On Tue 07-02-17 23:25:17, Thomas Gleixner wrote: > On Tue, 7 Feb 2017, Christoph Lameter wrote: > > On Tue, 7 Feb 2017, Michal Hocko wrote: > > > > > I am always nervous when seeing hotplug locks being used in low level > > > code. It has bitten us several times already and those deadlocks are > > > quite hard to spot when reviewing the code and very rare to hit so they > > > tend to live for a long time. > > > > Yep. Hotplug events are pretty significant. Using stop_machine_XXXX() etc > > would be advisable and that would avoid the taking of locks and get rid of > > all the > > ocmplexity, reduce the code size and make the overall system much more > > reliable. > > Huch? stop_machine() is horrible and heavy weight. Don't go there, there > must be simpler solutions than that.
Absolutely agreed. We are in the page allocator path so using the stop_machine* is just ridiculous. And, in fact, there is a much simpler solution [1] [1] http://lkml.kernel.org/r/20170207201950.20482-1-mho...@kernel.org -- Michal Hocko SUSE Labs
