kernel: kexec: remove the lock operation of system_transition_mutex

Function kernel_kexec() is called with lock system_transition_mutex
held in reboot system call. While inside kernel_kexec(), it will
acquire system_transition_mutex agin. This will lead to dead lock.

The dead lock should be easily triggered, it hasn't caused any
failure report just because the feature 'kexec jump' is almost not
used by anyone as far as I know. An inquiry can be made about who
is using 'kexec jump' and where it's used. Before that, let's simply
remove the lock operation inside CONFIG_KEXEC_JUMP ifdeffery scope.

Fixes: 55f2503c3b69 ("PM / reboot: Eliminate race between reboot and suspend")
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Pingfan Liu <kernelfans@gmail.com>
Cc: 4.19+ <stable@vger.kernel.org> # 4.19+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 4f8efc278aa75bc22fc4387e11fe6b8d48548135..aa919585c24b4adb914433fcfdd06999b3a212e6 100644 (file)
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1134,7 +1134,6 @@ int kernel_kexec(void)
 
 #ifdef CONFIG_KEXEC_JUMP
        if (kexec_image->preserve_context) {
-               lock_system_sleep();
                pm_prepare_console();
                error = freeze_processes();
                if (error) {
@@ -1197,7 +1196,6 @@ int kernel_kexec(void)
                thaw_processes();
  Restore_console:
                pm_restore_console();
-               unlock_system_sleep();
        }
 #endif