Hi, In the kmemcheck code I take a lot of page faults from any kernel context (with interrupts enabled or disabled). This means that there are a lot of things I can't do. Taking locks is dangerous while handling a page fault occurring in interrupt context. In addition to this, I must _not_ access any memory allocated by kmalloc(), as this may generate a new (recursive) page fault. Currently, I am deferring work to be done later by using a timer that triggers every HZ. This allows me to do what I want in the right context, e.g. interrupts enabled and no locks taken. However, the timer triggers even when I don't need it, and once a second is usually too slow when I actually do need it. So I am looking for a way to schedule my deferred work as soon as interrupts are disabled in the context that caused a page fault. I was reading Matthew Wilcox's paper on softirqs, tasklets, bottom halves, task queues, work queues, and timers. But I am still a little unsure of the best way to proceed. My requirement of not accessing dynamically allocated memory seem unprecedented in the kernel. E.g., one of my earliest attempts included using a kernel thread and waking it up from the page fault handler, but this did not work because adding the kthread to a runqueue would access dynamically allocated memory. Does it seem like softirqs or tasklets can do what I want? Help is much appreciated. Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036 -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
