linux-kernel - Re: [PATCH -next] riscv: kdump: fix crashkernel reserving problem on RISC-V

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Message-ID: <c590ac5d-91b9-ec3b-6899-a18c16c9f980@huawei.com>
Date:   Fri, 22 Sep 2023 17:33:24 +0800
From:   "chenjiahao (C)" <chenjiahao16@...wei.com>
To:     Baoquan He <bhe@...hat.com>
CC:     <thunder.leizhen@...wei.com>, <paul.walmsley@...ive.com>,
        <palmer@...belt.com>, <aou@...s.berkeley.edu>,
        <conor.dooley@...rochip.com>, <alexghiti@...osinc.com>,
        <ajones@...tanamicro.com>, <jszhang@...nel.org>,
        <sunilvl@...tanamicro.com>, <robh@...nel.org>,
        <bjorn@...osinc.com>, <zephray@...look.com>,
        <akpm@...ux-foundation.org>, <linux-riscv@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next] riscv: kdump: fix crashkernel reserving problem on
 RISC-V


On 2023/9/22 15:16, Baoquan He wrote:
> Hi Jiahao,
>
> On 09/22/23 at 11:07am, Chen Jiahao wrote:
>> When testing on risc-v QEMU environment with "crashkernel="
>> parameter enabled, a problem occurred with the following
>> message:
>>
>> [    0.000000] crashkernel low memory reserved: 0xf8000000 - 0x100000000 (128 MB)
>> [    0.000000] crashkernel reserved: 0x0000000177e00000 - 0x0000000277e00000 (4096 MB)
>> [    0.000000] ------------[ cut here ]------------
>> [    0.000000] WARNING: CPU: 0 PID: 0 at kernel/resource.c:779 __insert_resource+0x8e/0xd0
>> [    0.000000] Modules linked in:
>> [    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 6.6.0-rc2-next-20230920 #1
>> [    0.000000] Hardware name: riscv-virtio,qemu (DT)
>> [    0.000000] epc : __insert_resource+0x8e/0xd0
>> [    0.000000]  ra : insert_resource+0x28/0x4e
>> [    0.000000] epc : ffffffff80017344 ra : ffffffff8001742e sp : ffffffff81203db0
>> [    0.000000]  gp : ffffffff812ece98 tp : ffffffff8120dac0 t0 : ff600001f7ff2b00
>> [    0.000000]  t1 : 0000000000000000 t2 : 3428203030303030 s0 : ffffffff81203dc0
>> [    0.000000]  s1 : ffffffff81211e18 a0 : ffffffff81211e18 a1 : ffffffff81289380
>> [    0.000000]  a2 : 0000000277dfffff a3 : 0000000177e00000 a4 : 0000000177e00000
>> [    0.000000]  a5 : ffffffff81289380 a6 : 0000000277dfffff a7 : 0000000000000078
>> [    0.000000]  s2 : ffffffff81289380 s3 : ffffffff80a0bac8 s4 : ff600001f7ff2880
>> [    0.000000]  s5 : 0000000000000280 s6 : 8000000a00006800 s7 : 000000000000007f
>> [    0.000000]  s8 : 0000000080017038 s9 : 0000000080038ea0 s10: 0000000000000000
>> [    0.000000]  s11: 0000000000000000 t3 : ffffffff80a0bc00 t4 : ffffffff80a0bc00
>> [    0.000000]  t5 : ffffffff80a0bbd0 t6 : ffffffff80a0bc00
>> [    0.000000] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
>> [    0.000000] [<ffffffff80017344>] __insert_resource+0x8e/0xd0
>> [    0.000000] ---[ end trace 0000000000000000 ]---
>> [    0.000000] Failed to add a Crash kernel resource at 177e00000
>>
>> The crashkernel memory has been allocated successfully, whereas
>> it failed to insert into iomem_resource. This is due to the
> This is a warning, not a failure, right? Inserting crashk_*res into
> iomem_resource has been successful, just the repeated inserting cause
> the warning. Maybe, we should tell this in log clearly? Other than minor
> concern, this looks good to me, thanks for the testing and this fix:

Thanks for reviewing. Actually this is not only a warning message.
Since when failure occurs in riscv's init_resources(),

error:
	release_child_resources(&iomem_resource);

will get called, already added crashkernel memory will hence
get removed. To verify this, I have checked but cannot find
crashkernel memory in /proc/iomem when this problem occurs.

But you are right, it is necessary to make it clear what will
eventually happen in commit message. I will update a v2 patch later
to add these info.

Thanks,
Jiahao


>
> Acked-by: Baoquan He <bhe@...hat.com>
>
> Thanks
> Baoquan
>
>> unique reserving logic in risc-v arch specific code, i.e.
>> crashk_res/crashk_low_res will be added into iomem_resource
>> later in init_resources(), which is not aligned with current
>> unified reserving logic in reserve_crashkernel_generic()/
>> reserve_crashkernel_low().
>>
>> Removing the arch specific code within #ifdef CONFIG_KEXEC_CORE
>> in init_resources() to fix above problem.
>>
>> Fixes: 31549153088e ("riscv: kdump: use generic interface to simplify crashkernel reservation")
>> Signed-off-by: Chen Jiahao <chenjiahao16@...wei.com>
>> ---
>>   arch/riscv/kernel/setup.c | 13 -------------
>>   1 file changed, 13 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> index e600aab116a4..aac853ae4eb7 100644
>> --- a/arch/riscv/kernel/setup.c
>> +++ b/arch/riscv/kernel/setup.c
>> @@ -173,19 +173,6 @@ static void __init init_resources(void)
>>   	if (ret < 0)
>>   		goto error;
>>   
>> -#ifdef CONFIG_KEXEC_CORE
>> -	if (crashk_res.start != crashk_res.end) {
>> -		ret = add_resource(&iomem_resource, &crashk_res);
>> -		if (ret < 0)
>> -			goto error;
>> -	}
>> -	if (crashk_low_res.start != crashk_low_res.end) {
>> -		ret = add_resource(&iomem_resource, &crashk_low_res);
>> -		if (ret < 0)
>> -			goto error;
>> -	}
>> -#endif
>> -
>>   #ifdef CONFIG_CRASH_DUMP
>>   	if (elfcorehdr_size > 0) {
>>   		elfcorehdr_res.start = elfcorehdr_addr;
>> -- 
>> 2.34.1
>>