[PATCH] Revert "riscv: kdump: fix crashkernel reserving problem on RISC-V"

[Greg Kroah-Hartman]

On Wed, Apr 24, 2024 at 11:40:16AM +0800, Mingzheng Xing wrote:
> On 4/23/24 21:12, Greg Kroah-Hartman wrote:
> > On Fri, Apr 19, 2024 at 10:55:44PM +0800, 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 at 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 at iscas.ac.cn>
> >>>>>> ---
> >>>>>
> >>>>> 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.
> >>
> >> The link I quoted [1] shows that Baoquan had expressed an opinion on this
> >> at the time.
> >>
> >> Link: https://lore.kernel.org/linux-riscv/ZSiQRDGLZk7lpakE@MiWiFi-R3L-srv [1]
> > 
> > I'm sorry, but I still do not understand what I need to do here for a
> > stable branch.  Do I need to apply something?  Revert something?
> > Something else?
> 
> Hi, Greg
> 
> I saw Baoquan's reply in thread[1], thanks Baoquan for confirming.
> 
> So I think the right thing to do would be just to REVERT the commit
> 1d6cd2146c2b ("riscv: kdump: fix crashkernel reserving problem on RISC-V")
> in the 6.6.y branch, which is exactly the patch I submitted. If I need to
> make changes to my commit message, feel free to let me know and I'll post
> the second version.
> 
> Link: https://lore.kernel.org/stable/ZihbAYMOI4ylazpt@MiWiFi-R3L-srv [1]

Can someone just send me a patch series showing EXACTLY what needs to be
done here, as I am _still_ confused.

thanks,

greg k-h