Hi, On 28/06/19 15:03, Peter Zijlstra wrote: > On Fri, Jun 28, 2019 at 10:06:16AM +0200, Juri Lelli wrote: > > cpuset_rwsem is going to be acquired from sched_setscheduler() with a > > following patch. There are however paths (e.g., spawn_ksoftirqd) in > > which sched_scheduler() is eventually called while holding hotplug lock; > > this creates a dependecy between hotplug lock (to be always acquired > > first) and cpuset_rwsem (to be always acquired after hotplug lock). > > > > Fix paths which currently take the two locks in the wrong order (after > > a following patch is applied). > > Signed-off-by: Juri Lelli <juri.lelli@xxxxxxxxxx> > > This all reminds me of this: > > https://lkml.kernel.org/r/1510755615-25906-1-git-send-email-prsood@xxxxxxxxxxxxxx > > Which sadly got reverted again. If we do this now (I've always been a > proponent), then we can make that rebuild synchronous again, which > should also help here IIRC. Why was that reverted? Perf regression of some type? Thanks, Juri
