Messages in this thread | | | Date | Thu, 8 Jul 2021 16:17:10 +0200 | From | Heiko Carstens <> | Subject | Re: [PATCH] s390: preempt: Fix preempt_count initialization |
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On Wed, Jul 07, 2021 at 05:33:38PM +0100, Valentin Schneider wrote: > S390's init_idle_preempt_count(p, cpu) doesn't actually let us initialize the > preempt_count of the requested CPU's idle task: it unconditionally writes > to the current CPU's. This clearly conflicts with idle_threads_init(), > which intends to initialize *all* the idle tasks, including their > preempt_count (or their CPU's, if the arch uses a per-CPU preempt_count). > > Unfortunately, it seems the way s390 does things doesn't let us initialize > every possible CPU's preempt_count early on, as the pages where this > resides are only allocated when a CPU is brought up and are freed when it > is brought down. > > Let the arch-specific code set a CPU's preempt_count when its lowcore is > allocated, and turn init_idle_preempt_count() into an empty stub. > > Fixes: f1a0a376ca0c ("sched/core: Initialize the idle task with preemption disabled") > Reported-by: Guenter Roeck <linux@roeck-us.net> > Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> > --- > arch/s390/include/asm/preempt.h | 16 ++++------------ > arch/s390/kernel/setup.c | 1 + > arch/s390/kernel/smp.c | 1 + > 3 files changed, 6 insertions(+), 12 deletions(-)
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Vasily, can you pick this one up, please?
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