Reading /proc/kpageflags for pfns allocated by pmem namespace triggers
kernel panic with a message like "BUG: unable to handle kernel paging
request at fffffffffffffffe".
The first few pages (controlled by altmap passed to memmap_init_zone())
in the ZONE_DEVICE can skip struct page initialization, which causes
the reported issue.
This patch simply adds some initialization code for them.
Fixes: 4b94ffdc4163 ("x86, mm: introduce vmem_altmap to augment
vmemmap_populate()")
Signed-off-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
---
mm/page_alloc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git v4.17-mmotm-2018-06-07-16-59/mm/page_alloc.c
v4.17-mmotm-2018-06-07-16-59_patched/mm/page_alloc.c
index 1772513..0b36afe 100644
--- v4.17-mmotm-2018-06-07-16-59/mm/page_alloc.c
+++ v4.17-mmotm-2018-06-07-16-59_patched/mm/page_alloc.c
@@ -5574,8 +5574,16 @@ void __meminit memmap_init_zone(unsigned long size, int
nid, unsigned long zone,
* Honor reservation requested by the driver for this ZONE_DEVICE
* memory
*/
- if (altmap && start_pfn == altmap->base_pfn)
+ if (altmap && start_pfn == altmap->base_pfn) {
+ unsigned long i;
+
+ for (i = 0; i < altmap->reserve; i++) {
+ page = pfn_to_page(start_pfn + i);
+ __init_single_page(page, start_pfn + i, zone, nid);
+ SetPageReserved(page);
+ }
start_pfn += altmap->reserve;
+ }
for (pfn = start_pfn; pfn < end_pfn; pfn++) {
/*
--
2.7.0
