After commit 5e66a5bdad69 ("ftrace: Fix rcu warn in ftrace_location()"), lockdep still complain that:

include/linux/rcupdate.h:646 rcu_read_lock() used illegally while idle!

As Xu suggested, lockdep check can be disabled when exectue ftrace_int3_handler(), refer to mainline commit ba1f2b2eaa2a ("x86/entry: Fix NMI vs IRQ state tracking").

Fixes: 5e66a5bdad69 ("ftrace: Fix rcu warn in ftrace_location()") Suggested-by: Xu Kuohai xukuohai@huawei.com Signed-off-by: Zheng Yejian zhengyejian1@huawei.com --- arch/x86/kernel/traps.c | 12 +++++++++--- kernel/trace/ftrace.c | 10 ++-------- 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e832a9becc19..343c21fa3fad 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -585,9 +585,15 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) * ftrace must be first, everything else may cause a recursive crash. * See note by declaration of modifying_ftrace_code in ftrace.c */ - if (unlikely(atomic_read(&modifying_ftrace_code)) && - ftrace_int3_handler(regs)) - return; + if (unlikely(atomic_read(&modifying_ftrace_code))) { + int ret; + + lockdep_off(); + ret = ftrace_int3_handler(regs); + lockdep_on(); + if (ret) + return; + } #endif if (poke_int3_handler(regs)) return; diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index ad4440da5b78..6704150cb655 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -1581,12 +1581,7 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) key.ip = start; key.flags = end; /* overload flags, as it is unsigned long */

- /* - * It is in atomic context when called from ftrace_int3_handler(), - * in this case rcu lock is not needed. - */ - if (!in_atomic()) - rcu_read_lock(); + rcu_read_lock(); for (pg = ftrace_pages_start; pg; pg = pg->next) { if (pg->index == 0 || end < pg->records[0].ip || @@ -1600,8 +1595,7 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) break; } } - if (!in_atomic()) - rcu_read_unlock(); + rcu_read_unlock();

return ip; }