mm/compaction.c: periodically schedule when freeing pages

We've been getting warnings about an excessive amount of time spent allocating pages for migration during memory compaction without scheduling. isolate_freepages_block() already periodically checks for contended locks or the need to schedule, but isolate_freepages() never does. When a zone is massively long and no suitable targets can be found, this iteration can be quite expensive without ever doing cond_resched(). Check periodically for the need to reschedule while the compaction free scanner iterates. Signed-off-by: David Rientjes <rientjes@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/compaction.c: periodically schedule when freeing pages
We've been getting warnings about an excessive amount of time spent allocating pages for migration during memory compaction without scheduling. isolate_freepages_block() already periodically checks for contended locks or the need to schedule, but isolate_freepages() never does. When a zone is massively long and no suitable targets can be found, this iteration can be quite expensive without ever doing cond_resched(). Check periodically for the need to reschedule while the compaction free scanner iterates. Signed-off-by: David Rientjes <rientjes@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David Rientjes · Linus Torvalds
1 parent 7202365696
Showing 1 changed file with 7 additions and 0 deletions Side-by-side Diff
mm/compaction.c
@@ -677,6 +677,13 @@
 					pfn -= pageblock_nr_pages) {
 		unsigned long isolated;
  
+		/*
+		 * This can iterate a massively long zone without finding any
+		 * suitable migration targets, so periodically check if we need
+		 * to schedule.
+		 */
+		cond_resched();
+
 		if (!pfn_valid(pfn))
 			continue;
...	...	@@ -677,6 +677,13 @@
677	677	pfn -= pageblock_nr_pages) {
678	678	unsigned long isolated;
679	679
	680	+ /*
	681	+ * This can iterate a massively long zone without finding any
	682	+ * suitable migration targets, so periodically check if we need
	683	+ * to schedule.
	684	+ */
	685	+ cond_resched();
	686	+
680	687	if (!pfn_valid(pfn))
681	688	continue;
682	689