Re: [PATCH v2 3/3] mm/vma: remove mmap() retry merge

[Vlastimil Babka <vbabka@suse.cz>]

On 5/9/25 14:13, Lorenzo Stoakes wrote:
> We have now introduced a mechanism that obviates the need for a reattempted
> merge via the mmap_prepare() file hook, so eliminate this functionality
> altogether.
> 
> The retry merge logic has been the cause of a great deal of complexity in
> the past and required a great deal of careful manoeuvring of code to ensure
> its continued and correct functionality.
> 
> It has also recently been involved in an issue surrounding maple tree
> state, which again points to its problematic nature.
> 
> We make it much easier to reason about mmap() logic by eliminating this and
> simply writing a VMA once. This also opens the doors to future optimisation
> and improvement in the mmap() logic.
> 
> For any device or file system which encounters unwanted VMA fragmentation
> as a result of this change (that is, having not implemented .mmap_prepare
> hooks), the issue is easily resolvable by doing so.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Reviewed-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>