Dear Usman...
Sorry if I can't give complete explanation, but hopefully it's enough...
On Sat, Jun 26, 2010 at 02:31, Usman S. Ansari <uansari@xxxxxxxxx> wrote:
> I have two kernel modules running.
>
> Module 1:
> - struct a
> {
> int val1;
> char *buffer
> ...
> };
>
> - Then in module 1, I have following global declaration
> struct a buf[20];
>
> - Module 1, calls a exported function "module2_function(int *)" from modules 2:
> it passes &buff[0].val1 as a parameter to the module2_functon
>
> Module 2:
> - I assign buff[0].val1 to variable defined as *i
> - I print *i, and see same data which was assigned by module 1, i.e. 0x9595
> - Have following instruction
> - *i = 1;
> - print *i again and new values i.e. 1 is printed
> - after this in less than a second whole freezes
>
> After debugging for whole day, I tried following, which seems to fix this issue
> - I changed struct a buf[20]; to kmalloc
> - now system does not freez
If my eyes doesn't trick me, initially it's both uninitialized and
unallocated. Are we agree here?
So then, when you gave it a value, kernel tries to store it, but
realized the "container" isn't prepared. Unfortunately, kernels
doesn't do page fault the same way we see in user space.
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
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