On Wed, Jun 26, 2019 at 09:59:58AM +0800, Linus Torvalds wrote: > On Tue, Jun 25, 2019 at 1:31 PM Peter Xu <peterx@xxxxxxxxxx> wrote: > > > > Yes that sounds reasonable to me, and that matches perfectly with > > TASK_INTERRUPTIBLE and TASK_KILLABLE. The only thing that I am a bit > > uncertain is whether we should define FAULT_FLAG_INTERRUPTIBLE as a > > new bit or make it simply a combination of: > > > > FAULT_FLAG_KILLABLE | FAULT_FLAG_USER > > It needs to be a new bit, I think. > > Some things could potentially care about the difference between "can I > abort this thing because the task will *die* and never see the end > result" and "can I abort this thing because it will be retried". > > For a regular page fault, maybe FAULT_FLAG_INTERRUPTBLE will always be > set for the same things that set FAULT_FLAG_KILLABLE when it happens > from user mode, but at least conceptually I think they are different, > and it could make a difference for things like get_user_pages() or > similar. > > Also, I actually don't think we should ever expose FAULT_FLAG_USER to > any fault handlers anyway. It has a very specific meaning for memory > cgroup handling, and no other fault handler should likely ever care > about "was this a user fault". So I'd actually prefer for people to > ignore and forget that hacky flag entirely, rather than give it subtle > semantic meaning together with KILLABLE. OK. > > [ Side note: this is the point where I may soon lose internet access, > so I'll probably not be able to participate in the discussion any more > for a while ] Appreciate for these suggestions. I'll prepare something with that new bit and see whether that could be accepted. I'll also try to split those out of the bigger series. Thanks, -- Peter Xu
