On Fri, May 03, 2019 at 10:47:37AM -0700, tip-bot for Nicholas Piggin wrote: > Commit-ID: 9219565aa89033a9cfdae788c1940473a1253d6c > Gitweb: > https://git.kernel.org/tip/9219565aa89033a9cfdae788c1940473a1253d6c > Author: Nicholas Piggin <[email protected]> > AuthorDate: Thu, 11 Apr 2019 13:34:47 +1000 > Committer: Ingo Molnar <[email protected]> > CommitDate: Fri, 3 May 2019 19:42:58 +0200 > > sched/isolation: Require a present CPU in housekeeping mask > > During housekeeping mask setup, currently a possible CPU is required. > That does not guarantee the CPU would be available at boot time, so > check to ensure that at least one present CPU is in the mask. > > Signed-off-by: Nicholas Piggin <[email protected]> > Signed-off-by: Peter Zijlstra (Intel) <[email protected]> > Cc: Frederic Weisbecker <[email protected]> > Cc: Linus Torvalds <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Rafael J . Wysocki <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: [email protected] > Link: https://lkml.kernel.org/r/[email protected] > Signed-off-by: Ingo Molnar <[email protected]> > --- > kernel/sched/isolation.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c > index b02d148e7672..687302051a27 100644 > --- a/kernel/sched/isolation.c > +++ b/kernel/sched/isolation.c > @@ -65,6 +65,7 @@ void __init housekeeping_init(void) > static int __init housekeeping_setup(char *str, enum hk_flags flags) > { > cpumask_var_t non_housekeeping_mask; > + cpumask_var_t tmp; > int err; > > alloc_bootmem_cpumask_var(&non_housekeeping_mask); > @@ -75,16 +76,23 @@ static int __init housekeeping_setup(char *str, enum > hk_flags flags) > return 0; > } > > + alloc_bootmem_cpumask_var(&tmp); > if (!housekeeping_flags) { > alloc_bootmem_cpumask_var(&housekeeping_mask); > cpumask_andnot(housekeeping_mask, > cpu_possible_mask, non_housekeeping_mask); > - if (cpumask_empty(housekeeping_mask)) > + > + cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask); > + if (cpumask_empty(tmp)) { > + pr_warn("Housekeeping: must include one present CPU, " > + "using boot CPU:%d\n", smp_processor_id()); > __cpumask_set_cpu(smp_processor_id(), > housekeeping_mask); > + __cpumask_clear_cpu(smp_processor_id(), > non_housekeeping_mask);
Ah that line (along with its twin below) is actually also a fix for the upstream code. If the housekeeping mask is empty and we force the current one, we must make sure that the current CPU is excluded from the nohz_full set. Ideally it should have come as a separate patch but it's nice that you fixed it anyway. Thanks! Acked-by: Frederic Weisbecker <[email protected]> > + } > } else { > - cpumask_var_t tmp; > - > - alloc_bootmem_cpumask_var(&tmp); > + cpumask_andnot(tmp, cpu_present_mask, non_housekeeping_mask); > + if (cpumask_empty(tmp)) > + __cpumask_clear_cpu(smp_processor_id(), > non_housekeeping_mask); > cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask); > if (!cpumask_equal(tmp, housekeeping_mask)) { > pr_warn("Housekeeping: nohz_full= must match > isolcpus=\n"); > @@ -92,8 +100,8 @@ static int __init housekeeping_setup(char *str, enum > hk_flags flags) > free_bootmem_cpumask_var(non_housekeeping_mask); > return 0; > } > - free_bootmem_cpumask_var(tmp); > } > + free_bootmem_cpumask_var(tmp); > > if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_TICK)) { > if (IS_ENABLED(CONFIG_NO_HZ_FULL)) {
