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 <minc...@kernel.org>
---
 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");
+                       }
+               }
                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;
                                ret = __alloc_contig_pages(pfn, nr_pages,
-                                                       gfp_mask);
+                                                       gfp_flags);
                                if (!ret)
                                        return pfn_to_page(pfn);
                                spin_lock_irqsave(&zone->lock, flags);
-- 
2.30.0.478.g8a0d178c01-goog

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