The linux-next series "mm/memory_hotplug: Shrink zones before removing memory" [1] seems make a crash easier to reproduce while reading /proc/pagetypeinfo after offlining a memory section. Fix it by using pfn_to_online_page() in the PFN walker.
[1] https://lore.kernel.org/linux-mm/20191006085646.5768-1-da...@redhat.com/ page:ffffea0021200000 is uninitialized and poisoned raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p)) There is not page extension available. ------------[ cut here ]------------ kernel BUG at include/linux/mm.h:1107! RIP: 0010:pagetypeinfo_showmixedcount_print+0x4fb/0x680 Call Trace: walk_zones_in_node+0x3a/0xc0 pagetypeinfo_show+0x260/0x2c0 seq_read+0x27e/0x710 proc_reg_read+0x12e/0x190 __vfs_read+0x50/0xa0 vfs_read+0xcb/0x1e0 ksys_read+0xc6/0x160 __x64_sys_read+0x43/0x50 do_syscall_64+0xcc/0xaec entry_SYSCALL_64_after_hwframe+0x49/0xbe Signed-off-by: Qian Cai <c...@lca.pw> --- mm/page_owner.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index dee931184788..03a6b19b3cdd 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -296,11 +296,10 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m, pageblock_mt = get_pageblock_migratetype(page); for (; pfn < block_end_pfn; pfn++) { - if (!pfn_valid_within(pfn)) + page = pfn_to_online_page(pfn); + if (!page) continue; - page = pfn_to_page(pfn); - if (page_zone(page) != zone) continue; -- 1.8.3.1
