linux-kernel - Re: [PATCH v3] memblock,arm64: Expand the static memblock memory table

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Message-ID: <Yp5x32CsI/BBcHf9@fedora>
Date:   Mon, 6 Jun 2022 14:30:07 -0700
From:   Darren Hart <darren@...amperecomputing.com>
To:     Zhou Guanghui <zhouguanghui1@...wei.com>
Cc:     akpm@...ux-foundation.org, rppt@...nel.org, will@...nel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, xuqiang36@...wei.com
Subject: Re: [PATCH v3] memblock,arm64: Expand the static memblock memory
 table

On Fri, May 27, 2022 at 09:18:32AM +0000, Zhou Guanghui wrote:
> In a system using HBM, a multi-bit ECC error occurs, and the BIOS
> will mark the corresponding area (for example, 2 MB) as unusable.
> When the system restarts next time, these areas are not reported
> or reported as EFI_UNUSABLE_MEMORY. Both cases lead to an increase
> in the number of memblocks, whereas EFI_UNUSABLE_MEMORY leads to a
> larger number of memblocks.
> 
> For example, if the EFI_UNUSABLE_MEMORY type is reported:
> ...
> memory[0x92]    [0x0000200834a00000-0x0000200835bfffff], 0x0000000001200000 bytes on node 7 flags: 0x0
> memory[0x93]    [0x0000200835c00000-0x0000200835dfffff], 0x0000000000200000 bytes on node 7 flags: 0x4
> memory[0x94]    [0x0000200835e00000-0x00002008367fffff], 0x0000000000a00000 bytes on node 7 flags: 0x0
> memory[0x95]    [0x0000200836800000-0x00002008369fffff], 0x0000000000200000 bytes on node 7 flags: 0x4
> memory[0x96]    [0x0000200836a00000-0x0000200837bfffff], 0x0000000001200000 bytes on node 7 flags: 0x0
> memory[0x97]    [0x0000200837c00000-0x0000200837dfffff], 0x0000000000200000 bytes on node 7 flags: 0x4
> memory[0x98]    [0x0000200837e00000-0x000020087fffffff], 0x0000000048200000 bytes on node 7 flags: 0x0
> memory[0x99]    [0x0000200880000000-0x0000200bcfffffff], 0x0000000350000000 bytes on node 6 flags: 0x0
> memory[0x9a]    [0x0000200bd0000000-0x0000200bd01fffff], 0x0000000000200000 bytes on node 6 flags: 0x4
> memory[0x9b]    [0x0000200bd0200000-0x0000200bd07fffff], 0x0000000000600000 bytes on node 6 flags: 0x0
> memory[0x9c]    [0x0000200bd0800000-0x0000200bd09fffff], 0x0000000000200000 bytes on node 6 flags: 0x4
> memory[0x9d]    [0x0000200bd0a00000-0x0000200fcfffffff], 0x00000003ff600000 bytes on node 6 flags: 0x0
> memory[0x9e]    [0x0000200fd0000000-0x0000200fd01fffff], 0x0000000000200000 bytes on node 6 flags: 0x4
> memory[0x9f]    [0x0000200fd0200000-0x0000200fffffffff], 0x000000002fe00000 bytes on node 6 flags: 0x0
> ...
> 
> The EFI memory map is parsed to construct the memblock arrays before
> the memblock arrays can be resized. As the result, memory regions
> beyond INIT_MEMBLOCK_REGIONS are lost.
> 
> Allow overriding memblock.memory array size with architecture defined
> INIT_MEMBLOCK_MEMORY_REGIONS and make arm64 to set
> INIT_MEMBLOCK_MEMORY_REGIONS to 1024 when CONFIG_EFI is enabled.
> 
> Signed-off-by: Zhou Guanghui <zhouguanghui1@...wei.com>
> Acked-by: Mike Rapoport <rppt@...ux.ibm.com>

Tested on Ampere Altra, resolving this issue as observed internally. I didn't
perform the test myself, but representing it here as a point of contact:

Tested-by: Darren Hart <darren@...amperecomputing.com>

-- 
Darren Hart
Ampere Computing / OS and Kernel