diff options
| -rw-r--r-- | drivers/misc/cxl/fault.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c index ab507e4ed69b..f17f72ea0545 100644 --- a/drivers/misc/cxl/fault.c +++ b/drivers/misc/cxl/fault.c @@ -141,9 +141,19 @@ int cxl_handle_mm_fault(struct mm_struct *mm, u64 dsisr, u64 dar) /* * Add the fault handling cpu to task mm cpumask so that we * can do a safe lockless page table walk when inserting the - * hash page table entry. + * hash page table entry. This function get called with a + * valid mm for user space addresses. Hence using the if (mm) + * check is sufficient here. */ - cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); + if (mm && !cpumask_test_cpu(smp_processor_id(), mm_cpumask(mm))) { + cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); + /* + * We need to make sure we walk the table only after + * we update the cpumask. The other side of the barrier + * is explained in serialize_against_pte_lookup() + */ + smp_mb(); + } if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) { pr_devel("copro_handle_mm_fault failed: %#x\n", result); return result; |