On Tue, Oct 03, 2017 at 03:09:53PM -0600, Shuah Khan wrote: > On Tue, Oct 3, 2017 at 3:00 PM, Jiri Kosina <ji...@kernel.org> wrote: > > On Tue, 3 Oct 2017, Pavel Machek wrote: > > > >> > Again, I agree that the (rare) kthreads that are actually "creating" new > >> > I/O have to be somehow frozen and require special care. > >> > >> Agreed. Was any effort made to identify those special kernel threads? > > > > I don't think there is any other way than just inspecting all the > > try_to_freeze() instances in the kernel, and understanding what that > > particular kthread is doing. > > > > I've cleaned up most of the low-hanging fruit already, where the > > try_to_freeze() was obviously completely pointless, but a lot more time > > needs to be invested into this. > > > > There are about 36 drivers that call try_to_freeze() and half (18 ) of > those are media drivers. Maybe it is easier handle sub-system by > sub-system basis for a review of which one of these usages could be > removed. cc'ing Mauro and linux-media
Yes :) I guess no one reads cover letters, but indeed. To be clear, this last patch should only go in after a few kernels from now all kthreads are vetted for piece-meal wise. This patch would be the nail on the kthread freezer coffin. It should go in last, who knows how many years from now, and if ever. Luis
