Below kernel vm bug can be triggered by tcpdump which mmaped a lot of pages with GFP_COMP flag. [Mon May 25 05:29:33 2015] page:ffffea0015414000 count:66 mapcount:1 mapping: (null) index:0x0 [Mon May 25 05:29:33 2015] flags: 0x20047580004000(head) [Mon May 25 05:29:33 2015] page dumped because: VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page)) [Mon May 25 05:29:33 2015] ------------[ cut here ]------------ [Mon May 25 05:29:33 2015] kernel BUG at mm/migrate.c:1661! [Mon May 25 05:29:33 2015] invalid opcode: 0000 [#1] SMP The fix is simply disallow migrate mmaped compound pages, return 0 instead of report vm bug. Signed-off-by: Jovi Zhangwei --- mm/migrate.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/migrate.c b/mm/migrate.c index f53838f..839adef 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1606,7 +1606,8 @@ static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) { int page_lru; - VM_BUG_ON_PAGE(compound_order(page) && !PageTransHuge(page), page); + if (compound_order(page) && !PageTransHuge(page)) + return 0; /* Avoid migrating to a node that is nearly full */ if (!migrate_balanced_pgdat(pgdat, 1UL << compound_order(page))) -- 1.9.1