From: Sebastian Andrzej Siewior Date: Wed, 14 Aug 2019 17:08:58 +0200 Subject: [PATCH] arm64: preempt: Check preemption level before looking at lazy-preempt Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.9-rt3.tar.xz Before evaluating the lazy-preempt state it must be ensure that the preempt-count is zero. Signed-off-by: Sebastian Andrzej Siewior --- arch/arm64/include/asm/preempt.h | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/arm64/include/asm/preempt.h +++ b/arch/arm64/include/asm/preempt.h @@ -73,6 +73,8 @@ static inline bool __preempt_count_dec_a if (!pc || !READ_ONCE(ti->preempt_count)) return true; #ifdef CONFIG_PREEMPT_LAZY + if ((pc & ~PREEMPT_NEED_RESCHED)) + return false; if (current_thread_info()->preempt_lazy_count) return false; return test_thread_flag(TIF_NEED_RESCHED_LAZY);