diff options
| author | Mike Kravetz | 2021-02-24 12:07:50 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2021-02-24 13:38:33 -0800 |
| commit | dbfee5aee7e54f83d96ceb8e3e80717fac62ad63 (patch) | |
| tree | ac932854d5876873e6e1613dceeddfb588f13a5d | |
| parent | aca78307bfdaf3f99e040616f41aab7f8a566dfc (diff) | |
hugetlb: fix update_and_free_page contig page struct assumption
page structs are not guaranteed to be contiguous for gigantic pages. The
routine update_and_free_page can encounter a gigantic page, yet it assumes
page structs are contiguous when setting page flags in subpages.
If update_and_free_page encounters non-contiguous page structs, we can see
“BUG: Bad page state in process …” errors.
Non-contiguous page structs are generally not an issue. However, they can
exist with a specific kernel configuration and hotplug operations. For
example: Configure the kernel with CONFIG_SPARSEMEM and
!CONFIG_SPARSEMEM_VMEMMAP. Then, hotplug add memory for the area where
the gigantic page will be allocated. Zi Yan outlined steps to reproduce
here [1].
[1] https://lore.kernel.org/linux-mm/16F7C58B-4D79-41C5-9B64-A1A1628F4AF2@nvidia.com/
Link: https://lkml.kernel.org/r/20210217184926.33567-1-mike.kravetz@oracle.com
Fixes: 944d9fec8d7a ("hugetlb: add support for gigantic page allocation at runtime")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/hugetlb.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6786b313e6ac..3f6a50373d4f 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1321,14 +1321,16 @@ static inline void destroy_compound_gigantic_page(struct page *page, static void update_and_free_page(struct hstate *h, struct page *page) { int i; + struct page *subpage = page; if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported()) return; h->nr_huge_pages--; h->nr_huge_pages_node[page_to_nid(page)]--; - for (i = 0; i < pages_per_huge_page(h); i++) { - page[i].flags &= ~(1 << PG_locked | 1 << PG_error | + for (i = 0; i < pages_per_huge_page(h); + i++, subpage = mem_map_next(subpage, page, i)) { + subpage->flags &= ~(1 << PG_locked | 1 << PG_error | 1 << PG_referenced | 1 << PG_dirty | 1 << PG_active | 1 << PG_private | 1 << PG_writeback); |