@@ -960,30 +960,43 @@ static int __get_hwpoison_page(struct pa
{
struct page *head = compound_head(page);
- if (!PageHuge(head) && PageTransHuge(head)) {
- /*
- * Non anonymous thp exists only in allocation/free time. We
- * can't handle such a case correctly, so let's give it up.
- * This should be better than triggering BUG_ON when kernel
- * tries to touch the "partially handled" page.
- */
- if (!PageAnon(head)) {
- pr_err("Memory failure: %#lx: non anonymous thp\n",
- page_to_pfn(page));
- return 0;
- }
- }
+ if (PageCompound(page)) {
+ if (PageSlab(page)) {
+ return get_page_unless_zero(page);
+ } else if (PageHuge(head)) {
+ int ret = 0;
- if (get_page_unless_zero(head)) {
- if (head == compound_head(page))
- return 1;
-
- pr_info("Memory failure: %#lx cannot catch tail\n",
- page_to_pfn(page));
- put_page(head);
+ spin_lock(&hugetlb_lock);
+ if (!PageHuge(head))
+ ret = -EBUSY;
+ else if (HPageFreed(head) || HPageMigratable(head))
+ ret = get_page_unless_zero(head);
+ spin_unlock(&hugetlb_lock);
+ return ret;
+ } else if (PageTransHuge(head)) {
+ /*
+ * Non anonymous thp exists only in allocation/free time. We
+ * can't handle such a case correctly, so let's give it up.
+ * This should be better than triggering BUG_ON when kernel
+ * tries to touch the "partially handled" page.
+ */
+ if (!PageAnon(head)) {
+ pr_err("Memory failure: %#lx: non anonymous thp\n",
+ page_to_pfn(page));
+ return 0;
+ }
+ if (get_page_unless_zero(head)) {
+ if (head == compound_head(page))
+ return 1;
+ pr_info("Memory failure: %#lx cannot catch tail\n",
+ page_to_pfn(page));
+ put_page(head);
+ }
+ }
+ return 0;
}
- return 0;
+ return get_page_unless_zero(page);
}
/*
The patch titled Subject: mm,hwpoison: fix race with compound page allocation has been added to the -mm tree. Its filename is mmhwpoison-fix-race-with-compound-page-allocation.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mmhwpoison-fix-race-with-compound-page-allocation.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mmhwpoison-fix-race-with-compound-page-allocation.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Naoya Horiguchi <naoya.horiguchi@nec.com> Subject: mm,hwpoison: fix race with compound page allocation When hugetlb page fault (under overcommiting situation) and memory_failure() race, VM_BUG_ON_PAGE() is triggered by the following race: CPU0: CPU1: gather_surplus_pages() page = alloc_surplus_huge_page() memory_failure_hugetlb() get_hwpoison_page(page) __get_hwpoison_page(page) get_page_unless_zero(page) zero = put_page_testzero(page) VM_BUG_ON_PAGE(!zero, page) enqueue_huge_page(h, page) put_page(page) __get_hwpoison_page() only checks page refcount before taking additional one for memory error handling, which is wrong because there's time windows where compound pages have non-zero refcount during initialization. So make __get_hwpoison_page() check page status a bit more for a few types of compound pages. PageSlab() check is added because otherwise "non anonymous thp" path is wrongly chosen. Link: https://lkml.kernel.org/r/20210511151016.2310627-2-nao.horiguchi@gmail.com Fixes: ead07f6a867b ("mm/memory-failure: introduce get_hwpoison_page() for consistent refcount handling") Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reported-by: Muchun Song <songmuchun@bytedance.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Tony Luck <tony.luck@intel.com> Cc: <stable@vger.kernel.org> [5.12+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/memory-failure.c | 55 +++++++++++++++++++++++++----------------- 1 file changed, 34 insertions(+), 21 deletions(-)