mm_cpumask trimming is currently restricted to be issued by the current
thread of a single-threaded mm. This patch relaxes that and allows the
mask to be trimmed from any context.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/mm/book3s64/radix_tlb.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c
b/arch/powerpc/mm/book3s64/radix_tlb.c
index 5b62e2e7371c..7b199bee4baa 100644
--- a/arch/powerpc/mm/book3s64/radix_tlb.c
+++ b/arch/powerpc/mm/book3s64/radix_tlb.c
@@ -657,20 +657,16 @@ static void do_exit_flush_lazy_tlb(void *arg)
}
/*
- * This IPI is only initiated from a CPU which is running mm which
- * is a single-threaded process, so there will not be another racing
- * IPI coming in where we would find our cpumask already clear.
- *
- * Nothing else clears our bit in the cpumask except CPU offlining,
- * in which case we should not be taking IPIs here. However check
- * this just in case the logic is wrong somewhere, and don't underflow
- * the active_cpus count.
+ * This IPI may be initiated from any source including those not
+ * running the mm, so there may be a racing IPI that comes after
+ * this one which finds the cpumask already clear. Check and avoid
+ * underflowing the active_cpus count in that case. The race should
+ * not otherwise be a problem, but the TLB must be flushed because
+ * that's what the caller expects.
*/
if (cpumask_test_cpu(cpu, mm_cpumask(mm))) {
atomic_dec(&mm->context.active_cpus);
cpumask_clear_cpu(cpu, mm_cpumask(mm));
- } else {
- WARN_ON_ONCE(1);
}
out_flush:
--
2.23.0
