From: Sebastian Andrzej Siewior Date: Wed, 25 Jul 2018 14:02:38 +0200 Subject: [PATCH] arm64: fpsimd: Delay freeing memory in fpsimd_flush_thread() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz fpsimd_flush_thread() invokes kfree() via sve_free() within a preempt disabled section which is not working on -RT. Delay freeing of memory until preemption is enabled again. Signed-off-by: Sebastian Andrzej Siewior --- arch/arm64/kernel/fpsimd.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -213,6 +213,16 @@ static void sve_free(struct task_struct __sve_free(task); } +static void *sve_free_atomic(struct task_struct *task) +{ + void *sve_state = task->thread.sve_state; + + WARN_ON(test_tsk_thread_flag(task, TIF_SVE)); + + task->thread.sve_state = NULL; + return sve_state; +} + /* * TIF_SVE controls whether a task can use SVE without trapping while * in userspace, and also the way a task's FPSIMD/SVE state is stored @@ -1008,6 +1018,7 @@ void fpsimd_thread_switch(struct task_st void fpsimd_flush_thread(void) { int vl, supported_vl; + void *mem = NULL; if (!system_supports_fpsimd()) return; @@ -1020,7 +1031,7 @@ void fpsimd_flush_thread(void) if (system_supports_sve()) { clear_thread_flag(TIF_SVE); - sve_free(current); + mem = sve_free_atomic(current); /* * Reset the task vector length as required. @@ -1054,6 +1065,7 @@ void fpsimd_flush_thread(void) } put_cpu_fpsimd_context(); + kfree(mem); } /*