On 23/01/2020 21.39, Steven Rostedt wrote: > 4.19.94-rt39-rc2 stable review patch. > If anyone has any objections, please let me know. > > ------------------ > > From: Julien Grall <julien.grall@xxxxxxx> > > [ Upstream commit cef1b87f98823af923a386f3f69149acb212d4a1 ] > > As tglx puts it: > |If base == migration_base then there is no point to lock soft_expiry_lock > |simply because the timer is not executing the callback in soft irq context > |and the whole lock/unlock dance can be avoided. > > Furthermore, all the path leading to hrtimer_grab_expiry_lock() assumes > timer->base and timer->base->cpu_base are always non-NULL. So it is safe > to remove the NULL checks here. > > Signed-off-by: Julien Grall <julien.grall@xxxxxxx> > Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1908211557420.2223@xxxxxxxxxxxxxxxxxxxxxxx > Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx> > [bigeasy: rewrite changelog] > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Pretty late to the party, but I think I've bisected a problem to this patch (and its required fixup for !SMP, "hrtimer: Add a missing bracket and hide `migration_base on !SMP"). Originally, a customer reported that upgrading from 4.19.82-rt30 to v4.19.106-rt45 failed to boot, stalling around the time the network gets initialized (this is a board with an embedded Marvell switch). Perhaps 1 in 10 times, the board would come up successfully. I haven't been able to reproduce that particular problem (or, perhaps I've seen it once or twice, but not nearly often enough to use that as a basis for bisection). However, building with their rescue initrd and booting that, the board would consistently hang during reboot. Sometimes I would get lines like [ 72.956630] sched: RT throttling activated [ 72.973769] lanx: port 1(lan1) entered disabled state [ 73.000401] lanx: port 2(lan2) entered disabled state [ 73.974951] lanx: port 3(lan3) entered disabled state [ 73.997473] lanx: port 4(lan4) entered disabled state [ 74.968006] lanx: port 5(lan5) entered disabled state other times there would be no output, but the board was still hanging. Reverting b1a471ec4df1 - hrtimer: Prevent using hrtimer_grab_expiry_lock() on migration_base 40aae5708e7a - hrtimer: Add a missing bracket and hide `migration_base' on !SMP on top of v4.19.94-rt39 makes that problem go away, i.e. the board reboots as expected. The board is a 32 bit powerpc (mpc8309) !SMP. Any ideas what I can do to debug this further? Thanks, Rasmus
