On 17.02.21 17:36, Minchan Kim wrote:
alloc_contig_range is usually used on cma area or movable zone.
It's critical if the page migration fails on those areas so
dump more debugging message like memory_hotplug unless user
specifiy __GFP_NOWARN.
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
mm/page_alloc.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0b55c9c95364..67f3ee3a1528 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8486,6 +8486,15 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
}
if (ret < 0) {
+ if (!(cc->gfp_mask & __GFP_NOWARN)) {
+ struct page *page;
+
+ list_for_each_entry(page, &cc->migratepages, lru) {
+ pr_warn("migrating pfn %lx failed ret:%d ",
+ page_to_pfn(page), ret);
+ dump_page(page, "migration failure");
+ }
This can create *a lot* of noise. For example, until huge pages are
actually considered, we will choke on each end every huge page - and
might do so over and over again.
This might be helpful for debugging, but is unacceptable for production
systems for now I think. Maybe for now, do it based on CONFIG_DEBUG_VM.
+ }
putback_movable_pages(&cc->migratepages);
return ret;
}
@@ -8728,6 +8737,8 @@ struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
pfn = ALIGN(zone->zone_start_pfn, nr_pages);
while (zone_spans_last_pfn(zone, pfn, nr_pages)) {
if (pfn_range_valid_contig(zone, pfn, nr_pages)) {
+ unsigned long gfp_flags;
+
/*
* We release the zone lock here because
* alloc_contig_range() will also lock the zone
@@ -8736,8 +8747,11 @@ struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
* and cause alloc_contig_range() to fail...
*/
spin_unlock_irqrestore(&zone->lock, flags);
+
+ if (zone_idx(zone) != ZONE_MOVABLE)
+ gfp_flags = gfp_mask | __GFP_NOWARN;
This feels wrong. It might be better to make that decision inside
__alloc_contig_migrate_range() based on cc->zone.
--
Thanks,
David / dhildenb
