Re: [PATCH v5] mm: mmap: map MAP_STACK to VM_NOHUGEPAGE only if THP is enabled

[David Hildenbrand <david@redhat.com>]

On 07.05.25 15:28, Ignacio Moreno Gonzalez via B4 Relay wrote:
> From: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>
> 
> commit c4608d1bf7c6 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE") maps
> the mmap option MAP_STACK to VM_NOHUGEPAGE. This is also done if
> CONFIG_TRANSPARENT_HUGEPAGE is not defined. But in that case, the
> VM_NOHUGEPAGE does not make sense.
> 
> I discovered this issue when trying to use the tool CRIU to checkpoint
> and restore a container. Our running kernel is compiled without
> CONFIG_TRANSPARENT_HUGEPAGE. CRIU parses the output of
> /proc/<pid>/smaps and saves the "nh" flag. When trying to restore the
> container, CRIU fails to restore the "nh" mappings, since madvise()
> MADV_NOHUGEPAGE always returns an error because
> CONFIG_TRANSPARENT_HUGEPAGE is not defined.
> 
> Fixes: c4608d1bf7c6 ("mm: mmap: map MAP_STACK to VM_NOHUGEPAGE")
> Cc: stable@vger.kernel.org
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
> Signed-off-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com>

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb