On Sun, Jul 22, 2018 at 01:21:06PM -0700, Linus Torvalds wrote: > On Sat, Jul 21, 2018 at 3:49 PM Linus Torvalds > <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > IOW, Kirill's patch now just boils down to the attached trial patch. > > Side note: we have a few rdma drivers that mess with vm_ops. > > One does so intentionally, see mlx4_ib_vma_open() in > > drivers/infiniband/hw/mlx4/main.c > > and one *may* be intentional but it's not entirely clear: > hns_roce_vma_open() may bve the same issue, but > hns_roce_disassociate_ucontext() just looks pointless in > > drivers/infiniband/hw/hns/hns_roce_main.c > > Afaik, they should just use VM_DONTCOPY to not see the fork open > case, VM_DONTEXPAND to fail a size-changing mremap, and set a > vm_ops->split() function that returns an error. > > Maybe we should have a VM_DONTSPLIT to make that ->split() case be simpler. > > Their vma->vm_ops games seem very bogus, and will cause oddities. So > right now they *will* get copied on fork and split, and then you have > random crazy pages being mapped but not the right vm_ops. In addition > to the confusion with vma_is_anonymous(). We've now got patches in rdma.git's for-next (and linux-next) that conslidates this driver code and eliminates the vm_ops games in all the infiniband drivers. Hopefully this helps whatever this vma_is_anonymous() work was. https://patchwork.kernel.org/project/linux-rdma/list/?series=19461&archive=both&state=* Regards, Jason
