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Message-ID: <5284b96b-06a8-6d84-ec87-44f3c112c89b@huawei.com>
Date: Thu, 18 Jul 2024 21:18:43 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: Baoquan He <bhe@...hat.com>
CC: <linux@...linux.org.uk>, <catalin.marinas@....com>, <will@...nel.org>,
<paul.walmsley@...ive.com>, <palmer@...belt.com>, <aou@...s.berkeley.edu>,
<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
<dave.hansen@...ux.intel.com>, <hpa@...or.com>, <vgoyal@...hat.com>,
<dyoung@...hat.com>, <arnd@...db.de>, <afd@...com>,
<linus.walleij@...aro.org>, <akpm@...ux-foundation.org>,
<eric.devolder@...cle.com>, <gregkh@...uxfoundation.org>,
<javierm@...hat.com>, <deller@....de>, <robh@...nel.org>,
<hbathini@...ux.ibm.com>, <thunder.leizhen@...wei.com>,
<chenjiahao16@...wei.com>, <linux-kernel@...r.kernel.org>,
<kexec@...ts.infradead.org>, <linux-arm-kernel@...ts.infradead.org>,
<linux-riscv@...ts.infradead.org>
Subject: Re: [PATCH v3 1/3] crash: Fix x86_32 crash memory reserve dead loop
bug
On 2024/7/18 19:10, Baoquan He wrote:
> On 07/18/24 at 11:54am, Jinjie Ruan wrote:
>> On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=1G,high"
>> will cause system stall as below:
>>
>> ACPI: Reserving FACP table memory at [mem 0x3ffe18b8-0x3ffe192b]
>> ACPI: Reserving DSDT table memory at [mem 0x3ffe0040-0x3ffe18b7]
>> ACPI: Reserving FACS table memory at [mem 0x3ffe0000-0x3ffe003f]
>> ACPI: Reserving APIC table memory at [mem 0x3ffe192c-0x3ffe19bb]
>> ACPI: Reserving HPET table memory at [mem 0x3ffe19bc-0x3ffe19f3]
>> ACPI: Reserving WAET table memory at [mem 0x3ffe19f4-0x3ffe1a1b]
>> 143MB HIGHMEM available.
>> 879MB LOWMEM available.
>> mapped low ram: 0 - 36ffe000
>> low ram: 0 - 36ffe000
>> (stall here)
>>
>> The reason is that the CRASH_ADDR_LOW_MAX is equal to CRASH_ADDR_HIGH_MAX
>> on x86_32, the first high crash kernel memory reservation will fail, then
>> go into the "retry" loop and never came out as below.
>>
>> -> reserve_crashkernel_generic() and high is true
>> -> alloc at [CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX] fail
>> -> alloc at [0, CRASH_ADDR_LOW_MAX] fail and repeatedly
>> (because CRASH_ADDR_LOW_MAX = CRASH_ADDR_HIGH_MAX).
>>
>> Fix it by prevent crashkernel=,high from being parsed successfully on 32bit
>> system with a architecture-defined macro.
>>
>> After this patch, the 'crashkernel=,high' for 32bit system can't succeed,
>> and it has no chance to call reserve_crashkernel_generic(), therefore this
>> issue on x86_32 is solved.
>>
>> Fixes: 9c08a2a139fe ("x86: kdump: use generic interface to simplify crashkernel reservation code")
>> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
>> Signed-off-by: Baoquan He <bhe@...hat.com>
>
> Just adding my Suggested-by is fine. If multiple people cooperate on one
> patch, the Co-developed-by tag is needed. As a maintainer, I prefer to
> have the Suggested-by tag in this case.
Hi, Baoquan, I wonder if riscv32 have a similar problem, but I'm not sure.
>
>> Tested-by: Jinjie Ruan <ruanjinjie@...wei.com>
>
> You can't add Tested-by tag for your own patch. When you post patch,
> testing it is your obligation.
>
> Other than these tag adding concerns, this patch looks good to me. You
> can post v4 to update and add my:
>
> Acked-by: Baoquan He <bhe@...hat.com>
>
>> ---
>> v3:
>> - Fix it as Baoquan suggested.
>> - Update the commit message.
>> v2:
>> - Peel off the other two patches.
>> - Update the commit message and fix tag.
>> ---
>> arch/arm64/include/asm/crash_reserve.h | 2 ++
>> arch/riscv/include/asm/crash_reserve.h | 2 ++
>> arch/x86/include/asm/crash_reserve.h | 1 +
>> kernel/crash_reserve.c | 2 +-
>> 4 files changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/crash_reserve.h b/arch/arm64/include/asm/crash_reserve.h
>> index 4afe027a4e7b..bf362c1a612f 100644
>> --- a/arch/arm64/include/asm/crash_reserve.h
>> +++ b/arch/arm64/include/asm/crash_reserve.h
>> @@ -7,4 +7,6 @@
>>
>> #define CRASH_ADDR_LOW_MAX arm64_dma_phys_limit
>> #define CRASH_ADDR_HIGH_MAX (PHYS_MASK + 1)
>> +
>> +#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
>> #endif
>> diff --git a/arch/riscv/include/asm/crash_reserve.h b/arch/riscv/include/asm/crash_reserve.h
>> index 013962e63587..8d7a8fc1d459 100644
>> --- a/arch/riscv/include/asm/crash_reserve.h
>> +++ b/arch/riscv/include/asm/crash_reserve.h
>> @@ -7,5 +7,7 @@
>> #define CRASH_ADDR_LOW_MAX dma32_phys_limit
>> #define CRASH_ADDR_HIGH_MAX memblock_end_of_DRAM()
>>
>> +#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
>> +
>> extern phys_addr_t memblock_end_of_DRAM(void);
>> #endif
>> diff --git a/arch/x86/include/asm/crash_reserve.h b/arch/x86/include/asm/crash_reserve.h
>> index 7835b2cdff04..24c2327f9a16 100644
>> --- a/arch/x86/include/asm/crash_reserve.h
>> +++ b/arch/x86/include/asm/crash_reserve.h
>> @@ -26,6 +26,7 @@ extern unsigned long swiotlb_size_or_default(void);
>> #else
>> # define CRASH_ADDR_LOW_MAX SZ_4G
>> # define CRASH_ADDR_HIGH_MAX SZ_64T
>> +#define HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
>> #endif
>>
>> # define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
>> diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
>> index 5b2722a93a48..c5213f123e19 100644
>> --- a/kernel/crash_reserve.c
>> +++ b/kernel/crash_reserve.c
>> @@ -306,7 +306,7 @@ int __init parse_crashkernel(char *cmdline,
>> /* crashkernel=X[@offset] */
>> ret = __parse_crashkernel(cmdline, system_ram, crash_size,
>> crash_base, NULL);
>> -#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>> +#ifdef HAVE_ARCH_CRASHKERNEL_RESERVATION_HIGH
>> /*
>> * If non-NULL 'high' passed in and no normal crashkernel
>> * setting detected, try parsing crashkernel=,high|low.
>> --
>> 2.34.1
>>
>
>
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