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path: root/drivers/misc/cxl/fault.c
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Diffstat (limited to 'drivers/misc/cxl/fault.c')
-rw-r--r--drivers/misc/cxl/fault.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
index 6eed7d03e2b5..f17f72ea0545 100644
--- a/drivers/misc/cxl/fault.c
+++ b/drivers/misc/cxl/fault.c
@@ -138,6 +138,22 @@ int cxl_handle_mm_fault(struct mm_struct *mm, u64 dsisr, u64 dar)
int result;
unsigned long access, flags, inv_flags = 0;
+ /*
+ * 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. This function get called with a
+ * valid mm for user space addresses. Hence using the if (mm)
+ * check is sufficient here.
+ */
+ 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;