Skip to content

Commit

Permalink
mm/huge_memory: use pfn_to_online_page() in split_huge_pages_all()
Browse files Browse the repository at this point in the history 
NULL pointer dereference is triggered when calling thp split via debugfs
on the system with offlined memory blocks.  With debug option enabled, the
following kernel messages are printed out:

  page:00000000467f4890 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x121c000
  flags: 0x17fffc00000000(node=0|zone=2|lastcpupid=0x1ffff)
  raw: 0017fffc00000000 0000000000000000 dead000000000122 0000000000000000
  raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
  page dumped because: unmovable page
  page:000000007d7ab72e is uninitialized and poisoned
  page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
  ------------[ cut here ]------------
  kernel BUG at include/linux/mm.h:1248!
  invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 16 PID: 20964 Comm: bash Tainted: G          I        6.0.0-rc3-foll-numa+ ayufan-rock64#41
  ...
  RIP: 0010:split_huge_pages_write+0xcf4/0xe30

This shows that page_to_nid() in page_zone() is unexpectedly called for an
offlined memmap.

Use pfn_to_online_page() to get struct page in PFN walker.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: f1dd2cd ("mm, memory_hotplug: do not associate hotadded memory to zones until online")      [visible after d0dc12e]
Signed-off-by: Naoya Horiguchi <[email protected]>
Co-developed-by: David Hildenbrand <[email protected]>
Signed-off-by: David Hildenbrand <[email protected]>
Reviewed-by: Yang Shi <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Miaohe Lin <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Acked-by: Kirill A. Shutemov <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Muchun Song <[email protected]>
Cc: <[email protected]>	[5.10+]
Signed-off-by: Andrew Morton <[email protected]>
  • Loading branch information
@nhoriguchi @akpm00
nhoriguchi authored and akpm00 committed Sep 26, 2022
1 parent 58d426a commit 2b7aa91
Showing 1 changed file with 2 additions and 4 deletions.
6 changes: 2 additions & 4 deletions mm/huge_memory.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2894,11 +2894,9 @@ static void split_huge_pages_all(void)
max_zone_pfn = zone_end_pfn(zone);
for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
int nr_pages;
if (!pfn_valid(pfn))
continue;

page = pfn_to_page(pfn);
if (!get_page_unless_zero(page))
page = pfn_to_online_page(pfn);
if (!page || !get_page_unless_zero(page))
continue;

if (zone != page_zone(page))
Expand Down

0 comments on commit 2b7aa91

Please sign in to comment.