From: "Leizhen (ThunderTown)" <thunder.leizhen@huawei.com>
To: Baoquan He <bhe@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
<x86@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
<linux-kernel@vger.kernel.org>, Dave Young <dyoung@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>,
Eric Biederman <ebiederm@xmission.com>,
<kexec@lists.infradead.org>, Will Deacon <will@kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
<devicetree@vger.kernel.org>, "Jonathan Corbet" <corbet@lwn.net>,
<linux-doc@vger.kernel.org>, Randy Dunlap <rdunlap@infradead.org>,
Feng Zhou <zhoufeng.zf@bytedance.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Chen Zhou <dingguo.cz@antgroup.com>,
"John Donnelly" <John.p.donnelly@oracle.com>,
Dave Kleikamp <dave.kleikamp@oracle.com>
Subject: Re: [PATCH v24 3/6] arm64: kdump: Reimplement crashkernel=X
Date: Sat, 7 May 2022 11:37:03 +0800 [thread overview]
Message-ID: <9f6fdbb8-b6c5-3ca0-31b6-617175739e81@huawei.com> (raw)
In-Reply-To: <YnXUSBcFmEpxaqBf@MiWiFi-R3L-srv>
On 2022/5/7 10:07, Baoquan He wrote:
> On 05/07/22 at 09:34am, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2022/5/7 7:10, 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 think maybe we can leave it unchanged. If the user configures two memory ranges,
>> we'd better apply for two. Otherwise, he'll be confused when he inquires. Currently,
>> crash_low_size is non-zero only when 'crashkernel=Y,low' is explicitly configured.
>
> Then user need know the system information, e.g how much is the high
> memory, low memory, if CONFIG_ZONE_DMA|DMA32 is enabled. And we need
> describe these cases in document. Any corner case or exception need
> be noted if we don't handle it in code.
>
> Caring about this very much because we have CI with existed test cases
> to run on the system, and QA will check these manually too. Support
> engineer need detailed document if anything special but happened.
> Anything unclear or uncovered will be reported as bug to our kernel dev.
> Guess your company do the similar thing like this.
>
> This crashkerne,high and crashkernel,low reservation is special if we
> allow ,high, ,low existing in the same zone. Imagine on system with
> CONFIG_ZONE_DMA|DMA32 disabled, people copy the crashkernel=512M,high
> and crashkernel=128M,low from other system, and he could get
> crash_res at [5G, 5G+512M], while crash_low_res at [6G, 6G+128M]. Guess
> how they will judge us.
OK, I got it.
>
>>
>>>
>>> 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.
>>>
>>>> + 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
>>>>
>>>
>>> .
>>>
>>
>> --
>> Regards,
>> Zhen Lei
>>
>
> .
>
--
Regards,
Zhen Lei
next prev parent reply other threads:[~2022-05-07 3:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-06 11:43 [PATCH v24 0/6] support reserving crashkernel above 4G on arm64 kdump Zhen Lei
2022-05-06 11:43 ` [PATCH v24 1/6] kdump: return -ENOENT if required cmdline option does not exist Zhen Lei
2022-05-06 11:43 ` [PATCH v24 2/6] arm64: Use insert_resource() to simplify code Zhen Lei
2022-05-06 11:43 ` [PATCH v24 3/6] arm64: kdump: Reimplement crashkernel=X Zhen Lei
2022-05-06 23:10 ` Baoquan He
2022-05-07 1:34 ` Leizhen (ThunderTown)
2022-05-07 2:07 ` Baoquan He
2022-05-07 3:37 ` Leizhen (ThunderTown) [this message]
2022-05-07 9:35 ` Leizhen (ThunderTown)
2022-05-07 11:49 ` Leizhen (ThunderTown)
2022-05-07 12:20 ` Leizhen (ThunderTown)
2022-05-07 13:22 ` Baoquan He
2022-05-07 17:30 ` John Donnelly
2022-05-07 18:50 ` Catalin Marinas
2022-05-09 4:04 ` Baoquan He
2022-05-06 11:44 ` [PATCH v24 4/6] of: fdt: Add memory for devices by DT property "linux,usable-memory-range" Zhen Lei
2022-05-06 23:15 ` Baoquan He
2022-05-06 11:44 ` [PATCH v24 5/6] of: Support more than one crash kernel regions for kexec -s Zhen Lei
2022-05-06 23:17 ` Baoquan He
2022-05-07 1:42 ` Leizhen (ThunderTown)
2022-05-07 2:36 ` Baoquan He
2022-05-06 11:44 ` [PATCH v24 6/6] docs: kdump: Update the crashkernel description for arm64 Zhen Lei
2022-05-06 23:14 ` Baoquan He
2022-05-07 1:41 ` Leizhen (ThunderTown)
2022-05-07 3:23 ` Leizhen (ThunderTown)
2022-05-07 3:30 ` Baoquan He
2022-05-07 18:22 ` Catalin Marinas
2022-05-09 4:05 ` Baoquan He
2022-05-07 19:12 ` [PATCH v24 0/6] support reserving crashkernel above 4G on arm64 kdump Catalin Marinas
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