On 9/14/2022 1:49 PM, Andrew Morton wrote:
On Wed, 14 Sep 2022 12:09:17 -0700 Doug Berger <opendmb@xxxxxxxxx> wrote:
With gigantic pages it may not be true that struct page structures
are contiguous across the entire gigantic page. The nth_page macro
is used here in place of direct pointer arithmetic to correct for
this.
What were the user-visible runtime effects of this bug?
As Mike said this would only conceptually be a problem for systems with
CONFIG_SPARSEMEM && !CONFIG_SPARSEMEM_VMEMMAP, and could cause kernel
address exceptions or memory corruption with unpredictable side effects.
However, I am unaware of a system other than perhaps the PS3 that uses
the classic sparse addressing, so the odds of such a system also using
gigantic hugetlbfs pages that it wants to demote is likely quite small.
Thanks,
-Doug
