mm/page_alloc: remove the throttling logic from the page allocator

The page allocator stalls based on the number of pages that are waiting
for writeback to start but this should now be redundant.
shrink_inactive_list() will wake flusher threads if the LRU tail are
unqueued dirty pages so the flusher should be active.  If it fails to
make progress due to pages under writeback not being completed quickly
then it should stall on VMSCAN_THROTTLE_WRITEBACK.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: "Darrick J . Wong" <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: NeilBrown <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 20 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0f1f1f353211..0f74a66bed19 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4791,30 +4791,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order,
 		trace_reclaim_retry_zone(z, order, reclaimable,
 				available, min_wmark, *no_progress_loops, wmark);
 		if (wmark) {
-			/*
-			 * If we didn't make any progress and have a lot of
-			 * dirty + writeback pages then we should wait for
-			 * an IO to complete to slow down the reclaim and
-			 * prevent from pre mature OOM
-			 */
-			if (!did_some_progress) {
-				unsigned long write_pending;
-
-				write_pending = zone_page_state_snapshot(zone,
-							NR_ZONE_WRITE_PENDING);
-
-				if (2 * write_pending > reclaimable) {
-					congestion_wait(BLK_RW_ASYNC, HZ/10);
-					return true;
-				}
-			}
-
 			ret = true;
-			goto out;
+			break;
 		}
 	}
 
-out:
 	/*
 	 * Memory allocation/reclaim might be called from a WQ context and the
 	 * current implementation of the WQ concurrency control doesn't