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

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Message-ID: <f12c2576-1bd4-970d-4435-59273c5de0fc@linux.alibaba.com>
Date:   Wed, 11 May 2022 20:37:26 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     David Hildenbrand <david@...hat.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


在 2022/5/11 下午8:27, David Hildenbrand 写道:
> 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?

I think we may use it, actually we found the issue in our product after 
merged kdump functionality.

Actually, the code didn't add IORESOURCE_BUSY for no-map reserved memory 
before 00ab027a3b82 merged,  so it is a typo for commit 00ab027a3b82 to 
add IORESOURCE_BUSY?

>