On 10.09.19 04:52, Alastair D'Silva wrote:
> From: Alastair D'Silva <alastair@xxxxxxxxxxx>
>
> The call to check_hotplug_memory_addressable() validates that the memory
> is fully addressable.
>
> Without this call, it is possible that we may remap pages that is
> not physically addressable, resulting in bogus section numbers
> being returned from __section_nr().
>
> Signed-off-by: Alastair D'Silva <alastair@xxxxxxxxxxx>
> ---
> mm/memremap.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/mm/memremap.c b/mm/memremap.c
> index 86432650f829..fd00993caa3e 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -269,6 +269,13 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
>
> mem_hotplug_begin();
>
> + error = check_hotplug_memory_addressable(res->start,
> + resource_size(res));
> + if (error) {
> + mem_hotplug_done();
> + goto err_checkrange;
> + }
> +
No need to check under the memory hotplug lock.
> /*
> * For device private memory we call add_pages() as we only need to
> * allocate and initialize struct page for the device memory. More-
> @@ -324,6 +331,7 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
>
> err_add_memory:
> kasan_remove_zero_shadow(__va(res->start), resource_size(res));
> + err_checkrange:
> err_kasan:
> untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
> err_pfn_remap:
>
--
Thanks,
David / dhildenb
