Re: [PATCH v2 5/8] riscv: mm: Take memory hotplug read-lock during kernel page table dump

[David Hildenbrand]

On 14.05.24 16:04, Björn Töpel wrote:

From: Björn Töpel <bj...@rivosinc.com>

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").

Signed-off-by: Björn Töpel <bj...@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;

  }

Reviewed-by: David Hildenbrand <da...@redhat.com>

--
Cheers,

David / dhildenb