search for: have_futex_cmpxchg

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 virtual address. Fortunately, futex has a cmpxchg to userspace memory helper futex_atomic_cmpxchg_inatomic(). So switch to use it to exchange the

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 virtual address. Fortunately, futex has a cmpxchg to userspace memory helper futex_atomic_cmpxchg_inatomic(). So switch to use it to exchange the

On Mon, May 06, 2019 at 10:23:29PM -0400, Jason Wang wrote: > Note: there're archs (few non popular ones) that don't implement > futex helper, we can't log dirty pages. We can fix them on top or > simply disable LOG_ALL features of vhost. That means vhost now has to depend on HAVE_FUTEX_CMPXCHG to make sure we have a working implementation. > #include <linux/sched/signal.h> > #include <linux/interval_tree_generic.h> > #include <linux/nospec.h> > +#include <asm/futex.h> Also please include the futex maintainers to make sure they are fine with this...