2.6.38-stable review patch. If anyone has any objections, please let us know.
------------------ sleeping_prematurely From: Johannes Weiner <[email protected]> commit afc7e326a3f5bafc41324d7926c324414e343ee5 upstream. There are a few reports of people experiencing hangs when copying large amounts of data with kswapd using a large amount of CPU which appear to be due to recent reclaim changes. SLUB using high orders is the trigger but not the root cause as SLUB has been using high orders for a while. The root cause was bugs introduced into reclaim which are addressed by the following two patches. Patch 1 corrects logic introduced by commit 1741c877 ("mm: kswapd: keep kswapd awake for high-order allocations until a percentage of the node is balanced") to allow kswapd to go to sleep when balanced for high orders. Patch 2 notes that it is possible for kswapd to miss every cond_resched() and updates shrink_slab() so it'll at least reach that scheduling point. Chris Wood reports that these two patches in isolation are sufficient to prevent the system hanging. AFAIK, they should also resolve similar hangs experienced by James Bottomley. This patch: Johannes Weiner poined out that the logic in commit 1741c877 ("mm: kswapd: keep kswapd awake for high-order allocations until a percentage of the node is balanced") is backwards. Instead of allowing kswapd to go to sleep when balancing for high order allocations, it keeps it kswapd running uselessly. Signed-off-by: Mel Gorman <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Signed-off-by: Johannes Weiner <[email protected]> Reviewed-by: Wu Fengguang <[email protected]> Cc: James Bottomley <[email protected]> Tested-by: Colin King <[email protected]> Cc: Raghavendra D Prabhu <[email protected]> Cc: Jan Kara <[email protected]> Cc: Chris Mason <[email protected]> Cc: Christoph Lameter <[email protected]> Cc: Pekka Enberg <[email protected]> Cc: Rik van Riel <[email protected]> Reviewed-by: Minchan Kim <[email protected]> Reviewed-by: Wu Fengguang <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/vmscan.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2286,7 +2286,7 @@ static bool sleeping_prematurely(pg_data * must be balanced */ if (order) - return pgdat_balanced(pgdat, balanced, classzone_idx); + return !pgdat_balanced(pgdat, balanced, classzone_idx); else return !all_zones_ok; } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
