| Message ID | 20201030183809.3616803-2-zi.yan@sent.com |
|---|---|
| State | New |
| Headers | show |
| Series | None | expand |
On 10/30/20 7:38 PM, Zi Yan wrote: > From: Zi Yan <ziy@nvidia.com> > > In isolate_migratepages_block, if we have too many isolated pages and > nr_migratepages is not zero, we should try to migrate what we have > without wasting time on isolating. As you CC stable, there should be a stronger reason (strictly speaking the problem should have been observed in practice, but this is a simple patch, so they could accept it), so I suggest Andrew adds the following paragraph: In theory it's possible that multiple parallel compactions will cause too_many_isolated() to become true even if each has isolated less than COMPACT_CLUSTER_MAX, and loop forever in the while loop. Bailing immediately prevents that. > Fixes: 1da2f328fa64 (“mm,thp,compaction,cma: allow THP migration for CMA allocations”) > Suggested-by: Vlastimil Babka <vbabka@suse.cz> > Signed-off-by: Zi Yan <ziy@nvidia.com> > Cc: <stable@vger.kernel.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/compaction.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 3e834ac402f1..4d237a7c3830 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -817,6 +817,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, > * delay for some time until fewer pages are isolated > */ > while (unlikely(too_many_isolated(pgdat))) { > + /* stop isolation if there are still pages not migrated */ > + if (cc->nr_migratepages) > + return 0; > + > /* async migration should just abort */ > if (cc->mode == MIGRATE_ASYNC) > return 0; >
diff --git a/mm/compaction.c b/mm/compaction.c index 3e834ac402f1..4d237a7c3830 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -817,6 +817,10 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn, * delay for some time until fewer pages are isolated */ while (unlikely(too_many_isolated(pgdat))) { + /* stop isolation if there are still pages not migrated */ + if (cc->nr_migratepages) + return 0; + /* async migration should just abort */ if (cc->mode == MIGRATE_ASYNC) return 0;