about doing this.
The idea is, first at flush_dcache_page() time, if
- page->mapping->i_mmap{,_shared} are empty lists, just mark the
- architecture private page flag bit. Later, in
- update_mmu_cache(), a check is made of this flag bit, and if
- set the flush is done and the flag bit is cleared.
+ page->mapping->i_mmap is an empty tree and ->i_mmap_nonlinear
+ an empty list, just mark the architecture private page flag bit.
+ Later, in update_mmu_cache(), a check is made of this flag bit,
+ and if set the flush is done and the flag bit is cleared.
IMPORTANT NOTE: It is often important, if you defer the flush,
that the actual flush occurs on the same CPU