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Message-ID: <0c29e157-20dd-2f07-d1e5-a9f2ed7e28eb@intel.com>
Date:   Wed, 27 Apr 2022 21:59:56 +0800
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Subject: Re: [PATCH] irq_work: Make irq_work_queue_on() NMI-safe again
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To:     <elver@google.com>, <dvyukov@google.com>, <ryabinin.a.a@gmail.com>,
        <peterz@infradead.org>
CC:     <bigeasy@linutronix.de>, <qiang1.zhang@intel.com>,
        <andreyknvl@gmail.com>, <kasan-dev@googlegroups.com>,
        <linux-kernel@vger.kernel.org>, <akpm@linux-foundation.org>
References: <20220427135050.20566-1-jun.miao@intel.com>
From:   Jun Miao <jun.miao@intel.com>
In-Reply-To: <20220427135050.20566-1-jun.miao@intel.com>
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Sorry, please ignore!


On 2022/4/27 21:50, 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
> carfted to be exactly that.
> When unable CONFIG_SMP 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@intel.com>
> Signed-off-by: Jun Miao <jun.miao@intel.com>
> Acked-by: Marco Elver <elver@google.com>
> ---
>   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);
> -
>   	preempt_disable();
>   	if (cpu != smp_processor_id()) {
>   		/* Arch remote IPI send/receive backend aren't NMI safe */