From: Björn Töpel bjorn@rivosinc.com
[ Upstream commit 37992b7f1097ba79ca75ba5a26ddcf0f54f91a08 ]
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 Link: https://lore.kernel.org/r/20240605114100.315918-8-bjorn@kernel.org Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 830e7de65e3a3..154cc427f4957 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>
@@ -351,7 +352,9 @@ void 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; }