Re: Re: [PATCH] pstore: ramoops: support pmsg size larger than kmalloc limitation

[Yuxiao Zhang]

Thanks for reviewing the patch.

On 28 Jun 2023 07:30:16 +0200, Greg KH wrote:
>What is that max size?

The max size is arch dependent, it should be 2^(PAGE_SIZE+MAX_ORDER). In our environment it is 4M.

>what in-kernel user is hitting this in the pstore implementation?

We are trying to use pmsg to hold a core dump file, so we have pmsg-size=32M and thus hit this issue.

Other than us, here is one I found that trying to save dmesg beyond kmalloc limitaton:
https://lore.kernel.org/lkml/b2d66d9f-15a6-415c-2485-44649027a1d5@xxxxxxxxxx/T/

Thanks,
-Yuxiao Zhang