Re: Oops in __free_pages_ok (pre7-1) (Long) (backtrace)

[Linus Torvalds <torvalds@transmeta.com>]

On Wed, 3 May 2000, Kanoj Sarcar wrote:
> > So "is_page_shared()" can be entirely crap. And can tell shrink_mmap()
> 
> Not really ... look at other places that call is_page_shared, they all
> hold the pagelock. shrink_mmap does not bother with is_page_shared logic.

That wasn't my argument.

My argument is that yes, the _callers_ of is_page_shared() all hold the
page lock. No question about that. But the things that is_page_shared()
actually tests can be modified without holding the page lock, so the page
lock doesn't actually _protect_ it. See?

So the callers might as well hold one of the networking spinlocks - it
just doesn't matter as a lock, because the places that modify the stuff do
not care about the lock.. And that is fishy.

		Linus

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