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From: Andrea Arcangeli <andrea@suse.de>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Linux MM <linux-mm@kvack.org>,
	Linux Kernel <linux-kernel@vger.rutgers.edu>
Subject: Re: 2.2.1{3,4,5pre*} VM bug found
Date: Tue, 25 Jan 2000 19:15:43 +0100 (CET)	[thread overview]
Message-ID: <Pine.LNX.4.10.10001251906370.14600-100000@d251.suse.de> (raw)
In-Reply-To: <Pine.LNX.4.10.10001250421090.482-100000@mirkwood.dummy.home>

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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  reply	other threads:[~2000-01-25 18:15 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2000-01-25  3:27 Rik van Riel
2000-01-25 18:15 ` Andrea Arcangeli [this message]
2000-01-26  0:48   ` Rik van Riel
2000-01-27 19:09     ` Stephen C. Tweedie
2000-01-27 19:07 ` Stephen C. Tweedie

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