FAILED: patch "[PATCH] mm/huge_memory: use pfn_to_online_page() in" failed to apply to 5.10-stable tree

The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

2b7aa91ba0e8 ("mm/huge_memory: use pfn_to_online_page() in split_huge_pages_all()") a17206dac7b2 ("mm/huge_memory: minor cleanup for split_huge_pages_all") fa6c02315f74 ("mm: huge_memory: a new debugfs interface for splitting THP tests") f3a45709d2bb ("selftests/vm: hmm-tests: remove the libhugetlbfs dependency") f545605cc08e ("selftests/vm: minor cleanup: Makefile and gup_test.c") b9dcfdff8b4b ("selftests/vm: use a common gup_test.h")
9c84f229268f ("mm/gup_benchmark: rename to mm/gup_test")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2b7aa91ba0e86b8643f5d3c83874c80599c731d7 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <[email protected]>
Date: Thu, 8 Sep 2022 13:11:50 +0900
Subject: [PATCH] mm/huge_memory: use pfn_to_online_page() in
split_huge_pages_all()

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+ #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.

index e9414ee57c5b..f42bb51e023a 100644
@@ -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))