Hi, In try_to_unmap_one(), flush_cache_page() [1] is called before flush_tlb_page() [2]. The following scenario can happen: cpu0: cpu1: flush_cache_page() User writes to page ptep_clear_flush() Since the two operations on cpu0 are not atomic, a write from the user can happen right after flush_cache_page() is called, but before flushing the tlb. Thus there is a risk the last updates from the user on cpu1 won't be flushed to memory. I understand that not all CPUs need flush_cache_page, but for those that require it, how is correctness guaranteed in this case? [1] https://elixir.bootlin.com/linux/latest/source/mm/rmap.c#L1572 [2] https://elixir.bootlin.com/linux/latest/source/mm/rmap.c#L1587 Cheers Karim