There's no need to spell out all the special cases, also doing it this way
makes it absolutely clear that we preclude unmergeable VMAs in general, and
puts the other excluded flags in stark and clear contrast.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 mm/ksm.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/ksm.c b/mm/ksm.c
index 08d486f188ff..d0c763abd499 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -679,9 +679,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_v
 
 static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags)
 {
-	if (vm_flags & (VM_SHARED   | VM_MAYSHARE   | VM_PFNMAP  |
-			VM_IO       | VM_DONTEXPAND | VM_HUGETLB |
-			VM_MIXEDMAP | VM_DROPPABLE))
+	if (vm_flags & (VM_SHARED  | VM_MAYSHARE | VM_SPECIAL |
+			VM_HUGETLB | VM_DROPPABLE))
 		return false;		/* just ignore the advice */
 
 	if (file_is_dax(file))
-- 
2.49.0

On 2025/5/19 16:51, Lorenzo Stoakes wrote:
> There's no need to spell out all the special cases, also doing it this way
> makes it absolutely clear that we preclude unmergeable VMAs in general, and
> puts the other excluded flags in stark and clear contrast.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Nice.

Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>

Thanks!

> ---
>   mm/ksm.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 08d486f188ff..d0c763abd499 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -679,9 +679,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_v
>   
>   static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags)
>   {
> -	if (vm_flags & (VM_SHARED   | VM_MAYSHARE   | VM_PFNMAP  |
> -			VM_IO       | VM_DONTEXPAND | VM_HUGETLB |
> -			VM_MIXEDMAP | VM_DROPPABLE))
> +	if (vm_flags & (VM_SHARED  | VM_MAYSHARE | VM_SPECIAL |
> +			VM_HUGETLB | VM_DROPPABLE))
>   		return false;		/* just ignore the advice */
>   
>   	if (file_is_dax(file))

On 19.05.25 10:51, Lorenzo Stoakes wrote:
> There's no need to spell out all the special cases, also doing it this way
> makes it absolutely clear that we preclude unmergeable VMAs in general, and
> puts the other excluded flags in stark and clear contrast.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> ---
>   mm/ksm.c | 5 ++---
>   1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 08d486f188ff..d0c763abd499 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -679,9 +679,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr, bool lock_v
>   
>   static bool ksm_compatible(const struct file *file, vm_flags_t vm_flags)
>   {
> -	if (vm_flags & (VM_SHARED   | VM_MAYSHARE   | VM_PFNMAP  |
> -			VM_IO       | VM_DONTEXPAND | VM_HUGETLB |
> -			VM_MIXEDMAP | VM_DROPPABLE))
> +	if (vm_flags & (VM_SHARED  | VM_MAYSHARE | VM_SPECIAL |
> +			VM_HUGETLB | VM_DROPPABLE))
>   		return false;		/* just ignore the advice */

Stumbled over that recently myself ... (grepping for VM_SPECIAL does not 
return many results)

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

-- 
Cheers,

David / dhildenb