mm/thp: do not wait for lock_page() in deferred_split_scan()

deferred_split_scan() gets called from reclaim path. Waiting for page lock may lead to deadlock there. Replace lock_page() with trylock_page() and skip the page if we failed to lock it. We will get to the page on the next scan. Link: http://lkml.kernel.org/r/[email protected] Fixes: 9a98225 ("thp: introduce deferred_split_huge_page()") Signed-off-by: Kirill A. Shutemov <[email protected]> Acked-by: Michal Hocko <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
josf · Mar 23, 2018 · fa41b90 · fa41b90
1 parent fece202
commit fa41b90
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
@@ -2783,11 +2783,13 @@ static unsigned long deferred_split_scan(struct shrinker *shrink,
 
 	list_for_each_safe(pos, next, &list) {
 		page = list_entry((void *)pos, struct page, mapping);
-		lock_page(page);
+		if (!trylock_page(page))
+			goto next;
 		/* split_huge_page() removes page from list on success */
 		if (!split_huge_page(page))
 			split++;
 		unlock_page(page);
+next:
 		put_page(page);
 	}