On 9/2/20 3:49 AM, Vlastimil Babka wrote: > On 9/1/20 3:46 AM, Wei Yang wrote: >> The page allocated from buddy is not on any list, so just use list_add() >> is enough. >> >> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxxxxxxxxxx> >> Reviewed-by: Baoquan He <bhe@xxxxxxxxxx> >> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> >> --- >> mm/hugetlb.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/hugetlb.c b/mm/hugetlb.c >> index 441b7f7c623e..c9b292e664c4 100644 >> --- a/mm/hugetlb.c >> +++ b/mm/hugetlb.c >> @@ -2405,7 +2405,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma, >> h->resv_huge_pages--; >> } >> spin_lock(&hugetlb_lock); >> - list_move(&page->lru, &h->hugepage_activelist); >> + list_add(&page->lru, &h->hugepage_activelist); > > Hmm, how does that list_move() actually not crash today? > Page has been taken from free lists, thus there was list_del() and page->lru > should be poisoned. > list_move() does __list_del_entry() which will either detect the poison with > CONFIG_DEBUG_LIST, or crash accessing the poison, no? > Am I missing something or does it mean this code is actually never executed in wild? > There is not enough context in the diff, but the hugetlb page was not taken from the free list. Rather, it was just created by a call to alloc_buddy_huge_page_with_mpol(). As part of the allocation/creation prep_new_huge_page will be called which will INIT_LIST_HEAD(&page->lru). -- Mike Kravetz
