On Fri, Jan 22, 2021 at 3:42 PM Baoquan He <bhe@xxxxxxxxxx> wrote:
>
> 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.
>
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Reviewed-by: Pingfan Liu <kernelfans@xxxxxxxxx>
> ---
> kernel/kexec_core.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 80905e5aa8ae..a0b6780740c8 100644
> --- 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
>
> --
> 2.17.2
>
Reviewed-by: Pingfan Liu <kernelfans@xxxxxxxxx>
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