On Thu, Feb 15, 2018 at 01:02:27PM +0100, Ulrich Hecht wrote: > When the TTY buffers fill up to the configured maximum, a system lockup > occurs: > > [ 598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks: > [ 598.825796] 0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1 > [ 598.832577] (detected by 3, t=62517 jiffies, g=296, c=295, q=126) > [ 598.838755] Task dump for CPU 0: > [ 598.841977] swapper/0 R running task 0 0 0 0x00000022 > [ 598.849023] Call trace: > [ 598.851476] __switch_to+0x98/0xb0 > [ 598.854870] (null) > > This can be prevented by doing a dummy read of the RX data register. > > This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0; > reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms > as well. > > Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> > Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@xxxxxxxxx> Should this go to older kernel versions as well? If so, how far back? thanks, greg k-h
