On Tue, Feb 9, 2021 at 11:32 PM Alexei Starovoitov <ast@xxxxxx> wrote: > > On 2/9/21 1:12 PM, KP Singh wrote: > > On Tue, Feb 9, 2021 at 9:57 PM Alexei Starovoitov > > <alexei.starovoitov@xxxxxxxxx> wrote: > >> > >> From: Alexei Starovoitov <ast@xxxxxxxxxx> > >> > >> Since sleepable programs are now executing under migrate_disable > >> the per-cpu maps are safe to use. > >> The map-in-map were ok to use in sleepable from the time sleepable > >> progs were introduced. > >> > >> Note that non-preallocated maps are still not safe, since there is > >> no rcu_read_lock yet in sleepable programs and dynamically allocated > >> map elements are relying on rcu protection. The sleepable programs > >> have rcu_read_lock_trace instead. That limitation will be addresses > >> in the future. > >> > >> Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> > >> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > > Acked-by: KP Singh <kpsingh@xxxxxxxxxx> > > > > Thanks! I actually tested out some of our logic which uses per-cpu maps by > > switching the programs to their sleepable counterparts > > You mean after applying this set, right? > migrate_disable is the key. > It will be difficult to backport to your kernels though. > The bpf change to enable per-cpu is easy, but backporting > sched support is a different game. > Yes after applying the whole set. Also, I think I also got it to work on 5.10 by (I am little less sure of this one though) - Backporting https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=12fa97c64dce2f3c2e6eed5dc618bb9046e40bf0 - Backporting https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/commit/?id=74d862b682f51e45d25b95b1ecf212428a4967b0 - And, backporting this set (I initially missed https://lore.kernel.org/bpf/20210209194856.24269-3-alexei.starovoitov@xxxxxxxxx where you add the calls and ran into issues). - KP
