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
_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@xxxxxxxxxxxxxxxxx
https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
