accessing stack of non-current task

shankarvk · 04-20-2010, 06:53 AM

Hi,

Is it possible for the kernel to access the user-stack data of a
task different from "current" ?

I thought the answer is "no". ( Kernel sees memory through the page-table of "current" )

But I found few places in kernel where this is done. ( eg: debug_rt_mutex_print_deadlock() in rtmutex-debug.c )

What is the explanation ?

thanks

jlinkels · 04-20-2010, 09:20 PM

The kernel can do this, why not? The kernel is able to access all memory of user processes otherwise context switches would not be possible. The kernel runs in a different permission space than user programs (kernel space vs user space)

jlinkels

shankarvk · 04-28-2010, 05:33 AM

this answer is incorrect..

jlinkels · 04-28-2010, 05:45 AM

So? What is the correct answer?

jlinkels