[127/181] mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()

Commit Message

Andrew Morton Oct. 13, 2020, 11:55 p.m. UTC

From: David Hildenbrand <[e-mail]>
Subject: mm/page_isolation: drop WARN_ON_ONCE() in set_migratetype_isolate()

Inside has_unmovable_pages(), we have a comment describing how unmovable
data could end up in ZONE_MOVABLE - via "movablecore".  Also, besides
checking if the first page in the pageblock is reserved, we don't perform
any further checks in case of ZONE_MOVABLE.

In case of memory offlining, we set REPORT_FAILURE, properly dump_page()
the page and handle the error gracefully.  alloc_contig_pages() users
currently never allocate from ZONE_MOVABLE.  E.g., hugetlb uses
alloc_contig_pages() for the allocation of gigantic pages only, which will
never end up on the MOVABLE zone (see htlb_alloc_mask()).

Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Reviewed-by: Baoquan He <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Michael S. Tsirkin <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Pankaj Gupta <[e-mail]>
Cc: Jason Wang <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Qian Cai <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/page_isolation.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

Patch

--- a/mm/page_isolation.c~mm-page_isolation-drop-warn_on_once-in-set_migratetype_isolate
+++ a/mm/page_isolation.c
@@ -57,15 +57,12 @@  static int set_migratetype_isolate(struc
 	spin_unlock_irqrestore(&zone->lock, flags);
 	if (!ret) {
 		drain_all_pages(zone);
-	} else {
-		WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE);
-
-		if ((isol_flags & REPORT_FAILURE) && unmovable)
-			/*
-			 * printk() with zone->lock held will likely trigger a
-			 * lockdep splat, so defer it here.
-			 */
-			dump_page(unmovable, "unmovable page");
+	} else if ((isol_flags & REPORT_FAILURE) && unmovable) {
+		/*
+		 * printk() with zone->lock held will likely trigger a
+		 * lockdep splat, so defer it here.
+		 */
+		dump_page(unmovable, "unmovable page");
 	}
 
 	return ret;