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

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Date:   Fri, 22 Sep 2023 18:28:27 +0800
From:   Baoquan He <bhe@...hat.com>
To:     "chenjiahao (C)" <chenjiahao16@...wei.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 09/22/23 at 05:33pm, chenjiahao (C) wrote:
> 
> 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.

I see, I was mistaken then. Thanks for telling.