[PATCH for v4.9 LTS 85/87] mm: don't dereference struct page fields of invalid pages

From: Ard Biesheuvel [ Upstream commit f073bdc51771f5a5c7a8d1191bfc3ae371d44de7 ] The VM_BUG_ON() check in move_freepages() checks whether the node id of a page matches the node id of its zone. However, it does this before having checked whether the struct page

[PATCH for v4.9 LTS 85/87] mm: don't dereference struct page fields of invalid pages

From: Ard Biesheuvel [ Upstream commit f073bdc51771f5a5c7a8d1191bfc3ae371d44de7 ] The VM_BUG_ON() check in move_freepages() checks whether the node id of a page matches the node id of its zone. However, it does this before having checked whether the struct page pointer refers to a valid struct