Re: [PATCH v1 05/18] mm: improve folio_likely_mapped_shared() using the mapcount of large folios

From: Yin, Fengwei
Date: Fri Apr 19 2024 - 10:07:25 EST




On 4/10/2024 3:22 AM, David Hildenbrand wrote:
We can now read the mapcount of large folios very efficiently. Use it to
improve our handling of partially-mappable folios, falling back
to making a guess only in case the folio is not "obviously mapped shared".

We can now better detect partially-mappable folios where the first page is
not mapped as "mapped shared", reducing "false negatives"; but false
negatives are still possible.

While at it, fixup a wrong comment (false positive vs. false negative)
for KSM folios.

Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>

Reviewed-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>