Re: [PATCH] irq_work: Make irq_work_queue_on() NMI-safe again

From: Jun Miao
Date: Wed Apr 27 2022 - 09:18:33 EST

On 2022/4/27 20:26, Marco Elver wrote:
On Wed, 27 Apr 2022 at 03:49, Jun Miao <jun.miao@xxxxxxxxx> wrote:
Add To/Cc : KASAN/MEM , since I only used the scripts/
to irq_work.c file.

Jun Miao

On 2022/4/26 21:49, Jun Miao wrote:
We should not put NMI unsafe code in irq_work_queue_on().

The KASAN of kasan_record_aux_stack_noalloc() is not NMI safe. Because which
will call the spinlock. While the irq_work_queue_on() is also very carefully
carafted to be exactly that.

When unable CONFIG_SM or local CPU, the irq_work_queue_on() is even same to

irq_work_queue(). So delete KASAN instantly.

Fixes: e2b5bcf9f5ba ("irq_work: record irq_work_queue() call stack")
Suggested by: "Huang, Ying" <ying.huang@xxxxxxxxx>
Signed-off-by: Jun Miao <jun.miao@xxxxxxxxx>
I thought this had already been removed, but apparently there were 2

Acked-by: Marco Elver <elver@xxxxxxxxxx>

Sure, I also found this patch which is the same reason, maybe Peter Z forgot it. Let me make up a little.😉

Send V2 later.

Jun Miao
kernel/irq_work.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/kernel/irq_work.c b/kernel/irq_work.c
index 7afa40fe5cc4..e7f48aa8d8af 100644
--- a/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@ -20,7 +20,6 @@
#include <linux/smp.h>
#include <linux/smpboot.h>
#include <asm/processor.h>
-#include <linux/kasan.h>

static DEFINE_PER_CPU(struct llist_head, raised_list);
static DEFINE_PER_CPU(struct llist_head, lazy_list);
@@ -137,8 +136,6 @@ bool irq_work_queue_on(struct irq_work *work, int cpu)
if (!irq_work_claim(work))
return false;

- kasan_record_aux_stack_noalloc(work);
if (cpu != smp_processor_id()) {
/* Arch remote IPI send/receive backend aren't NMI safe */
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