From: David Rientjes <[email protected]> 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 <[email protected]> Reviewed-by: Rik van Riel <[email protected]> Reviewed-by: Wanpeng Li <[email protected]> Acked-by: Mel Gorman <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> (cherry picked from commit f6ea3adb70b20ae36277a1b0eaaf4da9f6479a28) Signed-off-by: Andrey Ryabinin <[email protected]> --- mm/compaction.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index 63f5f4627ea7..f693bf3b87e2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -698,6 +698,13 @@ static void isolate_freepages(struct zone *zone, unsigned long isolated; unsigned long end_pfn; + /* + * 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; -- 2.13.6 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
