Re: [PATCH] mm: return -ENOMEM for page-table allocation failure in insert_pages()

[David Hildenbrand (Arm)]

On 7/30/26 09:42, Lorenzo Stoakes (ARM) wrote:
> On Thu, Jul 30, 2026 at 10:13:23AM +0300, Avi Weiss wrote:
>> walk_to_pmd() returns NULL only when p4d_alloc(), pud_alloc(), or
>> pmd_alloc() fails. These are page-table allocation failures, but
>> insert_pages() currently reports them as -EFAULT.
>>
>> Return -ENOMEM instead, consistent with the subsequent pte_alloc()
>> failure and with the single-page insert_page() path, which reports
>> failure of the same page-table allocation chain as -ENOMEM.
>>
>> Address and range validation failures in vm_insert_pages() continue to
>> return -EFAULT. Keep the later -EFAULT return for
>> pte_offset_map_lock(), which is not an allocation failure.
>>
>> Fixes: 8cd3984d81d5 ("mm/memory.c: add vm_insert_pages()")
> 
> Hmm :)
> 
> This isn't really a fix. Anybody relying on this returning -ENOMEM
> vs. -EFAULT here is in a state of sin anyway (unless you can point to
> specific users who are broken).

Agreed, I am missing the problem here?

-- 
Cheers,

David