From: Baoquan He bhe@redhat.com
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
--- kernel/kexec_core.c | 2 -- 1 file changed, 2 deletions(-)
--- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1135,7 +1135,6 @@ int kernel_kexec(void)
#ifdef CONFIG_KEXEC_JUMP if (kexec_image->preserve_context) { - lock_system_sleep(); pm_prepare_console(); error = freeze_processes(); if (error) { @@ -1198,7 +1197,6 @@ int kernel_kexec(void) thaw_processes(); Restore_console: pm_restore_console(); - unlock_system_sleep(); } #endif