interrupt())? KM_IRQ0: KM_USER0;
>          pDataBuffer = kmap_atomic(cur_seg->page,
> hr_km_type) + cur_seg->offset;
>          if(pDataBuffer == NULL) {
>             return (ENOMEM);
>          }
> 

this is buggy; your irq handler may run with interrupts on for example

I fear the worst for your code ;) I would suggest getting more people to
review it (for example on kernel-newbies list or the kernel-mentors
list) before using it in production ;)