Re: reduce shrink_mmap rate of failure (initial attempt)

[Roger Larsson <roger.larsson@optronic.se>]

>That patch hangs my machine here when I run mmap002.  The machine is
>in shrink_mmap.  It hangs trying to get the pagmap_lru_lock.
>
>I think that the idea is good, but it doesn't work here :(.
>
>Later, Juan.


Ouch...

The only possible explaination is that we are searching for pages on a zone.
But no such pages are possible to free from LRU...
And we LOOP the list, holding the lru lock...
Note: without this patch you may end up in another bad situation where
shrink_mmap always fails and swapping will start until it swaps out a page
of that specific zone.
And without the test? We would free all other LRU pages without finding one
that we want :-(

This will be interesting to fix...

May the allocation of pages play a part? Filling zone after zone will give no
mix between the zones.

/RogerL
(from work)

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