Messages in this thread | | | Date | Fri, 31 Mar 2023 19:36:42 +0800 | Subject | Re: [PATCH -next v2 1/2] riscv: kdump: Implement crashkernel=X,[high,low] | From | "chenjiahao (C)" <> |
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On 2023/3/31 7:32, Baoquan He wrote: > On 03/30/23 at 09:40pm, chenjiahao (C) wrote: > ...... >> Agreed, I will clean this up later in next version. >>>> + if (ret || !crash_size) >>>> + return; >>>> + >>>> + /* >>>> + * crashkernel=Y,low is valid only when crashkernel=X,high >>>> + * is passed and high memory is reserved successful. >>>> + */ >>>> + ret = parse_crashkernel_low(boot_command_line, 0, &crash_low_size, &crash_base); >>>> + if (ret == -ENOENT) >>>> + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; >>>> + else if (ret) >>>> + return; >>>> + >>>> + search_start = dma32_phys_limit; >>>> + } else if (ret || !crash_size) { >>>> + /* Invalid argument value specified */ >>>> return; >>>> + } >>>> crash_size = PAGE_ALIGN(crash_size); >>>> @@ -1201,16 +1246,26 @@ static void __init reserve_crashkernel(void) >>>> */ >>>> crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, >>>> search_start, >>>> - min(search_end, (unsigned long) SZ_4G)); >>>> + min(search_end, (unsigned long)dma32_phys_limit)); >>>> if (crash_base == 0) { >>> The above conditional check isn't right. If crashkernel=size@offset >>> specified, the reservation failure won't trigger retry. This seems to be >>> originally introduced by old commit, while this need be fixed firstly. >> Just a little curious about the rule to cope with this specific case. If >> "crashkernel=size@offset" was passed >> >> but reserve failed, should try again to allocate in high memory, regardless >> the specified size@offset, >> >> or just throw a warning and return? Since I noticed the current logic here >> on Arm64 is to check if !fixed_base first > Yeah, we need mark the "crashkernel=size@offset" case and avoid to > retry. Because you won't succeed if memblock has already failed to > reserve an unavailable memory region, retry is meaningless. This has > been done in x86, arm64.
Make sense, thanks.
Actually, in my previous tests, the result in this case is the same as expectation, i.e. when allocating "crashkernel=size@offset" failed on low memory, it would retry but return on failure. Since the search_end is assigned with offset + size, which is lower than DMA32 limit, the second allocation is definitely invalid.
But for sure, to make the code easy to read and eradicate other possible corner cases, I will check if !fixed_base first on retry.
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