In the Linux kernel, the following vulnerability has been resolved: mm: memcg: fix NULL pointer in memcgrouptrackforeigndirtyslowpath() As commit 18365225f044 ("hwpoison, memcg: forcibly uncharge LRU pages"), hwpoison will forcibly uncharg a LRU hwpoisoned page, the foliomemcg could be NULl, then, memcgrouptrackforeigndirtyslowpath() could occurs a NULL pointer dereference, let's do not record the foreign writebacks for folio memcg is null in memcgrouptrackforeign_dirty() to fix it.