From 9aa5d5a606db453a7aa4426820a5cbd1330fc15c Mon Sep 17 00:00:00 2001 From: Mike Kravetz Date: Thu, 14 Apr 2022 19:13:52 -0700 Subject: [PATCH] hugetlb: do not demote poisoned hugetlb pages It is possible for poisoned hugetlb pages to reside on the free lists. The huge page allocation routines which dequeue entries from the free lists make a point of avoiding poisoned pages. There is no such check and avoidance in the demote code path. If a hugetlb page on the is on a free list, poison will only be set in the head page rather then the page with the actual error. If such a page is demoted, then the poison flag may follow the wrong page. A page without error could have poison set, and a page with poison could not have the flag set. Check for poison before attempting to demote a hugetlb page. Also, return -EBUSY to the caller if only poisoned pages are on the free list. Link: https://lkml.kernel.org/r/20220307215707.50916-1-mike.kravetz@oracle.com Fixes: 18cdd059edf6 ("hugetlb: add hugetlb demote page support") Signed-off-by: Mike Kravetz Reviewed-by: Naoya Horiguchi Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index b34f50156f7ec..f8ca7cca3c1ab 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -3475,7 +3475,6 @@ static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed) { int nr_nodes, node; struct page *page; - int rc = 0; lockdep_assert_held(&hugetlb_lock); @@ -3486,15 +3485,19 @@ static int demote_pool_huge_page(struct hstate *h, nodemask_t *nodes_allowed) } for_each_node_mask_to_free(h, nr_nodes, node, nodes_allowed) { - if (!list_empty(&h->hugepage_freelists[node])) { - page = list_entry(h->hugepage_freelists[node].next, - struct page, lru); - rc = demote_free_huge_page(h, page); - break; + list_for_each_entry(page, &h->hugepage_freelists[node], lru) { + if (PageHWPoison(page)) + continue; + + return demote_free_huge_page(h, page); } } - return rc; + /* + * Only way to get here is if all pages on free lists are poisoned. + * Return -EBUSY so that caller will not retry. + */ + return -EBUSY; } #define HSTATE_ATTR_RO(_name) \ -- 2.39.5