On Wed, Dec 05, 2018 at 12:48:54PM -0500, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" <rost...@goodmis.org> > > It has been reported that ftrace_replace_code() which is called by > ftrace_modify_all_code() can cause a soft lockup warning for an > allmodconfig kernel. This is because all the debug options enabled > causes the loop in ftrace_replace_code() (which loops over all the > functions being enabled where there can be 10s of thousands), is too > slow, and never schedules out. > > To solve this, setting FTRACE_SCHEDULABLE to the command passed into > ftrace_replace_code() will make it call cond_resched() in the loop, > which prevents the soft lockup warning from triggering. > > Link: http://lkml.kernel.org/r/20181204192903.8193-1-anders.rox...@linaro.org > > Reported-by: Anders Roxell <anders.rox...@linaro.org> > Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org> > --- > arch/arm64/kernel/ftrace.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c > index 57e962290df3..9a8de0a79f97 100644 > --- a/arch/arm64/kernel/ftrace.c > +++ b/arch/arm64/kernel/ftrace.c > @@ -193,6 +193,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace > *rec, > > void arch_ftrace_update_code(int command) > { > + command |= FTRACE_SCHEDULABLE; > ftrace_modify_all_code(command); > }
Bikeshed: I'd probably go for FTRACE_MAY_SLEEP, but I'm not going to die on that hill so... Acked-by: Will Deacon <will.dea...@arm.com> Thanks, Steve! Will