Re: [PATCH 1/2] mm/cma: accept memory of multi-range CMA areas

[Gupta, Pankaj]

> On systems with unaccepted memory, memblock allocations accept the
> allocated range, but when cma_declare_contiguous_multi() uses open coded
> allocation of multiple ranges, it reserves them with memblock_reserve()
> and they are never accepted.
>
> These pages are released to the buddy allocator by cma_activate_area()
> with __free_pages() that does not check for unaccepted memory, so the
> first access to such a page in a TDX or SEV-SNP guest is fatal.
>
> Accept the memory of each range when it is reserved.

Fix looks correct to me.

Any easy way to reproduce and test on SEV SNP?

Thanks,

Pankaj

> Fixes: c009da4258f9 ("mm, cma: support multiple contiguous ranges, if requested")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
> ---
>   mm/cma.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/mm/cma.c b/mm/cma.c
> index a10ea37a261da..0035efb1130a5 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -678,6 +678,8 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
>   			break;
>   		}
>   
> +		accept_memory(mlp->base, size);
> +
>   		pr_debug("created region %d: %016llx - %016llx\n",
>   		    nr, (u64)mlp->base, (u64)mlp->base + size);
>   		cmrp = &cma->ranges[nr++];