thp: remove PG_buddy

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PG_buddy can be converted to _mapcount == -2.  So the PG_compound_lock can
be added to page->flags without overflowing (because of the sparse section
bits increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y.  This also
has to move the memory hotplug code from _mapcount to lru.next to avoid
any risk of clashes.  We can't use lru.next for PG_buddy removal, but
memory hotplug can use lru.next even more easily than the mapcount
instead.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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Andrea Arcangeli 2011-01-13 15:47:00 -08:00 • committed by Linus Torvalds

parent 21ae5b0175

commit 5f24ce5fd3

7 changed files with 52 additions and 29 deletions

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14

include/linux/memory_hotplug.h

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21

include/linux/mm.h

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7

include/linux/page-flags.h

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