kernel: kexec: remove the lock operation of system_transition_mutex

commit 56c91a18432b631ca18438841fd1831ef756cabf upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index faeec8255e7e0e8563ee34f0ac04e0b4ca29489c..6b3d7f7211dd6a2f749b246caf1ebed433ecda8e 100644 (file)
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -1130,7 +1130,6 @@ int kernel_kexec(void)
 
 #ifdef CONFIG_KEXEC_JUMP
        if (kexec_image->preserve_context) {
-               lock_system_sleep();
                pm_prepare_console();
                error = freeze_processes();
                if (error) {
@@ -1193,7 +1192,6 @@ int kernel_kexec(void)
                thaw_processes();
  Restore_console:
                pm_restore_console();
-               unlock_system_sleep();
        }
 #endif