The mmap_lock is held around tb_gen_code.  While the comment
is correct that the lock is dropped when tb_gen_code runs out
of memory, the lock is *not* dropped when an exception is
raised reading code for translation.

Acked-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/cpu-exec.c  | 12 ++++++------
 accel/tcg/user-exec.c |  3 ---
 2 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index a565a3f8ec..d18081ca6f 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -462,13 +462,11 @@ void cpu_exec_step_atomic(CPUState *cpu)
         cpu_tb_exec(cpu, tb, &tb_exit);
         cpu_exec_exit(cpu);
     } else {
-        /*
-         * The mmap_lock is dropped by tb_gen_code if it runs out of
-         * memory.
-         */
 #ifndef CONFIG_SOFTMMU
         clear_helper_retaddr();
-        tcg_debug_assert(!have_mmap_lock());
+        if (have_mmap_lock()) {
+            mmap_unlock();
+        }
 #endif
         if (qemu_mutex_iothread_locked()) {
             qemu_mutex_unlock_iothread();
@@ -936,7 +934,9 @@ int cpu_exec(CPUState *cpu)
 
 #ifndef CONFIG_SOFTMMU
         clear_helper_retaddr();
-        tcg_debug_assert(!have_mmap_lock());
+        if (have_mmap_lock()) {
+            mmap_unlock();
+        }
 #endif
         if (qemu_mutex_iothread_locked()) {
             qemu_mutex_unlock_iothread();
diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c
index 2bc4394b80..521aa8b61e 100644
--- a/accel/tcg/user-exec.c
+++ b/accel/tcg/user-exec.c
@@ -80,10 +80,7 @@ MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write)
          * (and if the translator doesn't handle page boundaries correctly
          * there's little we can do about that here).  Therefore, do not
          * trigger the unwinder.
-         *
-         * Like tb_gen_code, release the memory lock before cpu_loop_exit.
          */
-        mmap_unlock();
         *pc = 0;
         return MMU_INST_FETCH;
     }
-- 
2.34.1