Re: Can reverse VM locks?

[Rik van Riel <riel@conectiva.com.br>]

OK, I've been looking at the lock order reversal too,
though for different reasons ;)

On Mon, 2 Jul 2001 markhe@veritas.com wrote:
> On Mon, 2 Jul 2001, Rik van Riel wrote:
> > On Mon, 2 Jul 2001 markhe@veritas.com wrote:
> >
> > >   Anyone know of any places where reversing the lock ordering would break?
> >
> > Basically add_to_page_cache and remove_from_page cache and friends ;)
>
>   Hmm, does a page-cache page need to be on an LRU list?
>
>   If not, the 'add' case falls out OK; add it to the page-cache
> first, then add it to an LRU list _after_ dropping the
> pagecache_lock and taking the pagemap_lru_lock.  ie. no lock
> overlap.

Indeed, this would work. I've been looking at this too.

	[snip cool analysis]
> True?

Yes, very much true.  Now what I wanted to ask about:
do you already have a patch which does this or should
I write a patch which does the lock order reversal ?

cheers,

Rik
--
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