On Tue, Mar 27, 2018 at 08:29:39AM +0200, Michal Hocko wrote: > On Tue 27-03-18 02:20:39, Yang Shi wrote: > [...] > The patch looks reasonable to me. Maybe it would be better to be more > explicit about the purpose of the patch. As others noticed, this alone > wouldn't solve the mmap_sem contention issues. I _think_ that if you > were more explicit about the mmap_sem abuse it would trigger less > questions. > >From what I gather even with other fixes the kernel will still end up grabbing the semaphore. In this case I don't see what's the upside of adding the spinlock for args. The downside is growth of mm_struct. i.e. the code can be refactored to just hold the lock and relock only if necessary (unable to copy to user without faulting) -- Mateusz Guzik
