From e4c07bf9867aeaec14bac042fbbd50d885f6ed3a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Wed, 5 Dec 2018 12:48:54 -0500 Subject: arm64: ftrace: Set FTRACE_MAY_SLEEP before ftrace_modify_all_code() 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_MAY_SLEEP 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.roxell@linaro.org Link: http://lkml.kernel.org/r/20181205183304.000714627@goodmis.org Acked-by: Will Deacon Reported-by: Anders Roxell Tested-by: Anders Roxell Signed-off-by: Steven Rostedt (VMware) --- arch/arm64/kernel/ftrace.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm64/kernel/ftrace.c') diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index 57e962290df3..57d4e936a176 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_MAY_SLEEP; ftrace_modify_all_code(command); } -- cgit v1.2.3