Re: free_task_struct() called too early?

Alan Cox
2001-08-10T22:41:21Z

> When a process terminates, it appears that the task structure is freed too
> early. There are memory references to the kernel task area (task_struct and
> stack space) after free_task_struct(p) is called.
>
> If I modify the following line in include/asm-i386/processor.h
>
> #define free_task_struct(p) free_pages((unsigned long) (p), 1) to
> #define free_task_struct(p) memset((void*) (p), 0xf, PAGE_SIZE*2);
> free_pages((unsigned long) (p), 1)
> then kernel will boot to init and lockup on when first task terminates.
>
> Has anyone looked into or aware of this issue?

2.4.8pre fixed a case with semaphores on the stack. It might not be the only
one. Your #define is wrong though, if a single free_task_struct path is an
if you will not do what you expect

do { memset(), free_pages } while(0);

would be safer.

I'd like to know if 2.4.8pre8 does it except on module unload (where it is
still buggy)

Alan