On Mon, Jan 25, 2021 at 10:05 AM Pingfan Liu <kernelfans@xxxxxxxxx> wrote:
>
> 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>
Applied as 5.11-rc material, thanks!
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