Re: vm related lock up in 2.6.15

From: Dave Jones
Date: Mon Jan 09 2006 - 11:34:00 EST


On Mon, Jan 09, 2006 at 08:32:20AM -0800, Linus Torvalds wrote:

> > Turns out this was your BUG_ON(page_count(p) <= page_mapcount(p));
> > addition to putpage_test_zero, which I added a few days ago and promptly
> > forgot about.
> >
> > Triggering this isn't too difficult it seems :-/
>
> Well, as I warned in the message that had the patch, the test _is_ racy.
> The reads of the page counts have no serialization, so if another process
> is changing them, I don't guarantee that the test is correct.
>
> IOW, it was meant as a special case debug test for one particular problem
> where I hoped it would give more information, rather than a real patch.

ok, that explains. I'll go back to chasing the real cause of the corruption
I was seeing :-/

Dave

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