Re: bad page state in 3.13-rc4

From: Christoph Lameter
Date: Thu Dec 19 2013 - 10:41:57 EST


On Wed, 18 Dec 2013, Linus Torvalds wrote:

> Somebody who knows the migration code needs to look at this. ChristophL?

Its been awhile sorry and there has been a huge amount of work done on top
of my earlier work. Cannot debug that anymore and I am finding myself in
the role of the old guy who just complains a lot. Some of that
functionality seems bizarre to me like the on the fly conversion between
huge pages and regular pages, weird and complex page count handling etc
etc.

The last time I looked at the code I was horrified to find that the new
huge page migration does not use migration ptes to create a cooldown phase
but directly swaps the pmd. That used to cause huge problems with regular
pages in the past. But I was told that was all safe. Mel?
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