On Sun, Dec 01, 2024 at 11:09:10AM +0100, Magnus Lindholm wrote: > On Sun, Dec 1, 2024 at 5:31 AM Paul E. McKenney <paulmck@xxxxxxxxxx> wrote: > > > Does booting with the "rcupdate.rcu_normal=1" kernel boot parameter > > also suppress the problem? > > setting rcupdate.rcu_normal=1 also suppresses the problem. I guess this makes > RCU code not do synchronize_rcu_normal() in stead of the full > synchronize_rcu_expedited() which is where I get the kernel Oops. Exactly, though the effect is that any call to synchronize_rcu_expedited() instead results in a call to synchronize_rcu(). Which means that you can work around this problem without having to carry patches and without having to slow down network configuration for everyone else. ;-) > > That "pc =" down below is the program counter? If so, I am at a loss > > as to what RCU could do to make it be zero. > > No sure why this happens, if the RCU code is passing around pointers to > worker function and this somehow ends up being a null pointer on the Alpha? Are frame pointers enabled on your setup? If not, could you please enable them and reproduce the problem? Could you also please try building and reproducing with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y? Thanx, Paul
