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); } -- 2.19.1
