linux-kernel - [PATCH] mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM

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Date:   Thu,  6 Feb 2020 20:53:43 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     akpm@...ux-foundation.org, osalvador@...e.de,
        dan.j.williams@...el.com
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org, david@...hat.com,
        bhe@...hat.com, Wei Yang <richardw.yang@...ux.intel.com>
Subject: [PATCH] mm/sparsemem: pfn_to_page is not valid yet on SPARSEMEM

When we use SPARSEMEM instead of SPARSEMEM_VMEMMAP, pfn_to_page()
doesn't work before sparse_init_one_section() is called. This leads to a
crash when hotplug memory.

We should use memmap as it did.

Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
CC: Dan Williams <dan.j.williams@...el.com>
---
 mm/sparse.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 5a8599041a2a..2efb24ff8f96 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -882,7 +882,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 	 * Poison uninitialized struct pages in order to catch invalid flags
 	 * combinations.
 	 */
-	page_init_poison(pfn_to_page(start_pfn), sizeof(struct page) * nr_pages);
+	page_init_poison(memmap, sizeof(struct page) * nr_pages);
 
 	ms = __nr_to_section(section_nr);
 	set_section_nid(section_nr, nid);
-- 
2.17.1