migrate_pages() can return positive value while at the same time emptying the list of pages it was called with. Such situation means that it went through all the pages on the list some of which failed to be migrated.
If that happens, __alloc_contig_migrate_range()'s loop may finish without "++tries == 5" never being checked. This in turn means that at the end of the function, ret may have a positive value, which should be treated as an error. This patch changes __alloc_contig_migrate_range() so that the return statement converts positive ret value into -EBUSY error. Signed-off-by: Joonsoo Kim <[email protected]> Cc: Michal Nazarewicz <[email protected]> Cc: Marek Szyprowski <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Christoph Lameter <[email protected]> Acked-by: Christoph Lameter <[email protected]> Acked-by: Michal Nazarewicz <[email protected]> diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 4403009..02d4519 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5673,7 +5673,6 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end) } tries = 0; } else if (++tries == 5) { - ret = ret < 0 ? ret : -EBUSY; break; } @@ -5683,7 +5682,7 @@ static int __alloc_contig_migrate_range(unsigned long start, unsigned long end) } putback_lru_pages(&cc.migratepages); - return ret > 0 ? 0 : ret; + return ret <= 0 ? ret : -EBUSY; } /* -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
