FAILED: patch "[PATCH] mm/huge_memory: use pfn_to_online_page() in" failed to apply to 5.15-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.15-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 <stable@vger.kernel.org>.

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")

thanks,

greg k-h

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

From 2b7aa91ba0e86b8643f5d3c83874c80599c731d7 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <naoya.horiguchi@nec.com>
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.

Link: https://lkml.kernel.org/r/20220908041150.3430269-1-naoya.horiguchi@linux.dev
Fixes: f1dd2cd13c4b ("mm, memory_hotplug: do not associate hotadded memory to zones until online")      [visible after d0dc12e86b319]
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Co-developed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: <stable@vger.kernel.org>	[5.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index e9414ee57c5b..f42bb51e023a 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -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))