Re: [PATCH] mm/rmap: remove unnecessary page_table_lock

David Hildenbrand
2024-04-22T11:24:45Z

On 22.04.24 12:52, Yajun Deng wrote:
> page_table_lock is a lock that for page table, we won't change page
> table in __anon_vma_prepare(). As we can see, it works well in
> anon_vma_clone(). They do the same operation.

We are reusing mm->page_table_lock to serialize, not the *actual*
low-level page table locks that really protect PTEs.

With that locking gone, there would be nothing protection vma->anon_vma.

Note that anon_vma_clone() is likely called with the mmap_lock held in
write mode, which is not the case for __anon_vma_prepare() ...

I think this change is wrong.

--
Cheers,

David / dhildenb