On Fri, Feb 24, 2012 at 4:47 AM, KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> wrote: > How protect this loop from task exiting? AFAIK, while_each_thread > require rcu_read_lock or task_list_lock. I missed this, thanks. I'll send a patch for this on top of my earlier patch since Andrew has already included the earlier patch. > Sigh. No, I missed one thing. If application use > makecontext()/swapcontext() pair, > ESP is not reliable way to detect pthread stack. At that time the > stack is still marked > as anonymous memory. This is not wrong, because it essentially gives the correct picture of the state of that task -- the task is using another vma as a stack during that point and not the one it was allotted by pthreads during thread creation. I don't think we can successfully stick to the idea of trying to mark stack space allocated by pthreads but not used by any task *currently* as stack as long as the allocation happens outside the kernel space. The only way to mark this is either by marking the stack as VM_GROWSDOWN (which will make the stack grow and break some pthreads functions) or create a new flag, which a simple display such as this does not deserve. So it's best that this sticks to what the kernel *knows* is being used as stack. -- Siddhesh Poyarekar http://siddhesh.in -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>