Re: [patch 8/8] mm: reduce rmap overhead for ex-KSM page copies createdon swap faults

From: Rik van Riel
Date: Wed Dec 12 2012 - 17:37:42 EST

On 12/12/2012 04:43 PM, Johannes Weiner wrote:
When ex-KSM pages are faulted from swap cache, the fault handler is
not capable of re-establishing anon_vma-spanning KSM pages. In this
case, a copy of the page is created instead, just like during a COW

These freshly made copies are known to be exclusive to the faulting
VMA and there is no reason to go look for this page in parent and
sibling processes during rmap operations.

Use page_add_new_anon_rmap() for these copies. This also puts them on
the proper LRU lists and marks them SwapBacked, so we can get rid of
doing this ad-hoc in the KSM copy code.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

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