On Thu, 6 Dec 2018 at 14:19, Will Deacon <[email protected]> wrote: > > On Wed, Dec 05, 2018 at 12:48:54PM -0500, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" <[email protected]> > > > > 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/[email protected] > > > > Reported-by: Anders Roxell <[email protected]> > > Signed-off-by: Steven Rostedt (VMware) <[email protected]> > > --- > > 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 <[email protected]>
Tested-by: Anders Roxell <[email protected]> Cheers, Anders > > Thanks, Steve! > > Will
