1 files changed, 6 insertions, 3 deletions

diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index b7b397802088..efcf1f7ef1e4 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -179,7 +179,7 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
                                                  &asid_generation);
         flush_context(cpu);
 
-        /* We have at least 1 ASID per CPU, so this will always succeed */
+        /* We have more ASIDs than CPUs, so this will always succeed */
         asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1);
 
 set_asid:
@@ -227,8 +227,11 @@ switch_mm_fastpath:
 static int asids_init(void)
 {
         asid_bits = get_cpu_asid_bits();
-        /* If we end up with more CPUs than ASIDs, expect things to crash */
-        WARN_ON(NUM_USER_ASIDS < num_possible_cpus());
+        /*
+         * Expect allocation after rollover to fail if we don't have at least
+         * one more ASID than CPUs. ASID #0 is reserved for init_mm.
+         */
+        WARN_ON(NUM_USER_ASIDS - 1 <= num_possible_cpus());
         atomic64_set(&asid_generation, ASID_FIRST_VERSION);
         asid_map = kzalloc(BITS_TO_LONGS(NUM_USER_ASIDS) * sizeof(*asid_map),
                            GFP_KERNEL);