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-rw-r--r--arch/Kconfig15
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 643f8a04141e..205fd23e0cad 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -481,6 +481,21 @@ config ARCH_WANT_IRQS_OFF_ACTIVATE_MM
# converted already).
config MMU_LAZY_TLB_REFCOUNT
def_bool y
+ depends on !MMU_LAZY_TLB_SHOOTDOWN
+
+# This option allows MMU_LAZY_TLB_REFCOUNT=n. It ensures no CPUs are using an
+# mm as a lazy tlb beyond its last reference count, by shooting down these
+# users before the mm is deallocated. __mmdrop() first IPIs all CPUs that may
+# be using the mm as a lazy tlb, so that they may switch themselves to using
+# init_mm for their active mm. mm_cpumask(mm) is used to determine which CPUs
+# may be using mm as a lazy tlb mm.
+#
+# To implement this, an arch *must*:
+# - At the time of the final mmdrop of the mm, ensure mm_cpumask(mm) contains
+# at least all possible CPUs in which the mm is lazy.
+# - It must meet the requirements for MMU_LAZY_TLB_REFCOUNT=n (see above).
+config MMU_LAZY_TLB_SHOOTDOWN
+ bool
config ARCH_HAVE_NMI_SAFE_CMPXCHG
bool