linux-kernel - Re: [PATCH] RISC-V: Remove IORESOURCE_BUSY flag for no-map reserved memory

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Date:   Wed, 11 May 2022 14:27:34 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Xianting Tian <xianting.tian@...ux.alibaba.com>,
        paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, akpm@...ux-foundation.org,
        anup@...infault.org, wangkefeng.wang@...wei.com, rppt@...nel.org,
        alex@...ti.fr, twd2.me@...il.com, seanjc@...gle.com,
        petr.pavlu@...e.com, atishp@...osinc.com
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        guoren@...nel.org, jianghuaming.jhm@...baba-inc.com,
        Nick Kossifidis <mick@....forth.gr>
Subject: Re: [PATCH] RISC-V: Remove IORESOURCE_BUSY flag for no-map reserved
 memory

On 11.05.22 13:24, Xianting Tian wrote:
> Commit 00ab027a3b82 ("RISC-V: Add kernel image sections to the resource tree")
> added IORESOURCE_BUSY flag for no-map reserved memory, this casued
> devm_ioremap_resource() failed for the no-map reserved memory in subsequent
> operations of related driver, so remove the IORESOURCE_BUSY flag.
> 
> The code to reproduce the issue,
> dts:
> 	mem0: memory@...00000 {
>                 reg = <0x0 0xa0000000 0 0x1000000>;
>                 no-map;
>         };
> 
> 	&test {
> 		status = "okay";
> 		memory-region = <&mem0>;
> 	};
> 
> code:
> 	np = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
> 	ret = of_address_to_resource(np, 0, &r);
> 	base = devm_ioremap_resource(&pdev->dev, &r);
> 	// base = -EBUSY
> 
> Fixes: 00ab027a3b82 ("RISC-V: Add kernel image sections to the resource tree")
> Reported-by: Huaming Jiang <jianghuaming.jhm@...baba-inc.com>
> Reviewed-by: Guo Ren <guoren@...nel.org>
> CC: Nick Kossifidis <mick@....forth.gr>
> Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
> ---
>  arch/riscv/kernel/setup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 834eb652a7b9..71f2966b1474 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -214,7 +214,7 @@ static void __init init_resources(void)
>  
>  		if (unlikely(memblock_is_nomap(region))) {
>  			res->name = "Reserved";
> -			res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> +			res->flags = IORESOURCE_MEM;
>  		} else {
>  			res->name = "System RAM";
>  			res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;

I assume the "Reserved" part is essentially unused by the kernel correct?

-- 
Thanks,

David / dhildenb