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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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/5.10/older/patches-5.10.21-rt34.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 <bigeasy@linutronix.de>
---
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
@@ -226,6 +226,16 @@ 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
@@ -1022,6 +1032,7 @@ void fpsimd_thread_switch(struct task_st
void fpsimd_flush_thread(void)
{
int vl, supported_vl;
+ void *mem = NULL;
if (!system_supports_fpsimd())
return;
@@ -1034,7 +1045,7 @@ 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.
@@ -1068,6 +1079,7 @@ void fpsimd_flush_thread(void)
}
put_cpu_fpsimd_context();
+ kfree(mem);
}
/*
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