2.2.1{3,4,5pre*} VM bug found

[Andrea Arcangeli]

On Tue, 25 Jan 2000, Rik van Riel wrote:

>calls __get_free_pages(). When we're (almost) out of
>memory, the process will wake up kswapd and try to

You'll block also before to go out of memory if the allocation rate is
high enough.

>In 2.2.15pre4 or when the call to try_to_free_pages()
>generates disk I/O, the task will call schedule().
>Since the task state != TASK_RUNNABLE, schedule() will
>immedately remove it from the run queue ...

Before calling schedule() you always gets registered in a waitqueue so
you can't deadlock or wait too much.

If something there is the opposite problem. If you do:

	__set_current_state(TASK_UNINTERRUPTIBLE);
	get_page(GFP_KERNEL);
	XXXXXXXXXXXXXXXXXXXX
	schedule();

then at point XXXXXXX you may become a task running and you don't block
anymore.

Andrea


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