On 4/24/24 09:06, Baoquan He wrote:
> On 04/19/24 at 10:55pm, Mingzheng Xing wrote:
>> On 4/19/24 21:58, Greg Kroah-Hartman wrote:
>>> On Fri, Apr 19, 2024 at 08:26:07PM +0800, Mingzheng Xing wrote:
>>>> On 4/19/24 18:44, Greg Kroah-Hartman wrote:
>>>>> On Tue, Apr 16, 2024 at 04:56:47PM +0800, Mingzheng Xing wrote:
>>>>>> This reverts commit 1d6cd2146c2b58bc91266db1d5d6a5f9632e14c0 which has been
>>>>>> merged into the mainline commit 39365395046f ("riscv: kdump: use generic
>>>>>> interface to simplify crashkernel reservation"), but the latter's series of
>>>>>> patches are not included in the 6.6 branch.
>>>>>>
>>>>>> This will result in the loss of Crash kernel data in /proc/iomem, and kdump
>>>>>> loading the kernel will also cause an error:
>>>>>>
>>>>>> ```
>>>>>> Memory for crashkernel is not reserved
>>>>>> Please reserve memory by passing"crashkernel=Y@X" parameter to kernel
>>>>>> Then try to loading kdump kernel
>>>>>> ```
>>>>>>
>>>>>> After revert this patch, verify that it works properly on QEMU riscv.
>>>>>>
>>>>>> Link: https://lore.kernel.org/linux-riscv/ZSiQRDGLZk7lpakE@MiWiFi-R3L-srv
>>>>>> Signed-off-by: Mingzheng Xing <xingmingzheng@xxxxxxxxxxx>
>>>>>> ---
>>>>>
>>>>> I do not understand, what branch is this for? Why have you not cc:ed
>>>>> any of the original developers here? Why does Linus's tree not have the
>>>>> same problem? And the first sentence above does not make much sense as
>>>>> a 6.6 change is merged into 6.7?
>>>>
>>>> Sorry, I'll try to explain it more clearly.
>>>>
>>>> This commit 1d6cd2146c2b ("riscv: kdump: fix crashkernel reserving problem
>>>> on RISC-V") should not have existed because this patch has been merged into
>>>> another larger patch [1]. Here is that complete series:
>>>
>>> What "larger patch"? It is in Linus's tree, so it's not part of
>>> something different, right? I'm confused.
>>>
>>
>> Hi, Greg
>>
>> The email Cc:ed to author Chen Jiahao was bounced by the system, so maybe
>> we can wait for Baoquan He to confirm.
>>
>> This is indeed a bit confusing. The Fixes: tag in 1d6cd2146c2b58 is a false
>> reference. If I understand correctly, this is similar to the following
>> scenario:
>>
>> A Fixes B, B doesn't go into linus mainline. C contains A, C goes into linus
>> mainline 6.7, and C has more reconstruction code. but A goes into 6.6, so
>> it doesn't make sense for A to be in the mainline, and there's no C in 6.6
>> but there's an A, thus resulting in an incomplete code that creates an error.
>
> Do you mean commit 1d6cd2146c2b58 ("iscv: kdump: fix crashkernel reserving
> problem on RISC-V") was mistakenly added into v6.6, but the commit which
> it fixed is not existing in v6.6?
>
Yeah, you're right, and it was merged into 6.7 by another commit
39365395046f ("riscv: kdump: use generic interface to simplify crashkernel reservation")
> I checked code, it does look like what you said, and it's truly
> confusing. If so, we should revert commit 1d6cd2146c2b58 ("iscv: kdump: fix
> crashkernel reserving problem on RISC-V") in v6.6.y to make kdump work
> on risc-v.
I agree. I built the 6.6.y branch kernel, tested it on qemu, and there is
no 'Crash kernel' entry in /proc/iomem. After revert, it's back to normal.
Thanks,
Mingzheng
