On (23/03/23 17:18), Sebastian Andrzej Siewior wrote: > From: Mike Galbraith <umgwanakikbuti@xxxxxxxxx> > > The bit spinlock disables preemption. The spinlock_t lock becomes a sleeping > lock on PREEMPT_RT and it can not be acquired in this context. In this locked > section, zs_free() acquires a zs_pool::lock, and there is access to > zram::wb_limit_lock. > > Use a spinlock_t on PREEMPT_RT for locking and set/ clear ZRAM_LOCK bit after > the lock has been acquired/ dropped. > > Signed-off-by: Mike Galbraith <umgwanakikbuti@xxxxxxxxx> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> > Link: https://lkml.kernel.org/r/YqIbMuHCPiQk+Ac2@xxxxxxxxxxxxx > --- > > I'm simply forwarding Mike's patch here. The other alternative is to let > the driver depend on !PREEMPT_RT. I can't tell likely it is that this > driver is used. Mike most likely stumbled upon it while running LTP. Yeah, I'm curious if anyone uses zram in preempt-rt systems. I don't mind this patch but would be nice to add new code when it solves some real problems. Maybe `depend on !PREEMPT_RT` can be a better option.
