On Wed, 28 Mar 2018, Laurent Dufour wrote: > >> This configuration variable will be used to build the code needed to > >> handle speculative page fault. > >> > >> By default it is turned off, and activated depending on architecture > >> support. > >> > >> Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > >> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxxxxxxx> > >> --- > >> mm/Kconfig | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/mm/Kconfig b/mm/Kconfig > >> index abefa573bcd8..07c566c88faf 100644 > >> --- a/mm/Kconfig > >> +++ b/mm/Kconfig > >> @@ -759,3 +759,6 @@ config GUP_BENCHMARK > >> performance of get_user_pages_fast(). > >> > >> See tools/testing/selftests/vm/gup_benchmark.c > >> + > >> +config SPECULATIVE_PAGE_FAULT > >> + bool > > > > Should this be configurable even if the arch supports it? > > Actually, this is not configurable unless by manually editing the .config file. > > I made it this way on the Thomas's request : > https://lkml.org/lkml/2018/1/15/969 > > That sounds to be the smarter way to achieve that, isn't it ? > Putting this in mm/Kconfig is definitely the right way to go about it instead of any generic option in arch/*. My question, though, was making this configurable by the user: config SPECULATIVE_PAGE_FAULT bool "Speculative page faults" depends on X86_64 || PPC default y help .. It's a question about whether we want this always enabled on x86_64 and power or whether the user should be able to disable it (right now they can't). With a large feature like this, you may want to offer something simple (disable CONFIG_SPECULATIVE_PAGE_FAULT) if someone runs into regressions.
