Hi All, I am trying to put kernel thread to sleep via interruptible_sleep_on_timeout(). Body of kernel thread function is as follows static int print_taskinfo(void * data) { wait_queue_head_t wait; init_waitqueue_head (&wait); for (;;) { // do something useful here. interruptible_sleep_on_timeout(&wait, HZ); //check whether we have to break loop or continue. } } I am facing following kernel oops : Unable to handle kernel NULL pointer dereference at virtual address 00000005 printing eip: c011905d *pde = 00000000 Oops: 0002 CPU: 0 EIP: 0060:[<c011905d>] Tainted: PF EFLAGS: 00010086 EIP is at interruptible_sleep_on_timeout [kernel] 0x2d (2.4.20-6) eax: c2cadfc4 ebx: 00000286 ecx: c2cadfac edx: 00000001 esi: 00000064 edi: c8dc7540 ebp: c2cadfbc esp: c2cadfa4 ds: 0068 es: 0068 ss: 0068 Process insmod (pid: 3884, stackpage=c2cad000) Stack: 00000000 c2cac000 00000f2b 00000000 c034c000 c8dc74c0 c2cadfec d087d1a1 00000001 c2cadfc8 c2cadfc8 00000000 00000000 00000000 00000000 d087d074 00000000 00000000 00000000 c010742d 00000000 00000000 00000000 Call Trace: [<d087d1a1>] print_taskinfo [hello1] 0x12d (0xc2cadfc0)) [<d087d074>] print_taskinfo [hello1] 0x0 (0xc2cadfe0)) [<c010742d>] kernel_thread_helper [kernel] 0x5 (0xc2cadff0)) Can anyone guide me where I am going wrong? Regards Dinesh __________________________________________________________ Yahoo! India Answers: Share what you know. Learn something new http://in.answers.yahoo.com/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/