linux-kernel - Re: [PATCH] mm: Give kmap_lock before call flush_tlb_kernel_rang，avoid kmap

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Message-ID: <Zo0laCcWwAoL0bFu@casper.infradead.org>
Date: Tue, 9 Jul 2024 12:56:24 +0100
From: Matthew Wilcox <willy@...radead.org>
To: zhangchun <zhang.chuna@....com>
Cc: akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, jiaoxupo@....com,
	zhang.zhengming@....com, zhang.zhansheng@....com,
	shaohaojize@....com
Subject: Re: [PATCH] mm: Give kmap_lock before call flush_tlb_kernel_rang，avoid kmap_high deadlock.

On Tue, Jul 09, 2024 at 05:17:38PM +0800, zhangchun wrote:
> +++ b/mm/highmem.c
> @@ -220,8 +220,11 @@ static void flush_all_zero_pkmaps(void)
>  		set_page_address(page, NULL);
>  		need_flush = 1;
>  	}
> -	if (need_flush)
> +	if (need_flush) {
> +		spin_unlock(&kmap_lock);

should this be a raw spin_unlock(), or should it be unlock_kmap()?
ie when ARCH_NEEDS_KMAP_HIGH_GET is set, do we also need to re-enable
interrupts here?

>  		flush_tlb_kernel_range(PKMAP_ADDR(0), PKMAP_ADDR(LAST_PKMAP));
> +		spin_lock(&kmap_lock);
> +	}
>  }
>  
>  void __kmap_flush_unused(void)
> -- 
> 1.8.3.1
> 
>