Commit f6ea3adb authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds

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: default avatarDavid Rientjes <rientjes@google.com>
Reviewed-by: default avatarRik van Riel <riel@redhat.com>
Reviewed-by: default avatarWanpeng Li <liwanp@linux.vnet.ibm.com>
Acked-by: default avatarMel Gorman <mgorman@suse.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 72023656
......@@ -677,6 +677,13 @@ static void isolate_freepages(struct zone *zone,
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;
......
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