Re: [PATCH v4 19/25] proc/task_mmu: Ignore ZONE_DEVICE pages

[David Hildenbrand <david@redhat.com>]

On 17.12.24 06:13, Alistair Popple wrote:
> The procfs mmu files such as smaps currently ignore device dax and fs
> dax pages because these pages are considered special. To maintain
> existing behaviour once these pages are treated as normal pages and
> returned from vm_normal_page() add tests to explicitly skip them.
> 
> Signed-off-by: Alistair Popple <apopple@nvidia.com>
> ---
>   fs/proc/task_mmu.c | 18 ++++++++++++++----
>   1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 38a5a3e..c9b227a 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -801,6 +801,8 @@ static void smaps_pte_entry(pte_t *pte, unsigned long addr,
>   
>   	if (pte_present(ptent)) {
>   		page = vm_normal_page(vma, addr, ptent);
> +		if (page && (is_device_dax_page(page) || is_fsdax_page(page)))

This "is_device_dax_page(page) || is_fsdax_page(page)" is a common theme 
here, likely we should have a special helper?


But, don't we actually want to include them in the smaps output now? I 
think we want.

The rmap code will indicate these pages in /proc/meminfo, per-node info, 
in the memcg ... as "Mapped:" etc.

So likely we just want to also indicate them here, or is there any 
downsides we know of?

-- 
Cheers,

David / dhildenb