[PATCH v4 07/11] riscv: mm: Take memory hotplug read-lock during kernel page table dump

Björn Töpel
2024-06-05T11:41:48Z

During memory hot remove, the ptdump functionality can end up touching
stale data. Avoid any potential crashes (or worse), by holding the
memory hotplug read-lock while traversing the page table.

This change is analogous to arm64's commit bf2b59f60ee1 ("arm64/mm:
Hold memory hotplug lock while walking for kernel page table dump").

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
---
arch/riscv/mm/ptdump.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
index 1289cc6d3700..9d5f657a251b 100644
--- a/arch/riscv/mm/ptdump.c
+++ b/arch/riscv/mm/ptdump.c
@@ -6,6 +6,7 @@
#include <linux/efi.h>
#include <linux/init.h>
#include <linux/debugfs.h>
+#include <linux/memory_hotplug.h>
#include <linux/seq_file.h>
#include <linux/ptdump.h>

@@ -370,7 +371,9 @@ bool ptdump_check_wx(void)

static int ptdump_show(struct seq_file *m, void *v)
{
+ get_online_mems();
ptdump_walk(m, m->private);
+ put_online_mems();

return 0;
}
--
2.43.0