This is a note to let you know that I've just added the patch titled s390/topology: make "topology=off" parameter work to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-topology-make-topology-off-parameter-work.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Thu Nov 9 09:48:01 CET 2017 From: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Date: Thu, 29 Dec 2016 13:52:52 +0100 Subject: s390/topology: make "topology=off" parameter work From: Heiko Carstens <heiko.carstens@xxxxxxxxxx> [ Upstream commit 68cc795d1933285705ced6d841ef66c00ce98cbe ] The "topology=off" kernel parameter is supposed to prevent the kernel to use hardware topology information to generate scheduling domains etc. For an unknown reason I implemented this in a very odd way back then: instead of simply clearing the MACHINE_HAS_TOPOLOGY flag within the lowcore I added a second variable which indicated that topology information should not be used. This is more than suboptimal since it partially doesn't work. For the fake NUMA case topology information is still considered and scheduling domains will be created based on this. To fix this and to simplify the code get rid of the extra variable and implement the "topology=off" case like it is done for other features. Signed-off-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/kernel/early.c | 12 ++++++++++++ arch/s390/kernel/topology.c | 11 ++--------- 2 files changed, 14 insertions(+), 9 deletions(-) --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -363,6 +363,18 @@ static inline void save_vector_registers #endif } +static int __init topology_setup(char *str) +{ + bool enabled; + int rc; + + rc = kstrtobool(str, &enabled); + if (!rc && !enabled) + S390_lowcore.machine_flags &= ~MACHINE_HAS_TOPOLOGY; + return rc; +} +early_param("topology", topology_setup); + static int __init disable_vector_extension(char *str) { S390_lowcore.machine_flags &= ~MACHINE_FLAG_VX; --- a/arch/s390/kernel/topology.c +++ b/arch/s390/kernel/topology.c @@ -37,7 +37,6 @@ static void set_topology_timer(void); static void topology_work_fn(struct work_struct *work); static struct sysinfo_15_1_x *tl_info; -static bool topology_enabled = true; static DECLARE_WORK(topology_work, topology_work_fn); /* @@ -56,7 +55,7 @@ static cpumask_t cpu_group_map(struct ma cpumask_t mask; cpumask_copy(&mask, cpumask_of(cpu)); - if (!topology_enabled || !MACHINE_HAS_TOPOLOGY) + if (!MACHINE_HAS_TOPOLOGY) return mask; for (; info; info = info->next) { if (cpumask_test_cpu(cpu, &info->mask)) @@ -71,7 +70,7 @@ static cpumask_t cpu_thread_map(unsigned int i; cpumask_copy(&mask, cpumask_of(cpu)); - if (!topology_enabled || !MACHINE_HAS_TOPOLOGY) + if (!MACHINE_HAS_TOPOLOGY) return mask; cpu -= cpu % (smp_cpu_mtid + 1); for (i = 0; i <= smp_cpu_mtid; i++) @@ -413,12 +412,6 @@ static const struct cpumask *cpu_drawer_ return &per_cpu(cpu_topology, cpu).drawer_mask; } -static int __init early_parse_topology(char *p) -{ - return kstrtobool(p, &topology_enabled); -} -early_param("topology", early_parse_topology); - static struct sched_domain_topology_level s390_topology[] = { { cpu_thread_mask, cpu_smt_flags, SD_INIT_NAME(SMT) }, { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, Patches currently in stable-queue which might be from heiko.carstens@xxxxxxxxxx are queue-4.9/s390-topology-make-topology-off-parameter-work.patch queue-4.9/sched-cputime-powerpc32-fix-stale-scaled-stime-on-context-switch.patch