Re: [PATCH v24 3/6] arm64: kdump: Reimplement crashkernel=X

[John Donnelly]

On 5/6/22 6:10 PM, Baoquan He wrote:
> On 05/06/22 at 07:43pm, Zhen Lei wrote:
> ......
> > @@ -118,8 +162,7 @@ static void __init reserve_crashkernel(void)
> >   	if (crash_base)
> >   		crash_max = crash_base + crash_size;
> >   
> > -	/* Current arm64 boot protocol requires 2MB alignment */
> > -	crash_base = memblock_phys_alloc_range(crash_size, SZ_2M,
> > +	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> >   					       crash_base, crash_max);
> >   	if (!crash_base) {
> >   		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> > @@ -127,6 +170,11 @@ static void __init reserve_crashkernel(void)
> >   		return;
> >   	}
> >   
>
> There's corner case missed, e.g
> 1) ,high and ,low are specified, CONFIG_ZONE_DMA|DMA32 is not enabled;
> 2) ,high and ,low are specified, the whole system memory is under 4G.
>
> Below judgement can filter them away:
>          
> 	if (crash_base > arm64_dma_phys_limit && crash_low_size &&
> 	    reserve_crashkernel_low(crash_low_size)) {
>
> What's your opinion? Leave it and add document to notice user, or fix it
> with code change >
> I would suggest merging this series, Lei can add this corner case
> handling on top. Since this is a newly added support, we don't have
> to make it one step. Doing step by step can make reviewing easier.

Lets get this added and tested with a broader audience. It has been in 
review since March, 4th 2019 - 3+ years. I applaud Zhen for his 
endurance and patience in carrying this for so long.


> > +	if (crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> > +		memblock_phys_free(crash_base, crash_size);
> > +		return;
> > +	}
> > +
> >   	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
> >   		crash_base, crash_base + crash_size, crash_size >> 20);
> >   
> > @@ -135,6 +183,9 @@ static void __init reserve_crashkernel(void)
> >   	 * map. Inform kmemleak so that it won't try to access it.
> >   	 */
> >   	kmemleak_ignore_phys(crash_base);
> > +	if (crashk_low_res.end)
> > +		kmemleak_ignore_phys(crashk_low_res.start);
> > +
> >   	crashk_res.start = crash_base;
> >   	crashk_res.end = crash_base + crash_size - 1;
> >   	insert_resource(&iomem_resource, &crashk_res);
> > --
> > 2.25.1