On 7/9/20 10:21 PM, Matthew Wilcox (Oracle) wrote:
> If we can't call page_mapping() to get the page mapping, handle the
> anon/ksm/movable bits correctly.
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
John's updated comment looks fine too.
> ---
> mm/debug.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/mm/debug.c b/mm/debug.c
> index 4f376514744d..e5de63406b59 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -70,7 +70,12 @@ void __dump_page(struct page *page, const char *reason)
>
> if (page < head || (page >= head + MAX_ORDER_NR_PAGES)) {
> /* Corrupt page, cannot call page_mapping */
> - mapping = page->mapping;
> + unsigned long tmp = (unsigned long)page->mapping;
> +
> + if (tmp & PAGE_MAPPING_ANON)
> + mapping = NULL;
> + else
> + mapping = (void *)(tmp & ~PAGE_MAPPING_FLAGS);
> head = page;
> compound = false;
> } else {
>
