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Does each thread have its own kernel stack?
Each process has a kernel stack (or more generally, each thread has its own stack) Just like there has to be a separate place for each process to hold its set of saved registers (in its process table entry), each process also needs its own kernel stack, to work as its execution stack when it is executing in the kernel.
Where is thread stack allocated?
Either thread stack memory is allocated by the operating system as part of the system call that creates a thread, or the process creating the thread has to provide memory from the application heap to be used as thread stack.
What is the advantage of having a separate kernel stack and user stack?
With separate user and kernel stacks for each process or thread, we have better isolation. Problems in the user stack can’t cause a crash in the kernel. This isolation makes the kernel more secure because it only trusts the stack area that is under its control.
Why does the Linux kernel use a separate stack?
Happens when the kernel is very confused (e.g. kernel stack pointer corrupt). Using a separate stack allows the kernel to recover from it well enough in many cases to still output an oops. ESTACK_NMI.
Can a kernel thread be split across multiple CPUs?
However, if a blocking system call is made, then the entire process blocks, even if the other user threads would otherwise be able to continue. Because a single kernel thread can operate only on a single CPU, the many-to-one model does not allow individual processes to be split across multiple CPUs.
How big is the kernel stack in x86 _ 64?
Like all other architectures, x86_64 has a kernel stack for every active thread. These thread stacks are THREAD_SIZE (2*PAGE_SIZE) big. These stacks contain useful data as long as a thread is alive or a zombie. While the thread is in user space the kernel stack is empty except for the thread_info structure at the bottom.
Is the per thread stack empty in Linux?
These stacks contain useful data as long as a thread is alive or a zombie. While the thread is in user space the kernel stack is empty except for the thread_info structure at the bottom. In addition to the per thread stacks, there are specialized stacks associated with each CPU.