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

[chenjiahao (C)]

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@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> > ---
> >   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