swap_info: note SWAP_MAP_SHMEM

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While we're fiddling with the swap_map values, let's assign a particular
value to shmem/tmpfs swap pages: their swap counts are never incremented,
and it helps swapoff's try_to_unuse() a little if it can immediately
distinguish those pages from process pages.

Since we've no use for SWAP_MAP_BAD | COUNT_CONTINUED,
we might as well use that 0xbf value for SWAP_MAP_SHMEM.

Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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This commit is contained in:

Hugh Dickins 2009-12-14 17:58:47 -08:00 • committed by Linus Torvalds

parent 570a335b8e

commit aaa468653b

3 changed files with 42 additions and 22 deletions

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6

include/linux/swap.h

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11

mm/shmem.c

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47

mm/swapfile.c

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