mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined

mm: clear node in N_HIGH_MEMORY and stop kswapd when all memory is offlined

When memory is hot-removed, its node must be cleared in N_HIGH_MEMORY if
there are no present pages left.

In such a situation, kswapd must also be stopped since it has nothing left
to do.

Signed-off-by: David Rientjes <[email protected]>
Signed-off-by: Lee Schermerhorn <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Yasunori Goto <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Rafael J. Wysocki <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: KAMEZAWA Hiroyuki <[email protected]>
Cc: Lee Schermerhorn <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Nishanth Aravamudan <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Adam Litke <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Cc: Eric Whitney <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>