From 8d430a85f9b781be138482f834b7080e14d3b468 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Thu, 29 Jul 2021 12:52:14 +0200
Subject: [PATCH] arm64/sve: Delay freeing memory in fpsimd_flush_thread()
References: SLE Realtime Extension
Patch-mainline: Queued in subsystem maintainer repository
Git-commit: 83825fd82df1021b7210d3998aa26e30859dd032
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
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>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
arch/arm64/kernel/fpsimd.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 3599b9a2f1df..4dda3a12e133 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1032,6 +1032,7 @@ void fpsimd_thread_switch(struct task_struct *next)
void fpsimd_flush_thread(void)
{
+ void *sve_state = NULL;
int vl, supported_vl;
if (!system_supports_fpsimd())
@@ -1045,7 +1046,10 @@ void fpsimd_flush_thread(void)
if (system_supports_sve()) {
clear_thread_flag(TIF_SVE);
- sve_free(current);
+
+ /* Defer kfree() while in atomic context */
+ sve_state = current->thread.sve_state;
+ current->thread.sve_state = NULL;
/*
* Reset the task vector length as required.
@@ -1079,6 +1083,7 @@ void fpsimd_flush_thread(void)
}
put_cpu_fpsimd_context();
+ kfree(sve_state);
}
/*