search for: arch_futex_atomic_op_inuser_inatom

On 2019/5/9 ??9:18, Michael S. Tsirkin wrote: > On Thu, May 09, 2019 at 08:58:00AM -0400, Jason Wang wrote: >> Vhost log dirty pages directly to a userspace bitmap through GUP and >> kmap_atomic() since kernel doesn't have a set_bit_to_user() >> helper. This will cause issues for the arch that has virtually tagged >> caches. The way to fix is to keep using userspace

On 2019/5/9 ??9:18, Michael S. Tsirkin wrote: > On Thu, May 09, 2019 at 08:58:00AM -0400, Jason Wang wrote: >> Vhost log dirty pages directly to a userspace bitmap through GUP and >> kmap_atomic() since kernel doesn't have a set_bit_to_user() >> helper. This will cause issues for the arch that has virtually tagged >> caches. The way to fix is to keep using userspace

...> > Good point, then I think we probably need to do manual fixup through > fixup_user_fault() if arch_futex_atomic_op_in_user() fail. This looks like a overkill, we don't need to atomic environment here actually. Instead, just keep pagefault enabled should work. So just introduce arch_futex_atomic_op_inuser_inatomic() variant with pagefault disabled there just for futex should be sufficient. Thanks